ONEOK INC /NEW/
S-3, 1999-07-13
NATURAL GAS TRANSMISISON & DISTRIBUTION
Previous: PIONEER NATURAL RESOURCES CO, 8-K, 1999-07-13
Next: ONEOK INC /NEW/, 8-K, 1999-07-13



<PAGE>

     As filed with the Securities and Exchange Commission on July 13, 1999

                                                      Registration No. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                --------------
                                    FORM S-3
                             REGISTRATION STATEMENT
                                     Under
                           the Securities Act of 1933
                                --------------
       ONEOK, Inc.                 Oklahoma                  73-1520922
  ONEOK Capital Trust I            Delaware              To be applied for
  ONEOK Capital Trust II           Delaware              To be applied for
   (Exact Name of Each         (State or Other             (IRS Employer
 Registrant as Specified       Jurisdiction of          Identification No.)
     in Its Charter)           Incorporation or
                                Organization)
       ONEOK, Inc.          ONEOK Capital Trust I      ONEOK Capital Trust II
  100 West Fifth Street     100 West Fifth Street      100 West Fifth Street
  Tulsa, Oklahoma 74103     Tulsa, Oklahoma 74103      Tulsa, Oklahoma 74103
      (918) 588-7000            (918) 588-7000             (918) 588-7000
 (Address, Including Zip   (Address, Including Zip    (Address, Including Zip
   Code, and Telephone       Code, and Telephone        Code, and Telephone
  Number, Including Area    Number, Including Area     Number, Including Area
      Code, of Each             Code, of Each              Code, of Each
  Registrant's Principal    Registrant's Principal     Registrant's Principal
    Executive Offices)        Executive Offices)         Executive Offices)
                                James C. Kneale
             Vice President, Treasurer and Chief Financial Officer
                                  ONEOK, Inc.
                             100 West Fifth Street
                             Tulsa, Oklahoma 74103
                                 (918) 588-7000
 (Name, Address, Including Zip Code, and Telephone Number, Including Area Code,
                    of Agent For Service of Each Registrant)
                                   Copies to:
           Donald A. Kihle                        Robert A. Yolles
            Gable & Gowals                   Jones, Day, Reavis & Pogue
        100 West Fifth Street                      77 West Wacker
        Tulsa, Oklahoma 74103                  Chicago, Illinois 60601
            (918) 585-8141                         (312) 782-3939
   Approximate date of commencement of proposed sale to the public: From time
to time after the effective date of this registration statement.
                                --------------
   If the only securities being registered on this form are to be offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [_]
   If any of the securities being registered on this form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or
interest reinvestment plans, check the following box: [X]
   If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. [_]
   If this form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]
   If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [_]
                        CALCULATION OF REGISTRATION FEE
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<TABLE>
<CAPTION>
             Title of each                 Proposed Maximum
          Class of Securities             Aggregate Offering       Amount of
            to be Registered                 Price (1)(2)      Registration Fee
- -------------------------------------------------------------------------------
<S>                                       <C>                 <C>
Preferred Trust Securities of ONEOK
 Capital Trust I and ONEOK Capital Trust
 II ("Preferred Securities") (3).......
Junior Subordinated Debentures of ONEOK,
 Inc. ("Junior Subordinated Debentures")
 (3)...................................      $300,000,000           $83,400
Guarantees of Preferred Trust Securities
 of ONEOK Capital Trust I and ONEOK
 Capital Trust II by ONEOK, Inc. (each,
 a "Preferred Securities Guarantee")
 (4)...................................
- -------------------------------------------------------------------------------
</TABLE>
- --------------------------------------------------------------------------------
                                         (footnotes continued on following page)
<PAGE>

 (continued from previous page)

(1) Such indeterminate amount of Preferred Securities and Junior Subordinated
    Debentures as may from time to time be issued at indeterminate prices.
    Junior Subordinated Debentures may be issued and sold to ONEOK Capital
    Trust I or ONEOK Capital Trust II, in which event such Junior Subordinated
    Debentures may later be distributed to the holders of Preferred Securities
    upon a dissolution of ONEOK Capital Trust I or ONEOK Capital Trust II and
    the distribution of the assets thereof.
(2) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(o) and exclusive of accrued interest and dividends, if
    any. Calculated using the maximum aggregate offering price of such
    indeterminate amount of Preferred Securities and Junior Subordinated
    Debentures that may be offered from time to time at an offering price below
    their face value.
(3) In no event will the aggregate initial public offering price of the
    securities issued under this Registration Statement exceed $300,000,000,
    exclusive of accrued distributions and interest, if any. Junior
    Subordinated Debentures may be issued and sold by ONEOK to ONEOK Capital
    Trust I or ONEOK Capital Trust II in an aggregate principal amount equal to
    the aggregate stated liquidation preference of any Preferred Securities and
    Common Securities to be issued and sold by ONEOK Capital Trust I or ONEOK
    Capital Trust II. Junior Subordinated Debentures may later be distributed
    for no additional consideration to the holders of the Preferred Securities
    upon a dissolution of ONEOK Capital Trust I or ONEOK Capital Trust II and
    the distribution of the assets thereof.
(4) Includes the rights of holders of the Preferred Securities of ONEOK Capital
    Trust I or ONEOK Capital Trust II under the applicable Preferred Securities
    Guarantee and back-up undertakings, consisting of obligations by ONEOK,
    Inc. to provide certain indemnities in respect of, and pay and be
    responsible for certain expenses, costs, liabilities and debts of, as
    applicable, ONEOK Capital Trust I or ONEOK Capital Trust II and such other
    obligations of ONEOK as are set forth in the Amended and Restated Trust
    Agreement, the Junior Subordinated Indenture, Supplemental Indentures
    thereto and the Agreements as to Expenses and Liabilities, in each case as
    further described in the Registration Statement. No separate consideration
    will be received for any Preferred Securities Guarantee or any back-up
    undertaking.

   The Registrants hereby amend this Registration Statement on such date or
dates as may be necessary to delay its effective date until the Registrants
shall file a further amendment which specifically states that this Registration
Statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until this Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a),
may determine.
                                --------------
                                --------------
                                EXPLANATORY NOTE

   This Registration Statement includes a prospectus supplement that relates to
the proposed offering of Preferred Securities as described therein currently
planned to commence as soon as practicable after the effective date of the
Registration Statement.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+The information in this preliminary prospectus supplement is not complete and +
+may be changed. We may not sell these securities until the registration       +
+statement filed with the Securities and Exchange Commission is effective.     +
+This preliminary prospectus supplement is not an offer to sell these          +
+securities and it is not soliciting an offer to buy these securities in any   +
+state where the offer or sale is not permitted.                               +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                    SUBJECT TO COMPLETION, DATED JULY 13, 1999

Prospectus Supplement
(To Prospectus Dated      , 1999)

                              Preferred Securities

                             ONEOK Capital Trust I

                            % Preferred Trust Securities
                (Liquidation Amount $25 per Preferred Security)
                    Fully and Unconditionally Guaranteed by
                                  ONEOK, Inc.

                                  -----------

  ONEOK Capital Trust I is offering its preferred securities that represent
preferred ownership interests in the assets of ONEOK Capital Trust I. Holders
of the preferred securities will be entitled to receive cash distributions at
an annual rate of     %. The sole asset of ONEOK Capital Trust I will be junior
subordinated debentures of ONEOK, Inc. that have the same payment terms as the
preferred securities.

  We urge you to carefully read the "Risk Factors" section beginning on page S-
9, where we describe specific risks associated with the preferred securities,
along with this prospectus supplement and the accompanying prospectus, before
you make your investment decision.

  We plan to list the preferred securities on the New York Stock Exchange under
the trading symbol        . We expect that the preferred securities will begin
trading on the New York Stock Exchange within 30 days after they are first
issued.

  Purchasers will be required to pay accrued distributions on the preferred
securities from           , 1999, if settlement occurs after that date.
Underwriting commissions of $     per preferred security will be paid by ONEOK,
Inc.

<TABLE>
<CAPTION>
                                                     Per Preferred
                                                       Security     Total
   <S>                                               <C>           <C>
   Public Offering Price............................    $25.00     $
   Proceeds to ONEOK Capital Trust I................    $25.00     $
</TABLE>

  Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
adequacy or accuracy of this prospectus supplement or the accompanying
prospectus. Any representation to the contrary is a criminal offense.

                                  -----------

                            PaineWebber Incorporated

                                  -----------

           The date of this prospectus supplement is           , 1999.
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                       Page
                                       ----
         Prospectus Supplement
<S>                                    <C>

Forward-Looking Statements...........   S-2
Summary Information..................   S-4
Risk Factors.........................   S-9
ONEOK................................  S-13
ONEOK Capital Trust I................  S-13
Accounting Treatment of ONEOK Capital
 Trust I.............................  S-14
Selected Consolidated Financial
 Information of ONEOK................  S-14
Use of Proceeds......................  S-15
Description of the Preferred
 Securities..........................  S-16
Description of the Junior
 Subordinated Debentures.............  S-26
Relationship among the Preferred
 Securities, the Junior Subordinated
 Debentures and the Preferred
 Securities Guarantee................  S-28
Taxation.............................  S-30
Underwriting.........................  S-34
Legal Matters........................  S-35
Experts..............................  S-36
</TABLE>
<TABLE>
<CAPTION>
                                                  Page
                                                  ----
                  Prospectus
<S>                                                <C>
Where You Can Find More Information..............    2
Documents Incorporated by Reference..............    2
ONEOK............................................    3
The ONEOK Trusts.................................    3
Use of Proceeds..................................    4
Ratio of Earnings to Fixed Charges...............    4
Accounting Treatment of the ONEOK Trusts.........    5
Description of the Preferred Securities..........    5
Description of the Junior Subordinated
 Debentures......................................    6
Description of the Preferred Securities
 Guarantees......................................   12
Relationship among the Preferred Securities, the
Junior Subordinated Debentures and the Preferred
 Securities Guarantees...........................   15
ERISA Matters....................................   16
Plan of Distribution.............................   17
Legal Matters....................................   18
Experts..........................................   18
</TABLE>

                               ----------------

   You should rely only on the information contained or incorporated by
reference in this prospectus supplement, the accompanying prospectus or any
pricing supplement. We have not authorized anyone to provide you with any other
information. We are not making an offer of these securities in any jurisdiction
where the offer is not permitted. The information in this prospectus
supplement, the accompanying prospectus or any document incorporated by
reference is accurate only as of the date on the front of the document
containing the information.

   The following information concerning ONEOK, Inc., ONEOK Capital Trust I, the
preferred securities, the junior subordinated debentures and the preferred
securities guarantee supplements, and should be read in conjunction with, the
information contained in the accompanying prospectus. Capitalized terms used in
this prospectus supplement have the same meanings as in the accompanying
prospectus.

                               ----------------

                           FORWARD-LOOKING STATEMENTS

   Some of the statements in this prospectus supplement and the prospectus
concerning ONEOK's expectations or predictions of the future are "forward-
looking statements" within the meaning of the Private Securities Litigation
Reform Act of 1995. These statements are intended to be covered by the safe
harbor provision of the Securities Act of 1933 and the Securities Exchange Act
of 1934. Forward-looking statements are based on management's beliefs and
assumptions based on information currently available. It is important to note
that actual results could differ materially from those projected in such
forward-looking statements. Factors that may impact forward-looking statements
include, but are not limited to, the following:

  .  the effects of weather and other natural phenomena;

  .  increased competition from other energy suppliers as well as alternative
     forms of energy;

                                      S-2
<PAGE>

  .  the capital intensive nature of ONEOK's business;

  .  economic climate and growth in the geographic areas in which ONEOK does
     business;

  .  the uncertainty of gas and oil reserve estimates;

  .  the timing and extent of changes in commodity prices for natural gas,
     natural gas liquids, electricity, and crude oil;

  .  the nature and projected profitability of potential projects and other
     investments available to ONEOK

  .  conditions of capital markets and equity markets;

  .  Year 2000 issues;

  .  the effects of changes in governmental policies and regulatory actions,
     including income taxes, environmental compliance, authorized rates, and
     deregulation or "unbundling" of natural gas business; and

  .  the pending merger with Southwest Gas Corporation, and any regulatory
     delay or conditions imposed by regulatory bodies in connection with the
     Southwest Gas merger.

   Accordingly, while ONEOK believes these forward-looking statements to be
reasonable, there can be no assurance that they will approximate actual
experience or that the expectations derived from them will be realized. When
used in ONEOK documents, the words "anticipate," "expect," "projection," "goal"
or similar words are intended to identify forward-looking statements. ONEOK
does not have any intention or obligation to update forward-looking statements
after any distribution of this prospectus supplement and the accompanying
prospectus even if new information, future events or other circumstances have
made them incorrect or misleading.

                                      S-3
<PAGE>

                              SUMMARY INFORMATION

   The following information supplements, and should be read together with, the
information contained in other parts of this prospectus supplement and in the
accompanying prospectus. This summary highlights selected information from this
prospectus supplement and the accompanying prospectus to help you understand
the preferred securities. You should carefully read this prospectus supplement
and the accompanying prospectus to understand fully the terms of the preferred
securities as well as the tax and other considerations that are important to
you in making a decision about whether to invest in the preferred securities.
You should pay special attention to the "Risk Factors" section beginning on
Page S-9 of this prospectus supplement to determine whether an investment in
the preferred securities is appropriate for you.

ONEOK

   ONEOK, Inc. is an Oklahoma corporation. ONEOK and its subsidiaries engage in
several aspects of the energy business. ONEOK purchases, gathers, compresses,
transports and stores natural gas for distribution to consumers. ONEOK
transports gas for others and leases pipeline capacity to others for their use
in transporting gas. ONEOK drills for and produces gas and oil, extracts and
sells natural gas liquids and engages in the gas marketing business. In
addition, ONEOK leases and operates a headquarters office building (leasing
space it does not use to others) and owns and operates a related parking
facility. As a regulated natural gas utility, ONEOK distributes natural gas to
approximately 1.4 million customers in the states of Oklahoma and Kansas.

   ONEOK has agreed to acquire Southwest Gas by merger for cash of
approximately $917 million. Southwest Gas is a regulated natural gas utility
that distributes natural gas to      customers in the states of Nevada, Arizona
and California.

   The principal executive offices of ONEOK are located at 100 West Fifth
Street, Tulsa, Oklahoma 74103, and its telephone number is (918) 588-7000.

ONEOK Capital Trust I

   ONEOK Capital Trust I is a Delaware business trust. Its principal office and
place of business are located at 100 West Fifth Street, Tulsa, Oklahoma 74103,
and its telephone number is (918) 588-7000.

   ONEOK Capital Trust I will sell its preferred securities to the public and
its common securities to ONEOK. Together, the preferred securities and the
common securities are referred to as the trust securities. ONEOK Capital Trust
I will use the proceeds from these sales to purchase ONEOK's     % Junior
Subordinated Debentures due           ,     . The junior subordinated
debentures will have the same financial terms as the preferred securities.
ONEOK will guarantee payments made on the preferred securities as described in
this prospectus supplement.

   Under the trust agreement establishing ONEOK Capital Trust I,
                will act as property trustee, a direct or indirect wholly owned
subsidiary of ONEOK will act as administrative trustee and             will be
the Delaware trustee of ONEOK Capital Trust I.            will act as indenture
trustee under the indenture pursuant to which the junior subordinated
debentures will be issued and will act as guarantee trustee under the preferred
securities guarantee of ONEOK. The property trustee, administrative trustee and
Delaware trustee are sometimes referred to as the securities trustees.

                                      S-4
<PAGE>


ONEOK Capital Trust I is offering its preferred securities to you.

   Each preferred security represents an undivided beneficial interest in the
assets of ONEOK Capital Trust I. The junior subordinated debentures will be the
sole asset of ONEOK Capital Trust I. Each preferred security will entitle the
holder to receive quarterly cash distributions as described in this prospectus
supplement. ONEOK Capital Trust I is offering preferred securities at a price
of $        for each $25 liquidation amount of preferred securities.

You will be entitled to receive quarterly distributions on your preferred
securities.

   You are entitled to receive cumulative cash distributions on your preferred
securities at an annual rate of     % of the liquidation amount of $25 per
preferred securities. The liquidation amount is the amount that you are
entitled to receive if ONEOK Capital Trust I is terminated and its assets are
liquidated and distributed to the holders of the trust securities.
Distributions will accumulate from the date ONEOK Capital Trust I issues the
preferred securities and will be paid quarterly in arrears on      ,      ,
      and       of each year beginning      , 1999.

ONEOK will have the right to defer quarterly distributions on your preferred
securities.

   So long as no event of default under the junior subordinated indenture has
occurred and is continuing, ONEOK can, on one or more occasions, defer interest
payments on the junior subordinated debentures for up to 20 consecutive
quarterly periods. A deferral of interest payments cannot extend, however,
beyond the maturity date of the junior subordinated debentures, which is
      ,     . Once ONEOK makes all deferred interest payments on the junior
subordinated debentures, with accrued interest, it can again defer interest
payments on the junior subordinated debentures for up to 20 consecutive
quarterly periods.

   If ONEOK defers interest payments on the junior subordinated debentures,
ONEOK Capital Trust I will also defer distributions on the preferred
securities. During any deferral period, distributions will continue to accrue
on the preferred securities at an annual rate of     % of the liquidation
amount. Also, the deferred distributions will themselves accrue interest at an
annual rate of     %, to the extent permitted by law.

   During any period in which ONEOK defers interest payments on the junior
subordinated debentures, ONEOK, with limited exceptions, will be not permitted
to:

  .  pay a dividend or make any distributions on its capital stock or redeem,
     purchase, acquire or make a liquidation payment on any of its capital
     stock; or

  .  make an interest, principal or premium payment on, or repurchase or
     redeem, any of its debt securities that rank equally with or junior to
     the junior subordinated debentures, or make any guarantee payments on
     any guarantee by it of debt securities of any of its subsidiaries if the
     guarantee is equal to or junior in right of payment to the junior
     subordinated debentures.

You will have the following tax consequences if ONEOK Capital Trust I defers
quarterly distributions.

   If ONEOK defers payments of interest on the junior subordinated debentures,
the junior subordinated debentures will, from the time of deferral, be treated
as having been reissued with original issue discount for United States federal
income tax purposes. This means that you will be required to accrue interest
income and include the amounts of this income in your gross income for United
States federal income tax purposes even though you will not have received any
cash distributions relating to this interest income, and even though you may
use the cash method of accounting. See "Taxation--Interest and Original Issue
Discount."

                                      S-5
<PAGE>


Your preferred securities will have the following maturity and redemption
provisions.

   ONEOK Capital Trust I must redeem all of the outstanding preferred
securities and common securities when the junior subordinated debentures are
paid at maturity on       ,     . If ONEOK redeems any junior subordinated
debentures before their maturity, ONEOK Capital Trust I must use the cash it
receives from the redemption to redeem, on a pro rata basis between the
preferred securities and the common securities, the preferred securities and
common securities having a combined liquidation amount equal to the principal
amount of the junior subordinated debentures redeemed. The particular preferred
securities to be redeemed will be selected by the property trustee on a basis
that it deems to be fair and appropriate, including, without limitation, by
lot.

   ONEOK can redeem some or all of the junior subordinated debentures before
their maturity at 100% of their principal amount on one or more occasions any
time on or after       ,     . ONEOK also has the option to redeem the junior
subordinated debentures, in whole, but not in part, at any time if specific
changes in tax or investment company law occur and other conditions are
satisfied. These changes are described under "Description of the Preferred
Securities--Special Event Redemption or Distribution."

   Upon any redemption, you will receive the redemption price, which is equal
to the liquidation amount of $25 per preferred security plus any accrued and
unpaid distributions to the date of redemption.

The junior subordinated debentures may be distributed to you.

   ONEOK has the right to terminate ONEOK Capital Trust I at any time. If ONEOK
terminates ONEOK Capital Trust I, ONEOK Capital Trust I will liquidate by
distributing the junior subordinated debentures to holders of the preferred
securities and common securities on a pro rata basis. If the junior
subordinated debentures are distributed, ONEOK will use its best efforts to
list the junior subordinated debentures on the New York Stock Exchange or any
other exchange on which the preferred securities are then listed. For a
discussion of ONEOK's ability to distribute the junior subordinated debentures,
see "Description of the Preferred Securities--Exchange of Junior Subordinated
Debentures for Preferred Securities" and "--Liquidation Distribution Upon
Dissolution."

ONEOK will fully and unconditionally guarantee the preferred securities.

   ONEOK will fully and unconditionally guarantee the preferred securities
based on its obligations under:

  .  the junior subordinated indenture to make payments on the junior
     subordinated debentures;

  .  the preferred securities guarantee, which guarantees the obligation of
     ONEOK Capital Trust I to pay distributions on the preferred securities,
     but only to the extent ONEOK Capital Trust I has funds legally and
     immediately available to make those distributions; and

  .  the trust agreement of ONEOK Capital Trust I and the agreement as to
     expenses and liabilities between ONEOK and ONEOK Capital Trust I.

    ONEOK's obligations under the preferred securities guarantee are:

  .  subordinate and junior in right of payment to its other liabilities;

  .  equal in rank to ONEOK's most senior preferred stock; and

  .  senior to its common stock.

                                      S-6
<PAGE>


You have the following rights upon liquidation of ONEOK Capital Trust I.

   In the event of the voluntary or involuntary liquidation, dissolution,
winding up or termination of ONEOK Capital Trust I, the holders of the
preferred securities will be entitled to receive an amount equal to the
liquidation amount of their preferred securities, plus accrued and unpaid
distributions on the preferred securities, including any interest on the unpaid
distributions, to the date of payment. If, however, junior subordinated
debentures are distributed to the holders of the preferred securities upon
liquidation, dissolution, winding up or termination, the liquidation amount
will not be paid. See "Description of the Preferred Securities--Liquidation
Distribution Upon Dissolution."

You have limited voting rights as a preferred security holder.

   Holders of preferred securities have limited voting rights and will not be
able to appoint, remove or replace any of the trustees, or to increase or
decrease the number of trustees. In general, only ONEOK has these rights. See
"Description of the Preferred Securities--Voting Rights."

Your preferred securities will not be represented by certificates.

   The preferred securities will be represented by one or more global
securities that will be deposited with and registered in the name of The
Depository Trust Company or its nominee. This means that you will not receive a
certificate for your preferred securities and that your broker will maintain
your position in the preferred securities. ONEOK expects that the preferred
securities will be ready for delivery through The Depository Trust Company on
or about       , 1999.

We expect that the preferred securities will be listed on the New York Stock
Exchange.

   Application will be made to list the preferred securities on the New York
Stock Exchange. If approved, trading of the preferred securities is expected to
begin within 30 days after they are first issued.

The proceeds of this offering will be used by ONEOK Capital Trust I and ONEOK
as follows.

   The proceeds of the sale of the preferred securities will be invested by
ONEOK Capital Trust I in junior subordinated debentures of ONEOK. The proceeds
from the issuance of the junior subordinated debentures will be used by ONEOK
to refinance short-term indebtedness incurred to finance the acquisition of the
Oklahoma assets of Koch Midstream Enterprises on May 1, 1999 and to refinance
other short-term indebtedness incurred for general corporate purposes.

   The following table shows the ratios of earnings to fixed charges and
earnings to combined fixed charges and preferred stock dividend requirements
for ONEOK for the periods indicated.

<TABLE>
<CAPTION>
                          Nine Months Ended
                               May 31,            For the Years Ended August 31,
                         -------------------- ---------------------------------------
                         Southwest            Southwest
                            Gas                  Gas
                          Merger               Merger
                         Pro Forma Historical Pro Forma          Historical
                         --------- ---------- --------- -----------------------------
                           1999       1999      1998    1998  1997  1996  1995  1994
                         --------- ---------- --------- ----- ----- ----- ----- -----
<S>                      <C>       <C>        <C>       <C>   <C>   <C>   <C>   <C>
Ratio of earnings to
 fixed charges..........   2.37x     5.44x      1.89x   5.50x 3.51x 3.28x 2.70x 2.52x
Ratio of earnings to
 combined fixed charges
 and preferred stock
 dividend requirements..   1.78x     2.47x      1.50x   2.52x 3.48x 3.24x 2.67x 2.49x
</TABLE>

   Merger pro forma information gives effect to the proposed merger transaction
with Southwest Gas and is presented as if the proposed merger transaction had
occurred as of the beginning of the applicable period.

                                      S-7
<PAGE>


   For purposes of computing the ratio of earnings to fixed charges, "earnings"
consists of net income plus fixed charges and income taxes. "Fixed charges"
consists of interest charges, the representative interest portion of operating
leases, preferred securities distributions of a subsidiary and the amortization
of debt issue costs.

   For purposes of computing the ratio of earnings to combined fixed charges
and preferred dividend requirements, "earnings" consists of net income plus
fixed charges and income taxes. "Fixed charges" consists of interest charges,
the amortization of debt issue costs, the representative interest portion of
operating leases and preferred securities distributions of a subsidiary.
"Preferred stock dividend requirements" consists of the pre-tax preferred stock
dividend requirement.

                                      S-8
<PAGE>

                                  RISK FACTORS

   You should carefully read the following risk factors and the other sections
of this prospectus supplement and the accompanying prospectus before purchasing
any preferred securities.

   If ONEOK does not make payments on the junior subordinated debentures, ONEOK
Capital Trust I will be unable to make payments on the preferred securities and
the preferred securities guarantee will not apply.

   The ability of ONEOK Capital Trust I to pay timely distributions on the
preferred securities, the redemption price of the preferred securities and the
liquidation amount of $25 per preferred security is solely dependent upon the
ability of ONEOK to make related payments on the junior subordinated debentures
when due. If ONEOK defaults on its obligation to pay principal of or interest
on the junior subordinated debentures, ONEOK Capital Trust I will not have
sufficient funds to pay distributions, the redemption price or the liquidation
amount. In that case, you will not be able to rely upon the preferred
securities guarantee for payment of these amounts because the preferred
securities guarantee only applies if ONEOK makes a payment of principal or
interest on the junior subordinated debentures.

   Instead, you:

  .  may directly sue ONEOK or seek other remedies to collect your share of
     payments owed; or

  .  may rely on the indenture trustee to enforce ONEOK Capital Trust I's
     rights under the junior subordinated indenture, as a holder of the
     junior subordinated debentures.

   ONEOK's obligations under the preferred securities guarantee and the junior
subordinated debentures are subordinate to other ONEOK obligations.

   ONEOK's obligations under the preferred securities guarantee are unsecured
and will rank in priority of payment:

  .  subordinate and junior to all of ONEOK's other indebtedness, liabilities
     and obligations, including the junior subordinated debentures;

  .  equal to ONEOK's most senior preferred stock; and

  .  senior to ONEOK's common stock.

   This means that ONEOK cannot make any payments on the preferred securities
guarantee if it defaults on a payment of any of its other liabilities. In
addition, in the event of the bankruptcy, liquidation or dissolution of ONEOK,
its assets would be available to pay its obligations under the preferred
securities guarantee only after ONEOK made all payments on its other senior
indebtedness.

   ONEOK's obligations under the junior subordinated debentures are unsecured
and will rank junior in priority of payment to ONEOK's senior indebtedness.
This means that ONEOK cannot make payments on the junior subordinated
debentures if it defaults on a payment of senior indebtedness and does not cure
that default within the applicable grace period or if the senior indebtedness
becomes immediately due because of a default and has not yet been paid in full.
At May 31, 1999, the aggregate amount of ONEOK's senior indebtedness was
approximately $938 million. ONEOK's obligations under the junior subordinated
debentures will also be effectively subordinated to all existing and future
liabilities and obligations of ONEOK's subsidiaries.

   The preferred securities, the junior subordinated debentures and the
preferred securities guarantee do not limit the ability of ONEOK or any of its
subsidiaries to incur additional indebtedness, liabilities and obligations,
including indebtedness, liabilities and obligations that rank senior to the
junior subordinated debentures and the preferred securities guarantee.

                                      S-9
<PAGE>

   For more information on ONEOK's obligations under the preferred securities
guarantee and the junior subordinated debentures, see "Description of the
Preferred Securities Guarantees" and "Description of the Junior Subordinated
Debentures" in the accompanying prospectus.

   You may not be able to directly enforce rights against ONEOK if an event of
default occurs.

   You may have to rely on the property trustee under the trust agreement of
ONEOK Capital Trust I to enforce your rights if an event of default under the
junior subordinated indenture occurs.

   If an event of default under the junior subordinated indenture occurs and is
continuing, that will also be an event of default under the preferred
securities. In that case, the holders of the preferred securities would have to
rely on the enforcement against ONEOK by the property trustee of its rights as
holder of the junior subordinated debentures. The holders of at least 25% in
liquidation amount of the preferred securities will have the right to direct
the property trustee to enforce its rights. However, if the property trustee
does not enforce its rights any record holder would then, to the extent
permitted by applicable law, have to take action directly against ONEOK to
enforce the property trustee's rights. In addition, if an event of default
under the preferred securities occurs that is attributable to ONEOK's failure
to pay interest or principal on the junior subordinated debentures, a record
holder of the preferred securities may proceed directly against ONEOK. The
holders of preferred securities will not be able to exercise directly any other
remedies available to the holders of the junior subordinated debentures unless
the property trustee fails to do so. See "Description of the Preferred
Securities--Events of Default" in this prospectus supplement and "Description
of the Junior Subordinated Debentures--Events of Default" in the accompanying
prospectus for more information on your rights if an event of default occurs.

   Distributions on the preferred securities may be deferred. You may be
required to include interest in your taxable income before you receive cash.

   ONEOK has the right, in its sole discretion, to defer payments of interest
on the junior subordinated debentures by extending the interest payment period
from time to time on the junior subordinated debentures. Quarterly
distributions to the holders will also be deferred during any interest deferral
period. See "Description of the Preferred Securities--Distributions." Thus, it
is possible that you will not receive cash distributions for one or more
periods of up to 20 quarterly periods. If this occurs, during any deferral
period, you will still be required to include accrued interest in your income
for United States federal income tax purposes in the form of original issue
discount on the junior subordinated debentures held by ONEOK Capital Trust I
before you actually receive the cash distributions, even if you use the cash
method of accounting. You will also not receive the cash distribution related
to any accrued and unpaid interest from ONEOK Capital Trust I if you sell your
preferred securities before the end of any deferral period. While ONEOK will
take the position that original issue discount will not arise before any first
deferral period, it is possible that all income on the junior subordinated
debentures would be required to be accounted for as original issue discount.
Under those circumstances, stated interest would not separately be reported as
taxable income. See "Taxation" in this prospectus supplement for more
information regarding the tax consequences of the preferred securities.

   The price of the preferred securities may be impacted by the deferral of
interest payments on the junior subordinated debentures or the existence of the
right to defer.

   ONEOK has no current intention of deferring interest payments on the junior
subordinated debentures. However, if ONEOK exercises its right in the future,
the preferred securities may trade at a price that does not fully reflect the
value of the accrued but unpaid interest on the junior subordinated debentures.
If you sell your preferred securities during a deferral period, you may not
receive the same return on investment as someone else who continues to hold
preferred securities. In addition, the existence of ONEOK's right to defer
payments of interest on the junior subordinated debentures may mean that the
market price for the preferred securities, which represent an undivided
beneficial interest in the junior subordinated debentures, may be more volatile

                                      S-10
<PAGE>

than other securities that do not have these rights. See "Taxation" in this
prospectus supplement for more information regarding the tax consequences of
the preferred securities.

   Possible tax law changes could result in redemption of the preferred
securities.

   Enactment of tax proposals may allow ONEOK to exercise its right to redeem
the junior subordinated debentures, which would result in a mandatory
redemption of the preferred securities at the liquidation amount. From time to
time, the Clinton Administration has proposed tax law changes that would
generally deny interest deductions to a corporate issuer of debt securities if
the debt instrument has a term exceeding 15 years and if the debt instrument is
not reflected as indebtedness on the issuer's consolidated balance sheet. Other
proposed tax law changes would deny interest deductions if the debt instrument
had a term exceeding 20 years. No similar proposal was made in the Clinton
Administration's budget proposal released on February 1, 1999. Although it is
impossible to predict future proposals, prior proposals, if enacted into law,
would not have applied to securities with characteristics similar to the junior
subordinated debentures which were already issued and outstanding at the time
the legislation was proposed. However, if a future proposal of this sort were
to become effective in a form applicable to already issued and outstanding
securities, ONEOK could be precluded from deducting interest on the junior
subordinated debentures. Enactment of any such proposal might in turn allow
ONEOK to exercise its right to redeem the junior subordinated debentures, which
would result in a mandatory redemption of the preferred securities as described
under "Description of the Preferred Securities--Redemption" and "--Special
Event Redemption Distribution."

   The preferred securities may be redeemed at any time if adverse changes in
tax or investment company law occur.

   If adverse changes in tax or investment company law occur and are
continuing, and other conditions are satisfied, ONEOK has the right to redeem
the junior subordinated debentures, in whole, but not in part, at any time. Any
such redemption would cause a mandatory redemption of all preferred securities
and common securities at a redemption price equal to their stated liquidation
amount of $25, plus any accrued and unpaid distributions. See "Description of
the Preferred Securities--Special Event Redemption or Distribution."

   The junior subordinated debentures, and therefore the preferred securities,
may be redeemed at the option of ONEOK.

   At the option of ONEOK, the junior subordinated debentures may be redeemed,
in whole, at any time, or in part, from time to time, on or after         ,
    , at a redemption price equal to the principal amount to be redeemed plus
any accrued and unpaid distributions, including interest to the date of
redemption. See "Description of the Junior Subordinated Debentures--Optional
Redemption." You should assume that ONEOK will exercise its redemption option
if ONEOK is able to refinance at a lower interest rate or it is otherwise in
the interest of ONEOK to redeem the junior subordinated debentures. If the
junior subordinated debentures are redeemed, ONEOK Capital Trust I must redeem,
on a pro rata basis, the preferred securities and common securities having an
aggregate liquidation amount equal to the aggregate principal amount of junior
subordinated debentures to be redeemed. See "Description of the Preferred
Securities--Redemption."

   ONEOK may terminate ONEOK Capital Trust I at any time.

   ONEOK has the right to terminate ONEOK Capital Trust I at any time. If ONEOK
decides to exercise its right to terminate the trust, ONEOK Capital Trust I
will liquidate by distributing the junior subordinated debentures to holders of
the preferred securities and the common securities on a pro rata basis.

   ONEOK has no current intention of causing the termination of ONEOK Capital
Trust I and distributing the junior subordinated debentures. ONEOK anticipates
that it would consider exercising this right in the event that expenses
associated with maintaining ONEOK Capital Trust I were substantially greater
than currently

                                      S-11
<PAGE>

expected such as if specific changes in tax law or investment company law
occurred. See "Description of the Preferred Securities--Special Event
Redemption or Distribution." ONEOK cannot predict the other circumstances under
which this right would be exercised.

   Although ONEOK intends to use its best efforts to list the junior
subordinated debentures on the New York Stock Exchange, or any other exchange
on which the preferred securities are then listed, if they are distributed, we
cannot assure you that the junior subordinated debentures will be approved for
listing or that a trading market will exist for those securities.

   There can be no assurance as to the market prices for the preferred
securities or the junior subordinated debentures.

   There can be no assurance as to the market prices for the preferred
securities or the junior subordinated debentures that may be distributed in
exchange for preferred securities upon a termination of ONEOK Capital Trust I.
Accordingly, the preferred securities that an investor may purchase, whether
pursuant to the offer made by this prospectus supplement or in the secondary
market, or the junior subordinated debentures that a holder of preferred
securities may receive upon a termination of ONEOK Capital Trust I, may trade
at a discount to the price that the investor paid to purchase the preferred
securities offered by this prospectus supplement. As a result of ONEOK's right
to defer interest payments on the junior subordinated debentures, the market
price of the preferred securities, which represent undivided beneficial
ownership interests in ONEOK Capital Trust I, the assets of which consist of
the junior subordinated debentures, may be more volatile than the market prices
of other securities that are not subject to such optional deferrals.

   You should consider an investment in preferred securities to be a possible
investment in the junior subordinated debentures.

   Because you may receive junior subordinated debentures upon termination of
ONEOK Capital Trust I, you must also make an investment decision with regard to
the junior subordinated debentures. You should carefully review all the
information regarding the junior subordinated debentures contained or
incorporated by reference in this prospectus supplement and the accompanying
prospectus. Under "Taxation--Distribution of Junior Subordinated Debentures to
Holders of Preferred Securities" we discuss applicable United States federal
income tax consequences of a distribution of junior subordinated debentures.

   Voting rights of preferred security holders are very limited.

   Holders of preferred securities have limited voting rights and will not be
able to appoint, remove or replace any of the trustees, or to increase or
decrease the number of trustees. In general, only ONEOK has these rights. See
"Description of the Preferred Securities--Voting Rights" in this prospectus
supplement for more information on your limited voting rights.

                                      S-12
<PAGE>

   The following information concerning ONEOK, ONEOK Capital Trust I, the
preferred securities, the junior subordinated debentures and the preferred
securities guarantee is in addition to, and should be read in conjunction with,
the information contained in the accompanying prospectus. Capitalized terms in
this prospectus supplement have the same meanings as in the accompanying
prospectus.

                                     ONEOK

   ONEOK and its subsidiaries engage in several aspects of the energy business.
ONEOK purchases, gathers, compresses, transports and stores natural gas for
distribution to consumers. ONEOK transports gas for others and leases pipeline
capacity to others for use in transporting gas. ONEOK drills for and produces
gas and oil, extracts and sells natural gas liquids, and engages in the gas
marketing business. In addition, ONEOK leases and operates a headquarters
office building (leasing space it does not use to others) and owns and operates
a related parking facility. As a regulated natural gas utility, ONEOK
distributes natural gas to approximately 1.4 million customers in the states of
Oklahoma and Kansas.

   ONEOK has agreed to acquire Southwest Gas by merger for cash of
approximately $917 million. ONEOK will be the survivor of the proposed merger
transaction. Southwest Gas is a regulated natural gas utility that distributes
natural gas to      customers in the states of Nevada, Arizona and California.
The proposed merger is subject to customary conditions, including approval by
the shareholders of Southwest Gas and the receipt of governmental and other
authorizations, and is expected to close later in 1999. ONEOK has received the
requisite approvals from the Public Service Commission of Nevada and expects to
receive the requisite approvals from the States of Arizona and California by
the end of the third quarter of 1999. It is possible that regulatory approvals
that are obtained will contain conditions or limitations that will adversely
affect the results of operations of the combined company. Unaudited pro forma
combined condensed financial data giving effect to the proposed merger are
included in ONEOK's current report on Form 8-K dated July 12, 1999, which is
incorporated herein by reference.

   ONEOK's principal executive offices are located at 100 West Fifth Street,
Tulsa, Oklahoma 74103, and its telephone number is (918) 588-7000.

   For purposes of the foregoing description, all references to ONEOK refer
collectively to ONEOK, Inc. and its operating subsidiaries, unless the context
otherwise requires.

                             ONEOK CAPITAL TRUST I

   ONEOK Capital Trust I is a statutory business trust created under Delaware
law pursuant to the filing of a certificate of trust with the Secretary of
State of the State of Delaware on July 12, 1999. ONEOK Capital Trust I's
business is defined in a trust agreement, executed by ONEOK, as depositor,
           , as the Delaware trustee, and            , as the property trustee
thereunder. This trust agreement will be amended and restated in its entirety
on the date that ONEOK Capital Trust I issues the preferred securities.
References to the trust agreement in this prospectus supplement are to the
amended and restated trust agreement. The trust agreement has been qualified
under the Trust Indenture Act of 1939. ONEOK Capital Trust I exists for the
exclusive purposes of (1) issuing the preferred securities and the common
securities (collectively referred to in this prospectus supplement as the trust
securities) representing undivided, beneficial interests in the assets of ONEOK
Capital Trust I, (2) investing the gross proceeds of the trust securities in
ONEOK's junior subordinated debentures and (3) engaging in only those other
activities necessary, appropriate, convenient or incidental thereto. ONEOK
Capital Trust I has a term of approximately    years, but may terminate earlier
as provided in the trust agreement.

                                      S-13
<PAGE>

   Upon issuance of the preferred securities, the purchasers thereof will own
all of the preferred securities. ONEOK will acquire all of the common
securities, which will have an aggregate liquidation amount equal to
approximately 3% of the total capital of ONEOK Capital Trust I. The common
securities will rank equally, and payments will be made thereon pro rata, with
the preferred securities, except that upon the occurrence and continuance of an
event of default under the junior subordinated indenture, the rights of the
holders of common securities to payment in respect of distributions and
payments upon liquidation, redemption and otherwise will be subordinated to the
rights of the holders of the preferred securities.

   ONEOK Capital Trust I's business and affairs will be conducted by the
property trustee, the administrative trustee and the Delaware trustee
(collectively referred to in this prospectus supplement as the securities
trustees), which will be appointed by ONEOK, as the holder of the common
securities. A direct or indirect wholly owned subsidiary of ONEOK initially
will serve as administrative trustee.            will serve as property trustee
and will hold legal title to the junior subordinated debentures issued by ONEOK
on behalf of ONEOK Capital Trust I and the holders of the trust securities.
           will serve as Delaware trustee. In specific circumstances, the
holders of a majority in liquidation amount of the preferred securities will be
entitled to appoint a substitute property trustee. See "Description of the
Preferred Securities--Voting Rights."

   The property trustee will hold legal title to the junior subordinated
debentures for the benefit of ONEOK Capital Trust I and the holders of the
trust securities and will have the power to exercise all rights, powers and
privileges under the junior subordinated indenture as the holder of the junior
subordinated debentures. The property trustee will make payments of
distributions and payments on liquidation, redemption and otherwise to the
holders of the trust securities. Subject to the right of the holders of the
preferred securities to appoint a substitute property trustee in specific
instances, ONEOK, as the holder of all the common securities, will have the
right to appoint, remove or replace all the securities trustees.

   The junior subordinated debentures will constitute substantially all of the
assets of ONEOK Capital Trust I. Other assets that may constitute "Trust
Property" (as that term is defined in the trust agreement) include any cash on
deposit in, or owing to, the payment account as established under the trust
agreement, as well as any other property or assets held by the property trustee
pursuant to the trust agreement. In addition, ONEOK Capital Trust I may, from
time to time, receive cash pursuant to the agreement as to expenses and
liabilities between ONEOK and ONEOK Capital Trust I. Under the agreement as to
expenses and liabilities, ONEOK will guarantee the payment of any costs,
expenses or liabilities of ONEOK Capital Trust I, other than obligations on the
preferred securities.

   The rights of the holders of the preferred securities, including economic
rights, rights to information and voting rights, are as set forth in the trust
agreement, the Delaware Business Trust Act and the Trust Indenture Act. See
"Description of the Preferred Securities."

   ONEOK Capital Trust I's office and principal place of business are located
at 100 West Fifth Street, Tulsa, Oklahoma 74103, and its telephone number is
(918) 588-7000.

                 ACCOUNTING TREATMENT OF ONEOK CAPITAL TRUST I

   For financial reporting purposes, ONEOK Capital Trust I will be treated as a
subsidiary of ONEOK and, accordingly, its accounts will be included in the
consolidated financial statements of ONEOK. The preferred securities will be
presented as a separate line item in the consolidated balance sheet of ONEOK,
and appropriate disclosures concerning the preferred securities, the preferred
securities guarantee and the junior subordinated debentures will be included in
the notes to the consolidated financial statements. For financial reporting
purposes, ONEOK will record distributions payable on the preferred securities
as an expense.

              SELECTED CONSOLIDATED FINANCIAL INFORMATION OF ONEOK

   The following selected consolidated financial information is qualified by
reference to, and should be read in conjunction with, ONEOK's consolidated
financial statements and accompanying notes and "Management's Discussion and
Analysis of Financial Condition and Results of Operations" included in ONEOK's
Annual

                                      S-14
<PAGE>

Report on Form 10-K for the fiscal year ended August 31, 1998, which is
incorporated by reference in the accompanying prospectus. The selected
consolidated statement of income data for the years ended August 31, 1996, 1997
and 1998 and the selected consolidated statement of financial condition data as
of August 31, 1997 and 1998 are derived from ONEOK's audited consolidated
financial statements, which are incorporated by reference in the accompanying
prospectus. The selected unaudited financial information as of and for the nine
months ended May 31, 1998 and 1999 should be read in conjunction with ONEOK's
audited consolidated financial statements, accompanying notes and "Management's
Discussion and Analysis of Financial Conditions and Results of Operations"
contained in the Form 10-K referred to above and ONEOK's unaudited consolidated
financial statements and accompanying notes contained in ONEOK's Quarterly
Report on Form 10-Q for the quarter ended May 31, 1999, which is also
incorporated by reference in the accompanying prospectus. Such unaudited
information reflects, in the opinion of management, all adjustments, consisting
of normal recurring adjustments, which ONEOK considers necessary for a fair
presentation of its financial position and results of operations for these
periods. Operating results for the nine months ended May 31, 1999 are not
necessarily indicative of the results that may be expected for the entire year
ending August 31, 1999. The selected consolidated statement of financial
condition data as of August 31, 1994, 1995, 1996 and the selected consolidated
statement of income data for the years ended August 31, 1994 and 1995 are
derived from audited consolidated financial statements of ONEOK that are not
included or incorporated by reference in the accompanying prospectus.

<TABLE>
<CAPTION>
                          Nine Months Ended
                               May 31,                   Years Ended August 31,
                          ------------------  ------------------------------------------------
                            1999      1998      1998      1997      1996      1995      1994
                          --------  --------  --------  --------  --------  --------  --------
                                   (dollars in millions, except per share data)
<S>                       <C>       <C>       <C>       <C>       <C>       <C>       <C>
Operating revenues......  $1,385.7  $1,465.6  $1,820.8  $1,161.9  $1,218.8  $  954.2  $  784.1
Operating income........     200.3     195.1     188.9     128.1     115.5     105.5      92.0
Net income..............     104.0     113.3     101.8      59.3      52.8      42.8      36.2
Total assets (period
 end)...................   2,935.2   2,442.5   2,422.5   1,237.4   1,219.9   1,181.2   1,148.1
Long-term debt (period
 end)...................     541.4     329.3     329.3     347.1     351.9     363.9     376.9
Diluted earnings per
 common share...........      2.01      2.59      2.23      2.13      1.93      1.58      1.34
Dividends per common
 share..................       .93       .90      1.20      1.20      1.18      1.12      1.11
Percent of payout.......      46.3%     34.7%     53.8%     56.2%     61.1%     70.9%     82.8%
Common equity per share
 (period end)...........  $  20.52  $  19.92  $  19.01  $  16.47  $  15.21  $  14.38  $  13.88
Return on common equity.     11.72%    15.18%    12.46%    12.75%    12.64%    10.90%     9.65%
</TABLE>

   The following table sets forth ONEOK's capitalization as of May 31, 1999 and
its capitalization, as adjusted to reflect the issuance of the preferred
securities and the use of proceeds to as set forth under "Use of Proceeds," net
of underwriting commissions and other issuance expenses. The following data is
qualified in its entirety by reference to, and should be read together with,
the detailed information and financial statements appearing in the documents
incorporated by reference in this prospectus supplement and the accompanying
prospectus.

<TABLE>
<CAPTION>
                                                              May 31, 1999
                                                          ---------------------
                                                                         As
                                                            Actual    Adjusted
                                                          ---------- ----------
                                                               (dollars in
                                                               thousands)
<S>                                                       <C>        <C>
Long-term debt (excluding current portion)..............  $  524,558 $
ONEOK obligated mandatorily redeemable preferred
 securities of ONEOK's subsidiary ONEOK Capital Trust I.           0
Convertible preferred stock.............................     569,070    569,070
Common shareholders' equity.............................     648,555    648,555
                                                          ---------- ----------
  Total capitalization..................................   1,742,183
                                                          ========== ==========
Short-term notes payable (including current portion of
 long-term debt)........................................  $  413,817 $
                                                          ========== ==========
</TABLE>

                                USE OF PROCEEDS

   ONEOK Capital Trust I will invest all of the proceeds from the sale (which,
assuming an initial offering price equal to the liquidation amount, are
estimated to be approximately $     million) in junior subordinated debentures
of ONEOK. The proceeds from the issuance of the junior subordinated debentures
will be used by

                                      S-15
<PAGE>

ONEOK to refinance short-term indebtedness that was used to finance the
acquisition of the Oklahoma assets of Koch Midstream Enterprises in May 1999
and to refinance other short-term indebtedness incurred for general corporate
purposes. The weighted average annual interest rate of this short-term
indebtedness was 5.24% as of May 31, 1999.

                    DESCRIPTION OF THE PREFERRED SECURITIES

   The preferred securities will be issued pursuant to the terms of the trust
agreement. The trust agreement has been qualified as an indenture under the
Trust Indenture Act. The property trustee will act as the indenture trustee for
the trust agreement and the preferred securities guarantee for purposes of
compliance with the provisions of the Trust Indenture Act. The terms of the
preferred securities will include those stated in the trust agreement, the
Delaware Business Trust Act and those made part of the trust agreement by the
Trust Indenture Act. The following summary of the principal terms and
provisions of the preferred securities does not purport to be complete and is
subject to, and qualified in its entirety by reference to, the trust agreement,
as well as the Delaware Business Trust Act and the Trust Indenture Act. The
form of the trust agreement is filed as an exhibit to the registration
statement of which this prospectus supplement and the accompanying prospectus
are a part.

General

   The trust agreement authorizes the administrative trustee, on behalf of
ONEOK Capital Trust I, to issue the trust securities, which will consist of the
preferred securities and the common securities. The preferred securities will
represent preferred undivided beneficial interests in the assets of ONEOK
Capital Trust I. The common securities will represent common undivided
beneficial interests in the assets of ONEOK Capital Trust I. All of the common
securities will be owned by ONEOK. The common securities rank equally, and
payments will be made thereon on a pro rata basis, with the preferred
securities, except that upon the occurrence of an event of default under the
junior subordinated indenture, the rights of the holders of the common
securities to receive payment of periodic distributions and payments upon
liquidation, redemption and otherwise will be subordinated to the rights of the
holders of the preferred securities.

   The trust agreement does not permit the issuance by ONEOK Capital Trust I of
any securities other than the trust securities or the incurrence of any
indebtedness by ONEOK Capital Trust I.

   The property trustee under the trust agreement will own and hold the junior
subordinated debentures for the benefit of ONEOK Capital Trust I and the
holders of the trust securities.

   The payment of distributions out of money held by ONEOK Capital Trust I, and
payments upon redemption of the preferred securities or liquidation of ONEOK
Capital Trust I, are guaranteed by ONEOK on a subordinated basis as described
under "Description of the Preferred Securities Guarantees" in the accompanying
prospectus. The preferred securities guarantee does not cover payment of
distributions on the preferred securities when ONEOK Capital Trust I does not
have legally and immediately available funds sufficient to make those
distributions. In that event, the holders of preferred securities must rely
upon the property trustee to enforce its rights under the junior subordinated
debentures or, if an event of default under the junior subordinated indenture
has occurred and is continuing and the indenture trustee fails or the holders
of not less than 25% of the junior subordinated debentures fail to declare the
principal of all of the junior subordinated debentures to be immediately due
and payable, the holders of at least 25% in liquidation amount of the preferred
securities then outstanding have the right by notice in writing to ONEOK and
the indenture trustee to declare the principal of the junior subordinated
debentures immediately due in a legal proceeding directly against ONEOK,
without first instituting a legal proceeding against the property trustee or
any other person or entity, for enforcement of payment to the holders of
principal of or interest on the junior subordinated debentures having a
principal amount equal to the aggregate stated liquidation amount of the
preferred securities of the requesting holders. In addition, if an event of
default under the preferred securities occurs that is attributable to ONEOK's
failure to pay interest or principal on the junior subordinated debentures, any
record holder of preferred securities may proceed directly against ONEOK for
the payment of principal or interest due to such holder.

                                      S-16
<PAGE>

   The above mechanisms and obligations, together with ONEOK's obligations
under the agreement as to expenses and liabilities with ONEOK Capital Trust I,
constitute a full and unconditional guarantee by ONEOK of payments due on the
preferred securities.

Distributions

   Distributions on the preferred securities will be fixed at    % per year of
their liquidation amount and will accrue from the date of original issue of the
preferred securities. Except in the event of an extension period (as described
below), distributions will be payable quarterly in arrears on         ,
  ,            and            in each year, commencing       , 1999. In the
event that any date on which distributions are to be made on the preferred
securities is not a business day, then payment of the distributions payable on
that date will be made on the next succeeding day that is a business day (and
without any interest or other payment in respect of the delay). If, however,
the business day is in the next succeeding calendar year, the payment will be
made on the immediately preceding business day. A business day is any day other
than a Saturday or Sunday, a day on which banks in The City of New York are
authorized or obligated by law or executive order to remain closed or a day on
which the principal corporate trust office of the property trustee or the
indenture trustee is closed for business.

   Distributions payable on any distribution date will be payable to the
holders of record on the record date for that distribution date, which is the
business day immediately prior to the distribution date, or, if the preferred
securities do not remain in book-entry only form, the fifteenth calendar day
preceding the distribution date. Subject to any applicable laws and regulations
and the provisions of the trust agreement, each distribution will be made as
described under "--Book-Entry Only Issuance--The Depository Trust Company"
below. The amount of distributions payable for any period will be computed on
the basis of a 360-day year of twelve 30-day months.

   So long as no event of default has occurred and is continuing under the
junior subordinated indenture, ONEOK has the right under the junior
subordinated indenture to defer payments of interest on the junior subordinated
debentures by extending the interest payment period from time to time on the
junior subordinated debentures. This would defer quarterly distributions on the
preferred securities during the extension period. Deferred installments of
interest on the junior subordinated debentures, and deferred distributions on
the preferred securities, will bear interest, compounded quarterly, at a rate
per annum equal to the rate on the preferred securities, to the extent
permitted by applicable law. If distributions on the preferred securities are
deferred, the deferred distributions and accrued interest thereon shall be
paid, if funds are legally available therefor, to holders of record of the
preferred securities as they appear on the books and records of ONEOK Capital
Trust I on the record date next following the termination of the extension
period. See "Description of the Junior Subordinated Debentures--Interest" and
"--Option to Extend Interest Payment Period."

   Distributions on the preferred securities due on a scheduled distribution
date must be paid on that distribution date to the extent that ONEOK Capital
Trust I has funds legally and immediately available for the payment of those
distributions. ONEOK Capital Trust I's funds available for distribution to the
holders of the preferred securities will be limited to payments received on the
junior subordinated debentures. See "Description of the Junior Subordinated
Debentures."

Redemption

   The preferred securities are subject to mandatory redemption upon repayment
of the junior subordinated debentures at maturity or their earlier redemption.
The junior subordinated debentures will mature on       ,      and may be
redeemed, in whole at any time or in part from time to time, without premium,
at the option of ONEOK, at any time on or after         ,      or at any time
in whole, but not in part, upon the occurrence of a Special Event described
below. Upon the repayment of the junior subordinated debentures, whether at
maturity or upon redemption, the proceeds must be applied simultaneously to
redeem a like amount of trust securities upon not less than 30 nor more than 60
days' notice, at a redemption price equal to their stated liquidation amount of
$25 per trust security, plus accrued and unpaid distributions thereon to the
date of payment. See "Description of the Junior Subordinated Debentures--
Optional Redemption."

                                      S-17
<PAGE>

   The preferred securities to be redeemed will be selected not more than 60
days prior to the redemption date by such method as the property trustee deems
fair and appropriate, including, without limitation, by lot, and which may
provide for the selection for redemption of portions (equal to $25 or integral
multiples thereof) of the aggregate liquidation amount of preferred securities
of a denomination larger than $25.

Special Event Redemption or Distribution

   Upon the occurrence of a Special Event, ONEOK will have the option to redeem
at any time the junior subordinated debentures in whole. This would cause ONEOK
Capital Trust I to redeem all of the preferred securities. A Special Event is
either an Investment Company Act Event or a Tax Event.

   An Investment Company Act Event means that ONEOK Capital Trust I has
received an opinion of counsel experienced in such matters, which may be
counsel to ONEOK, to the effect that, as a result of a change in law or
regulation or a written change in the interpretation or application of law or
regulation by any legislative body, court, governmental agency or regulatory
authority after the date of original issue of the preferred securities, there
is more than an insubstantial risk that ONEOK Capital Trust I is or will be
considered an "investment company" under the Investment Company Act of 1940.

   A Tax Event means that ONEOK Capital Trust I has received an opinion from
counsel experienced in such matters, which may be counsel to ONEOK, to the
effect that, as a result of (1) any amendment to, or change, including any
announced prospective change, in, the laws, or any regulations thereunder, of
the United States or any political subdivision or taxing authority thereof or
therein, or (2) any official administrative pronouncement or judicial decision
interpreting or applying those laws or regulations, which amendment or change
is effective or which pronouncement or decision is announced on or after the
date of original issue of the preferred securities, there is more than an
insubstantial risk that

  .  ONEOK Capital Trust I is, or within 90 days of the date of the opinion
     will be, subject to United States federal income tax on income received
     or accrued on the junior subordinated debentures;

  .  interest payable by ONEOK on the junior subordinated debentures is not,
     or within 90 days of the date of such opinion will not be, deductible by
     ONEOK, in whole or in part, for United States federal income tax
     purposes; or

  .  ONEOK Capital Trust I is, or within 90 days of the date of such opinion
     will be, subject to more than an insubstantial and immaterial amount of
     other taxes, duties or other governmental charges.

Exchange of Junior Subordinated Debentures for Preferred Securities

   ONEOK will have the right at any time to terminate ONEOK Capital Trust I
and, after satisfaction of liabilities to creditors of ONEOK Capital Trust I,
if any, cause the junior subordinated debentures to be distributed to the
holders of the preferred securities in liquidation of ONEOK Capital Trust I.
See "--Liquidation Distribution Upon Dissolution" below. This right is optional
and wholly within the discretion of ONEOK. Circumstances in which ONEOK might
decide to exercise this right could include but are not limited to the
occurrence of a Special Event, adverse tax consequences to ONEOK or ONEOK
Capital Trust I that are not within the definition of a Tax Event because they
do not result from an amendment, change, pronouncement or decision relating to
tax laws or regulations described in the definition of Tax Event, and changes
in the accounting requirements applicable to the preferred securities as
described under "Accounting Treatment of ONEOK Capital Trust I."

   If junior subordinated debentures are distributed to the holders of the
preferred securities, ONEOK will use its best efforts to have the junior
subordinated debentures listed on the New York Stock Exchange or on such other
exchange as the preferred securities are then listed. After the date for any
distribution of junior subordinated debentures upon termination of ONEOK
Capital Trust I, the preferred securities and the preferred

                                      S-18
<PAGE>

securities guarantee will no longer be deemed to be outstanding, certificates
representing junior subordinated debentures having an aggregate principal
amount equal to the aggregate liquidation amount of the trust securities will
be issued to the holders of certificates representing trust securities upon
surrender of such certificates for exchange, any certificates representing
preferred securities not so surrendered for exchange will be deemed to
represent junior subordinated debentures until such certificates are presented
to ONEOK or its agent for transfer or reissuance and all rights of holders of
trust securities will cease, except the right of the holders to receive junior
subordinated debentures upon surrender of their trust securities certificates.

   There can be no assurance as to the market prices for the preferred
securities or the junior subordinated debentures that may be distributed in
exchange for the preferred securities if a termination and liquidation of ONEOK
Capital Trust I were to occur. Accordingly, the preferred securities that an
investor may purchase, or the junior subordinated debentures that the investor
may receive on termination and liquidation of ONEOK Capital Trust I, may trade
at a discount to the price that the investor paid to purchase the preferred
securities offered hereby.

Redemption Procedures

   In the event that fewer than all of the trust securities are to be redeemed,
the aggregate liquidation amount of the trust securities to be redeemed will be
allocated 97% to the preferred securities and 3% to the common securities.

   Preferred securities redeemed on each redemption date will be redeemed at
their redemption price which equals their stated liquidation amount of $25 per
preferred security, plus accrued and unpaid distributions thereon to the date
of payment. Funds for redemption of the preferred securities will come from the
proceeds of the contemporaneous redemption or payment at maturity of junior
subordinated debentures. The redemption price of preferred securities will be
deemed payable on each redemption date only to the extent that ONEOK Capital
Trust I has funds legally and immediately available for payment of the
redemption price.

   If the property trustee gives a notice of redemption of preferred
securities, then, by 2:00 P.M., New York City time, on the redemption date,
subject to the immediately preceding paragraph, the property trustee will
irrevocably deposit with the securities depositary, so long as the preferred
securities are in book-entry only form, sufficient funds to pay the applicable
redemption price and will give the securities depositary irrevocable
instructions to pay the applicable redemption price. See "--Book-Entry Only
Issuance--The Depository Trust Company" below. If the preferred securities are
not in book-entry only form, the property trustee, subject to the immediately
preceding paragraph, will irrevocably deposit with the paying agent under the
trust agreement funds sufficient to pay the applicable redemption price and
will give the paying agent irrevocable instructions to pay the redemption price
to the holders of the preferred securities upon surrender of their preferred
securities certificates. Any notice of redemption will be irrevocable. If
notice of redemption has been given and funds deposited as required, then on
the date of such deposit, all rights of holders of preferred securities called
for redemption will cease, except the right of the holders to receive the
applicable redemption price and any distribution payable on or prior to the
redemption date. If any date fixed for redemption of preferred securities is
not a business day, then payment of the redemption price payable on that date
will be made on the next succeeding day which is a business day and without any
interest or other payment because of the delay, except that, if the business
day falls in the next calendar year, the payment will be made on the
immediately preceding business day. In the event that payment of the redemption
price is improperly withheld or refused and not paid either by ONEOK Capital
Trust I or by ONEOK pursuant to the preferred securities guarantee,
distributions on the preferred securities will continue to accrue at the then-
applicable rate, from the redemption date originally established by ONEOK
Capital Trust I for the preferred securities to the date the redemption price
is actually paid. See "--Events of Default" below, "Relationship among the
Preferred Securities, the Junior Subordinated Debentures and the Preferred
Securities Guarantee" herein and "Description of the Preferred Securities
Guarantees--Events of Default" in the accompanying prospectus.


                                      S-19
<PAGE>

   Subject to the foregoing and to applicable law, including, without
limitation, United States federal securities laws, ONEOK or any of its
affiliates may, at any time and from time to time, purchase outstanding
preferred securities by tender, in the open market or by private agreement.

Book-Entry Only Issuance--The Depository Trust Company

   The Depository Trust Company will act as the initial securities depositary
for the preferred securities. The preferred securities will be issued only as
fully registered securities registered in the name of Cede & Co., DTC's
nominee. One or more fully registered global preferred securities certificates
will be issued, representing in the aggregate the total number of preferred
securities, and will be deposited with DTC.

   DTC is a limited-purpose trust company organized under the New York Banking
Law, a "banking organization" within the meaning of the New York Banking Law, a
member of the Federal Reserve System, a "clearing corporation" within the
meaning of the New York Uniform Commercial Code, and a "clearing agency"
registered pursuant to the provisions of Section 17A of the Securities Exchange
Act of 1934, as amended. DTC holds securities that its participants
("Participants") deposit with DTC. DTC also facilitates the settlement among
Participants of securities transactions, such as transfers and pledges, in
deposited securities through electronic computerized book-entry changes in
Participants' accounts, thereby eliminating the need for physical movement of
securities certificates. Direct Participants include securities brokers and
dealers, banks, trust companies, clearing corporations and other organizations
("Direct Participants"). DTC is owned by a number of its Direct Participants
and by the New York Stock Exchange, the American Stock Exchange, Inc., and the
National Association of Securities Dealers, Inc. Access to the DTC system is
also available to others such as securities brokers and dealers, banks and
trust companies that clear through or maintain a custodial relationship with a
Direct Participant, either directly or indirectly ("Indirect Participants").
The rules applicable to DTC and its Participants are on file with the
Securities and Exchange Commission.

   Purchases of preferred securities within the DTC system must be made by or
through Direct Participants, which will receive a credit for the preferred
securities on DTC's records. The ownership interest of each actual purchaser of
preferred securities ("Beneficial Owner") is in turn to be recorded on the
Direct and Indirect Participants' records. Beneficial Owners will not receive
written confirmation from DTC of their purchases, but Beneficial Owners are
expected to receive written confirmations providing details of the
transactions, as well as periodic statements of their holdings, from the Direct
or Indirect Participants through which the Beneficial Owners purchased
preferred securities. Transfers of ownership interests in the preferred
securities are to be accomplished by entries made on the books of Participants
acting on behalf of Beneficial Owners. Beneficial Owners will not receive
certificates representing their ownership interests in preferred securities,
except in the event that use of the book-entry system for the preferred
securities is discontinued.

   DTC has no knowledge of the actual Beneficial Owners of the preferred
securities. DTC's records reflect only the identity of the Direct Participants
to whose accounts such preferred securities are credited, which may or may not
be the Beneficial Owners. The Participants will remain responsible for keeping
account of their holdings on behalf of their customers.

   Conveyance of notices and other communications by DTC to Direct
Participants, by Direct Participants to Indirect Participants, and by Direct
Participants and Indirect Participants to Beneficial Owners will be governed by
arrangements among them, subject to any statutory or regulatory requirements as
may be in effect from time to time.

   Redemption notices will be sent to DTC.

   Although voting with respect to the preferred securities is limited, in
those cases where a vote is required, neither DTC nor Cede & Co. will itself
consent or vote with respect to the preferred securities. Under its usual
procedures, DTC would mail an Omnibus Proxy to ONEOK Capital Trust I as soon as
possible after the record date. The Omnibus Proxy assigns Cede & Co.'s
consenting or voting rights to those Direct Participants to

                                      S-20
<PAGE>

whose accounts the preferred securities are credited on the record date
(identified in a listing attached to the Omnibus Proxy).

   Distribution payments on the preferred securities will be made to DTC. DTC's
practice is to credit Direct Participants' accounts on the relevant payment
date in accordance with their respective holdings shown on DTC's records unless
DTC has reason to believe that it will not receive payments on that payment
date. Payments by Participants to Beneficial Owners will be governed by
standing instructions and customary practices, as is the case with securities
held for the account of customers registered in "street name," and will be the
responsibility of the Participants and not of DTC, ONEOK Capital Trust I, any
trustee or ONEOK, subject to any statutory or regulatory requirements as may be
in effect from time to time. Payment of distributions to DTC is the
responsibility of ONEOK Capital Trust I, disbursement of such payments to
Direct Participants is the responsibility of DTC, and disbursement of such
payments to the Beneficial Owners is the responsibility of Direct and Indirect
Participants.

   Except as provided herein, a Beneficial Owner in a global preferred
securities will not be entitled to receive physical delivery of preferred
securities. Accordingly, each Beneficial Owner must rely on the procedures of
DTC to exercise any rights under the preferred securities. The laws of some
jurisdictions require that purchasers of securities take physical delivery of
securities in definitive form. These laws may impair the ability to transfer
beneficial interests in a global preferred securities.

   DTC may discontinue providing its services as securities depositary of the
preferred securities at any time by giving at least 90 days' prior written
notice to ONEOK Capital Trust I. If this happens, and a successor securities
depositary is not appointed, preferred securities certificates will be printed
and delivered to the holders of record. Additionally, ONEOK may decide to
discontinue use of the system of book-entry transfers through DTC or a
successor depositary. In that event, certificates for the preferred securities
will be printed and delivered to the holders of record.

   The information in this section concerning DTC and DTC's book-entry system
has been obtained from sources that ONEOK and ONEOK Capital Trust I believe to
be reliable, but ONEOK and ONEOK Capital Trust I take no responsibility for the
accuracy of these sources. ONEOK Capital Trust I has no responsibility for the
performance by DTC or its Participants of their respective obligations as
described herein or under the rules and procedures governing their respective
operations.

Liquidation Distribution Upon Dissolution

   Pursuant to the terms of the trust agreement, ONEOK Capital Trust I will
terminate on            ,      or earlier upon (1) the occurrence of a
Bankruptcy Event in respect of ONEOK, dissolution or liquidation of ONEOK or
entry of an order for dissolution of ONEOK Capital Trust I by a court of
competent jurisdiction; (2) the delivery of written direction to the property
trustee by ONEOK, at any time (which direction is optional and wholly within
the discretion of ONEOK) to terminate ONEOK Capital Trust I and distribute the
junior subordinated debentures to the holders of the trust securities in
liquidation of ONEOK Capital Trust I (see "--Exchange of Junior Subordinated
Debentures for Preferred Securities" above); or (3) the payment at maturity or
redemption of all of the junior subordinated debentures, and the consequent
payment of the trust securities.

   If ONEOK Capital Trust I terminates on           ,      or an early
termination occurs as described in clause (1) or (2) above, ONEOK Capital Trust
I will be liquidated, and the property trustee will distribute to each holder
of trust securities a like amount of junior subordinated debentures, unless the
distribution is determined by the property trustee not to be practical. In that
event, the holders will be entitled to receive, out of the assets of ONEOK
Capital Trust I available for distribution to holders after satisfaction of
liabilities to creditors, a liquidation distribution equal to the aggregate of
the liquidation amount of the trust securities, plus accumulated and unpaid
distributions thereon to the date of payment. If the liquidation distribution
can be paid only in part because ONEOK Capital Trust I has insufficient assets
available to pay in full the aggregate

                                      S-21
<PAGE>

liquidation distribution, then subject to the following sentence, the amounts
payable directly by ONEOK Capital Trust I on the trust securities will be paid
on a pro rata basis. The holder of the common securities will be entitled to
receive distributions upon any such dissolution pro rata with the holders of
the preferred securities, except that if an event of default has occurred and
is continuing under the junior subordinated indenture, the holders of preferred
securities will have a priority over the holder of common securities.

Events of Default

   Any one of the following events constitutes an "Event of Default" under the
trust agreement with respect to the trust securities:

  .  the occurrence of an "Event of Default" as defined in the junior
     subordinated indenture (each, a "Junior Subordinated Indenture Event of
     Default") (see "Description of the Junior Subordinated Debentures--
     Events of Default" in the accompanying prospectus); or

  .  default by ONEOK Capital Trust I in the payment of any distribution when
     it becomes due and payable, and the continuation of that default for a
     period of 30 days; or

  .  default by ONEOK Capital Trust I in the payment of any redemption price
     of any trust security when it becomes due and payable; or

  .  default in the performance, or breach, in any material respect, of any
     covenant or warranty of the securities trustees under the trust
     agreement (other than a covenant or warranty a default in the
     performance of which or the breach of which is described in clause (2)
     or (3) above), and continuation of the default or breach for a period of
     90 days after there has been given, by registered or certified mail, to
     the securities trustees by the holders of at least 25% in aggregate
     liquidation preference of the outstanding preferred securities a written
     notice specifying the default or breach and requiring it to be remedied
     and stating that the notice is a "Notice of Default" under the trust
     agreement; or

  .  the occurrence of events of bankruptcy or insolvency with respect to the
     property trustee and the failure by ONEOK to appoint a successor
     property trustee within 60 days.

   Within 90 days after the occurrence of any event of default under the trust
agreement or the junior subordinated indenture actually known to the property
trustee, the property trustee must transmit notice of the event of default to
the holders of the trust securities, ONEOK and the administrative trustee,
unless the event of default has been cured or waived.

   If a Junior Subordinated Indenture Event of Default occurs and is continuing
and the indenture trustee fails or the holders of not less than 25% in
principal amount of the outstanding junior subordinated debentures fail to
declare the principal of all of the junior subordinated debentures to be
immediately due and payable, the holders of at least 25% in liquidation amount
of the preferred securities then outstanding will have the right by notice in
writing to ONEOK and the indenture trustee to declare such principal
immediately due and payable. Notwithstanding the foregoing, a holder of
preferred securities may institute a legal proceeding directly against ONEOK,
without first instituting a legal proceeding against the property trustee or
any other person or entity, for enforcement of payment to that holder of
principal of or interest on the junior subordinated debentures having a
principal amount equal to the aggregate stated liquidation amount of the
preferred securities of that holder on or after the due dates specified in the
junior subordinated debentures. See "Relationship Among the Preferred
Securities, the Junior Subordinated Debentures and the Preferred Securities
Guarantee" herein and "Description of the Preferred Securities Guarantees--
Events of Default" in the accompanying prospectus.

   Unless a Junior Subordinated Indenture Event of Default shall have occurred
and be continuing, the securities trustees may be removed at any time by act of
the holder of the common securities, initially ONEOK. If a Junior Subordinated
Indenture Event of Default has occurred and is continuing, any securities
trustee may be removed at such time by act of the holders of a majority in
liquidation amount of the preferred securities, delivered to the appropriate
securities trustee, in its individual capacity and on behalf of ONEOK Capital
Trust

                                      S-22
<PAGE>

I. No resignation or removal of any securities trustee and no appointment of a
successor will be effective until the acceptance of appointment by the
successor securities trustee in accordance with the requirements of the trust
agreement.

   If a Junior Subordinated Indenture Event of Default has occurred and is
continuing, the holders of preferred securities will have a priority over the
holders of common securities upon dissolution of ONEOK Capital Trust I as
described above. See "--Liquidation Distribution Upon Dissolution."

Voting Rights

   Except as provided below and under "Description of the Preferred Securities
Guarantees--Amendments and Assignment" in the accompanying prospectus and as
otherwise required by law and the trust agreement, the holders of the preferred
securities will have no voting rights.

   If any proposed amendment to the trust agreement provides for, or the
securities trustees otherwise propose to effect, (1) any action that would
adversely affect in any material respect the powers, preferences or special
rights of the preferred securities, whether by way of amendment to the trust
agreement or otherwise, or (2) the dissolution, winding-up or termination of
ONEOK Capital Trust I, other than in accordance with the terms of the trust
agreement, then the holders of outstanding preferred securities will be
entitled to vote as a class on the amendment or proposal, and the amendment or
proposal will not be effective except with the approval of the holders of a
majority in liquidation amount of the outstanding preferred securities.

   So long as any junior subordinated debentures are held by the property
trustee, the securities trustees may not (1) direct the time, method and place
of conducting any proceeding for any remedy available to the indenture trustee,
or executing any trust or power conferred on the indenture trustee with respect
to the junior subordinated debentures, (2) waive any past default which is
waivable under the applicable provisions of the junior subordinated indenture,
(3) exercise any right to rescind or annul a declaration that the principal of
all junior subordinated debentures shall be due and payable, or (4) consent to
any amendment, modification or termination of the junior subordinated indenture
or the junior subordinated debentures, where that consent shall be required,
without, in each case, obtaining the prior approval of the holders of a
majority in liquidation amount of the outstanding preferred securities. Where,
however, a consent under the junior subordinated indenture would require the
consent of each holder of junior subordinated debentures affected thereby, no
such consent may be given by the property trustee without the prior consent of
each holder of preferred securities. The securities trustees may not revoke any
action previously authorized or approved by a vote of the holders of the
preferred securities, except pursuant to a subsequent vote of the holders. The
property trustee must notify all holders of the preferred securities of any
notice of default received from the indenture trustee. In addition to obtaining
the foregoing approvals of the holders of the preferred securities, prior to
taking any of the foregoing actions, the securities trustees must obtain an
opinion of counsel experienced in those matters to the effect that ONEOK
Capital Trust I will not be classified as other than a grantor trust for United
States federal income tax purposes on account of that action.

   Any required approval of holders of preferred securities may be given at a
separate meeting of holders of preferred securities convened for the purpose or
pursuant to written consent.

   Notwithstanding that holders of preferred securities are entitled to vote or
consent in any of the circumstances described above, any of the preferred
securities that are owned by ONEOK, the securities trustees or any affiliate of
ONEOK or any securities trustee, will, for purposes of a vote or consent, be
treated as if they were not outstanding.

                                      S-23
<PAGE>

Amendment of the Trust Agreement

   The trust agreement may be amended from time to time by ONEOK and the
securities trustees without the consent of the holders of the trust securities

  .  to cure any ambiguity, to correct or supplement any inconsistent
     provision or to make any other provisions with respect to matters or
     questions arising under the trust agreement, which must not be
     inconsistent with the other provisions of the trust agreement, provided
     that the amendment does not adversely affect in any material respect the
     interests of any holder of trust securities, or

  .  to modify, eliminate or add to any provisions of the trust agreement to
     the extent necessary to ensure that ONEOK Capital Trust I will not be
     classified as other than a grantor trust for United States federal
     income tax purposes or to ensure that ONEOK Capital Trust I will not be
     required to register as an "investment company" under the Investment
     Company Act.

   Except as provided in the following paragraph, other amendments to the
trust agreement may be made

  .  upon approval of the holders of a majority in aggregate liquidation
     amount of the trust securities then outstanding, and

  .  upon receipt by the securities trustees of an opinion of counsel to the
     effect that the amendment will not affect ONEOK Capital Trust I's status
     as a grantor trust for United States federal income tax purposes or
     ONEOK Capital Trust I's exemption from the Investment Company Act.

   Notwithstanding the foregoing, without the consent of each affected holder
of trust securities, the trust agreement may not be amended to

  .  change the amount or timing of any distribution on the trust securities
     or otherwise adversely affect the amount of any distribution required to
     be made on the trust securities as of a specified date,

  .  restrict the right of a holder of trust securities to institute suit for
     the enforcement of any payment on or after its specified due date, or

  .  change the consent required to amend the trust agreement.

Mergers, Consolidations or Amalgamations

   ONEOK Capital Trust I may not consolidate, amalgamate, merge with or into,
or be replaced by, or convey, transfer or lease its properties and assets
substantially as an entirety to any corporation or other body, except as
described below. ONEOK Capital Trust I may at the request of ONEOK, with the
consent of the administrative trustee and without the consent of the holders
of the trust securities, the property trustee or the Delaware trustee,
consolidate, amalgamate, merge with or into, or be replaced by or convey,
transfer or lease its properties and assets substantially as an entirety to a
trust organized as such under the laws of any state; provided, that:

  .  the successor entity either (1) expressly assumes all of the obligations
     of ONEOK Capital Trust I with respect to the preferred securities, or
     (2) substitutes for the preferred securities successor securities having
     substantially the same terms as the preferred securities, so long as the
     successor securities rank the same as the preferred securities rank in
     priority with respect to distributions and payments upon liquidation,
     redemption and otherwise;

  .  ONEOK expressly appoints a trustee of the successor entity possessing
     the same powers and duties as the property trustee as the holder of the
     junior subordinated debentures;

  .  the successor securities are listed or traded, or they will be listed
     upon notification of issuance, on any national securities exchange or
     other organization on which the preferred securities are then listed or
     traded;

                                     S-24
<PAGE>

  .  the transaction does not cause the preferred securities or the successor
     securities to be downgraded by any nationally recognized statistical
     rating organization;

  .  the transaction does not adversely affect the rights, preferences and
     privileges of the holders of the preferred securities or the successor
     securities in any material respect;

  .  the successor entity has a purpose substantially identical to that of
     ONEOK Capital Trust I;

  .  prior to the transaction, ONEOK has received an opinion of counsel to
     the effect that (A) the transaction does not adversely affect the
     rights, preferences and privileges of the holders of the preferred
     securities or any successor securities in any material respect, and (B)
     following the transaction neither ONEOK Capital Trust I nor the
     successor entity will be required to register as an "investment company"
     under the Investment Company Act; and

  .  ONEOK owns all the common securities of the successor entity and
     guarantees the obligations of the successor entity under the successor
     securities at least to the extent provided by the preferred securities
     guarantee.

Notwithstanding the foregoing, ONEOK Capital Trust I may not, except with the
consent of holders of all of the preferred securities, consolidate, amalgamate,
merge with or into, or be replaced by or convey, transfer or lease its
properties and assets substantially as an entirety to any other entity or
permit any other entity to consolidate, amalgamate, merge with or into, or
replace it if the transaction would cause ONEOK Capital Trust I or the
successor entity to be classified as other than a grantor trust for United
States federal income tax purposes.

   Any corporation or other body into which either the property trustee or the
Delaware trustee may be merged or converted or with which it may be
consolidated, or any corporation resulting from any merger, conversion or
consolidation or any corporation succeeding to all or substantially all the
corporate trust business of either trustee, will be the successor of that
trustee under the trust agreement, provided the resulting or surviving entity
is otherwise qualified and eligible under the trust agreement.

Payment and Paying Agent

   So long as DTC is acting as securities depositary for the preferred
securities, payments on preferred securities in global form will be made to DTC
in immediately available funds, which, in turn, is required to credit the
relevant accounts at DTC on the applicable distribution dates. If the preferred
securities are not held by DTC, payments will be made by check mailed to the
address of the holder entitled to the payment as that address appears on the
securities register maintained by            under the trust agreement. The
paying agent will initially be the property trustee. The paying agent may
resign upon 30 days' written notice to the administrative trustee, the property
trustee and ONEOK. In that event, the administrative trustee will appoint a
successor to act as paying agent.

Registrar and Transfer Agent

   The property trustee will initially act as registrar and transfer agent for
the preferred securities.

   Registration of transfers of preferred securities will be effected without
charge by or on behalf of ONEOK Capital Trust I, but upon payment of any tax or
other governmental charges which may be imposed.

   The registrar and transfer agent will not be required to register or cause
to be registered any transfer of preferred securities after they have been
called for redemption.

                                      S-25
<PAGE>

Information Concerning the Property Trustee

   The property trustee, prior to the occurrence of an event of default under
the trust agreement, undertakes to perform only the duties that are
specifically set forth in the trust agreement and, after default, is required
to exercise the same degree of care as a prudent individual would exercise in
the conduct of his or her own affairs. Subject to these provisions, the
property trustee is under no obligation to exercise any of the powers vested in
it by the trust agreement at the request of any holder of trust securities,
unless offered reasonable indemnity by the holder against the costs, expenses
and liabilities which might be incurred by the property trustee. The property
trustee is not required to expend or risk its own funds or otherwise incur any
financial liability in the performance of its duties under the trust agreement
if the property trustee reasonably believes that repayment or adequate
indemnity is not reasonably assured to it.

                  , the property trustee, also serves as indenture trustee
under the junior subordinated indenture and guarantee trustee under the
preferred securities guarantee. ONEOK and certain of its subsidiaries maintain
deposit accounts and banking relationships with                .

Governing Law

   The trust agreement and the trust securities will be governed by, and
construed in accordance with, the internal laws of the State of Delaware.

Miscellaneous

   The administrative trustee is authorized and directed to operate ONEOK
Capital Trust I so that it will not be (1) taxed as other than a grantor trust
for United States federal income tax purposes or (2) deemed to be an
"investment company" required to be registered under the Investment Company
Act, and so that the junior subordinated debentures will be treated as
indebtedness of ONEOK for United States federal income tax purposes. In this
connection, the administrative trustee and ONEOK are authorized to take any
action, not inconsistent with applicable law, ONEOK Capital Trust I's
certificate of trust or the trust agreement, that the administrative trustee
and ONEOK determine in their discretion to be necessary or desirable for those
purposes, as long as that action does not materially and adversely affect the
interests of the holders of the preferred securities.

               DESCRIPTION OF THE JUNIOR SUBORDINATED DEBENTURES

   Set forth below is a description of the specific terms of the junior
subordinated debentures. This description supplements, and should be read
together with, the description of the general terms and provisions of the
junior subordinated debentures set forth in the accompanying prospectus under
the caption "Description of the Junior Subordinated Debentures." The following
description does not purport to be complete and is subject to, and is qualified
in its entirety by reference to, the description in the accompanying prospectus
and the junior subordinated indenture.

General

   The junior subordinated debentures will be issued under the junior
subordinated indenture. The junior subordinated debentures will be limited in
aggregate principal amount to $            , which is the approximate aggregate
liquidation amount of the trust securities.

                                      S-26
<PAGE>

   The entire principal amount of the junior subordinated debentures will
mature and become due and payable, together with any accrued and unpaid
interest thereon, including Additional Interest (see "Description of the Junior
Subordinated Debentures--Additional Interest" in the accompanying prospectus),
if any, on          ,   . The junior subordinated debentures are not subject to
any sinking fund provision.

   The terms of the junior subordinated debentures correspond to those of the
preferred securities, as described herein.

Optional Redemption

   ONEOK will have the right to redeem the junior subordinated debentures, in
whole or in part, without premium, from time to time, on or after          ,
  , or at any time in whole, but not in part, upon the occurrence of a Special
Event as described under "Description of the Preferred Securities--Special
Event Redemption or Distribution" upon not less than 30 or more than 60 days'
notice, at a redemption price equal to 100% of the principal amount to be
redeemed plus any accrued and unpaid interest, including Additional Interest,
if any, to the redemption date.

Interest

   Each junior subordinated debenture will bear interest at the annual rate of
     % from their date of original issue, payable quarterly in arrears on
     ,      ,       and       of each year commencing          , 1999, to the
person in whose name the junior subordinated debenture is registered on the
business day immediately prior to the payment date, or, if the junior
subordinated debentures are not in book-entry only form, the fifteenth calendar
day preceding the payment date. The amount of interest payable will be computed
on the basis of a 360-day year of twelve 30-day months. If any date on which
interest is payable on the junior subordinated debentures is not a business
day, then payment of the interest payable on that date will be made on the next
succeeding day which is a business day without any interest or other payment
because of the delay. If, however, the business day is in the next succeeding
calendar year, the payment will be made on the immediately preceding business
day.

Option to Extend Interest Payment Period

   So long as no Junior Subordinated Indenture Event of Default has occurred
and is continuing, ONEOK will have the right at any time, and from time to
time, to defer payments of interest on the junior subordinated debentures by
extending the interest payment period for up to 20 consecutive quarters, but
not beyond the stated maturity date. At the end of an extension period, ONEOK
will pay all interest then accrued and unpaid, including any Additional
Interest thereon at the annual rate of      % to the extent permitted by
applicable law. However, during any extension period, subject to the exceptions
described under "Description of the Junior Subordinated Debentures--Covenants"
in the accompanying prospectus, ONEOK may not

  .  declare or pay any dividend or distribution on, or redeem, purchase,
     acquire or make a liquidation payment with respect to, any of its
     capital stock, or

  .  make any payment of interest, principal or premium, if any, on or repay,
     repurchase or redeem any debt securities issued by it which rank equally
     with or junior to the junior subordinated debentures or make any
     guarantee payments on any guarantee by it of debt securities of any of
     its subsidiaries if the guarantee is equal to or junior in interest to
     the junior subordinated debentures.

   Prior to the termination of any extension period, ONEOK may further defer
payments of interest by extending the interest payment period, provided that
the extension period, together with all previous and further extensions of the
extension period, may not exceed 20 consecutive quarters or extend beyond the
stated maturity date. Upon the termination of any extension period and the
payment of all amounts then due, ONEOK may defer payments of interest in a new
extension period, subject to the above requirements. ONEOK has no present
intention of exercising its rights to defer payments of interest by extending
the interest payment period on the junior subordinated debentures. See
"Taxation--Interest and Original Issue Discount."

                                      S-27
<PAGE>

   ONEOK must give the holder or holders of the junior subordinated debentures
and the indenture trustee notice of its election to begin or extend an
extension period at least one business day prior to the earlier of

  .  the next succeeding date on which distributions on the preferred
     securities would be payable but for the deferral, or

  .  the date the administrative trustee is required to give notice to any
     securities exchange or other applicable self-regulatory organization or
     to the holders of the preferred securities of the record date or the
     date the distributions are payable, but in any event not less than one
     business day prior to the record date.

Payment of Additional Sums

   If a Tax Event has occurred and is continuing and ONEOK does not elect to
redeem the junior subordinated debentures as described under "--Optional
Redemption" above, or liquidate ONEOK Capital Trust I, ONEOK will be required
to pay additional amounts, if necessary, to the holders of the junior
subordinated debentures so that, notwithstanding any additional taxes, duties
or charges imposed on ONEOK Capital Trust I because of the Tax Event, ONEOK
Capital Trust I will have sufficient funds to pay the full amount of
distributions due on the preferred securities then outstanding.

Book-Entry and Issuance

   If distributed to holders of trust securities in connection with the
voluntary or involuntary dissolution, winding-up or liquidation of ONEOK
Capital Trust I, the junior subordinated debentures are expected to be issued
in the form of one or more global certificates registered in the name of the
securities depositary or its nominee. In that event, the procedures applicable
to the transfer and payment of the junior subordinated debentures, notices and
the like are expected to be substantially similar to those described with
respect to the preferred securities in "Description of the Preferred
Securities--Book-Entry Only Issuance--The Depository Trust Company."

RELATIONSHIP AMONG THE PREFERRED SECURITIES, THE JUNIOR SUBORDINATED DEBENTURES
                     AND THE PREFERRED SECURITIES GUARANTEE

   As long as payments of interest and other payments are made when due on the
junior subordinated debentures those payments will be sufficient to cover
distributions and payments due on the trust securities primarily because

  .  the aggregate principal amount of junior subordinated debentures will be
     equal to the sum of the aggregate stated liquidation amount of the trust
     securities;

  .  the interest rate and interest and other payment dates on the junior
     subordinated debentures will match the distribution rate and
     distribution and other payment dates for the preferred securities;

  .  ONEOK will pay all costs and expenses of ONEOK Capital Trust I pursuant
     to the agreement as to expenses and liabilities; and

  .  the trust agreement provides that the securities trustees may not cause
     or permit ONEOK Capital Trust I to, among other things, engage in any
     activity that is not consistent with the purposes of ONEOK Capital Trust
     I.

   Payments of distributions, to the extent funds therefor are legally and
immediately available, and other payments due on the preferred securities, to
the extent funds therefor are legally and immediately available, are guaranteed
by ONEOK as described under "Description of the Preferred Securities
Guarantees" in the

                                      S-28
<PAGE>

accompanying prospectus. If ONEOK does not make interest payments on the junior
subordinated debentures, it is not expected that ONEOK Capital Trust I will
have sufficient funds to pay distributions on the preferred securities. The
preferred securities guarantee is a guarantee from the time of its issuance,
but does not apply to any payment of distributions unless and until ONEOK
Capital Trust I has sufficient funds legally and immediately available for the
payment of those distributions.

   If a Junior Subordinated Indenture Event of Default occurs and is continuing
and the indenture trustee fails or the holders of not less than 25% in
principal amount of the outstanding junior subordinated debentures fail to
declare the principal of all of the junior subordinated debentures to be
immediately due and payable, the holders of at least 25% in liquidation amount
of the preferred securities then outstanding will have the right by notice in
writing to ONEOK and the indenture trustee to declare the principal of the
junior subordinated debentures immediately due and payable. Notwithstanding the
foregoing, a holder of preferred securities may institute a legal proceeding
directly against ONEOK, without first instituting a legal proceeding against
the property trustee or any other person or entity, for enforcement of payment
to that holder of principal of or interest on the junior subordinated
debentures having a principal amount equal to the aggregate stated liquidation
amount of the preferred securities of that holder on or after the due dates
specified in the junior subordinated debentures.

   If ONEOK fails to make payments under the preferred securities guarantee,
the preferred securities guarantee provides a mechanism whereby the holders of
the preferred securities may direct the guarantee trustee to enforce its rights
thereunder. In addition, any holder of preferred securities may institute a
legal proceeding directly against ONEOK to enforce its rights under the
preferred securities guarantee without first instituting a legal proceeding
against the guarantee trustee or any other person or entity.

   The preferred securities guarantee, the junior subordinated indenture, the
junior subordinated debentures, the trust agreement and the agreement as to
expenses and liabilities, as described above, constitute a full and
unconditional guarantee by ONEOK of the payments due on the preferred
securities.

   Upon any voluntary or involuntary dissolution, winding-up or termination of
ONEOK Capital Trust I, unless the junior subordinated debentures are
distributed in connection therewith, the holders of preferred securities will
be entitled to receive, out of assets legally available for distribution to
holders, the liquidation distribution in cash. See "Description of the
Preferred Securities--Liquidation Distribution Upon Dissolution." Upon any
voluntary or involuntary liquidation or bankruptcy of ONEOK, the property
trustee, as holder of the junior subordinated debentures, would be a
subordinated creditor of ONEOK, subordinated in right of payment to all Senior
Debt (as defined in the accompanying prospectus under the caption "Description
of the Junior Subordinated Debentures--Subordination"), but entitled to receive
payment in full of principal and interest before any stockholders of ONEOK
receive payments or distributions. Because ONEOK is guarantor under the
preferred securities guarantee and has agreed to pay for all costs, expenses
and liabilities of ONEOK Capital Trust I (other than ONEOK Capital Trust I's
obligations to holders of the preferred securities) pursuant to the agreement
as to expenses and liabilities, the positions of a holder of preferred
securities and a holder of junior subordinated debentures relative to other
creditors and to stockholders of ONEOK in the event of liquidation or
bankruptcy of ONEOK would be substantially the same.

   A default or event of default under any Senior Debt would not constitute a
default or event of default under the junior subordinated indenture. However,
in the event of payment defaults under, or acceleration of, Senior Debt, the
subordination provisions of the junior subordinated debentures provide that no
payments may be made on the junior subordinated debentures until that Senior
Debt has been paid in full or any payment default thereunder has been cured or
waived. Failure to make required payments on the junior subordinated debentures
would constitute an event of default under the junior subordinated indenture
except that failure to make interest payments on the junior subordinated
debentures will not be an event of default during an extension period.


                                      S-29
<PAGE>

                                    TAXATION

   In the opinion of Gable & Gotwals, counsel to ONEOK and ONEOK Capital Trust
I ("Tax Counsel"), the following are the material United States federal income
tax consequences of the ownership and disposition of preferred securities.
Please note that the opinion of Tax Counsel is not binding on the Internal
Revenue Service. Unless otherwise stated, this summary deals only with
preferred securities held as capital assets by holders who acquire the
preferred securities upon original issuance at their original offering price
("Initial Holders"). It does not deal with special classes of holders, such as
dealers in securities or currencies, financial institutions, life insurance
companies, tax-exempt organizations, individual retirement and tax deferred
accounts, persons holding preferred securities as part of a straddle or as part
of a hedging or conversion transaction, or persons whose functional currency is
not the United States dollar. This summary is based on the Internal Revenue
Code of 1986, Treasury Regulations thereunder and administrative and judicial
interpretations of the Code as of the date of this prospectus supplement, all
of which are subject to change, possibly on a retroactive basis.

   Investors are advised to consult their tax advisors as to the United States
federal income tax consequences of the ownership and disposition of preferred
securities in light of their particular circumstances, as well as the effect of
any state, local or other tax laws.

Classification of ONEOK Capital Trust I as a Grantor Trust

   In the opinion of Tax Counsel, under current law and assuming full
compliance with the terms of the trust agreement, ONEOK Capital Trust I will be
classified for United States federal income tax purposes as a grantor trust and
not as an association taxable as a corporation. Accordingly, each holder of
preferred securities will be considered the owner of a pro rata portion of the
junior subordinated debentures held by ONEOK Capital Trust I. Accordingly, each
securityholder will be required to include in gross income its pro rata share
of the interest income, including original issue discount, if any, paid or
accrued with respect to the junior subordinated debentures, whether or not cash
is actually distributed to the securityholder.

Classification of the Junior Subordinated Debentures as Indebtedness

   In the opinion of Tax Counsel, under current law and assuming full
compliance with the junior subordinated indenture, the junior subordinated
debentures will be classified for United States federal income tax purposes as
indebtedness of ONEOK.

Interest and Original Issue Discount

   If an extension period occurs, the junior subordinated debentures would be
considered to have original issue discount at all times after the beginning of
the first extension period, including after the termination of the extension
period. In addition, ONEOK's option to defer the payment of interest on the
junior subordinated debentures during an extension period might cause the
junior subordinated debentures to be considered initially issued with original
issue discount. ONEOK believes, and will take the position, that this latter
result will not arise because the likelihood of the occurrence of an extension
period is very remote. The applicable United States Treasury Regulations
provide that when there is only a "remote" likelihood that a contingency such
as an extension period will occur, a debt instrument will not be considered
initially issued with original issue discount. Assuming that the likelihood of
an extension period is in fact remote, Tax Counsel believes that this position
is correct. However, there is no authority directly on point interpreting the
applicable Treasury Regulations, and the Internal Revenue Service could take a
contrary position.

   If the original issue discount rules apply to the junior subordinated
debentures, either following the occurrence of an extension period or
initially, each securityholder, whether on the cash or accrual method of
accounting, will be required to accrue its pro rata share of original issue
discount into income in accordance with a constant yield method based on the
compounding of interest. As a result, income will be required to be reported by
securityholders before the receipt of cash attributable to such income, and, in
particular, income

                                      S-30
<PAGE>

will be reported during an extension period as it accrues even though no cash
distributions are being made. If the original issue discount rules apply for a
period during which full cash distributions are currently being made, the sum
of the daily accruals of income for a quarterly period for a securityholder
that purchased the preferred securities at a price equal to their liquidation
value will equal the cash distribution received by the securityholder for such
quarter, assuming no disposition prior to the record date for that
distribution.

   If the original issue discount rules become applicable, actual distributions
of stated interest will not separately be reported as income. Also in that
case, a securityholder's tax basis for the junior subordinated debentures will
be increased by original issue discount accrued into income, and decreased by
cash distributions of interest. If the original issue discount rules do not
apply, stated interest will be includible in a securityholder's gross income as
ordinary interest income at the time it is paid or accrued in accordance with
the securityholder's regular method of tax accounting.

   Whether or not the original issue discount rules apply, no portion of the
amounts received on the preferred securities will be eligible for the corporate
dividends received deduction.

Distribution of Junior Subordinated Debentures to Holders of Preferred
Securities

   Under current law, a distribution by ONEOK Capital Trust I of the junior
subordinated debentures as described under the captions "Description of the
Preferred Securities--Exchange of Junior Subordinated Debentures for Preferred
Securities" and "--Liquidation Distribution Upon Dissolution" will be non-
taxable and will result in the securityholder receiving directly its pro rata
share of the junior subordinated debentures previously held indirectly through
ONEOK Capital Trust I, with a holding period and tax basis equal to the holding
period and adjusted tax basis that securityholder was considered to have had in
its pro rata share of the underlying junior subordinated debentures immediately
prior to such distribution. If, however, the Special Event giving rise to the
distribution is a Tax Event which results in ONEOK Capital Trust I being
treated as an association taxable as a corporation, the distribution would
constitute a taxable event to securityholders.

Market Discount and Bond Premium

   Securityholders other than Initial Holders may be considered to have
acquired their pro rata interest in the junior subordinated debentures with
market discount, acquisition premium or amortizable bond premium. Those
securityholders are advised to consult their tax advisors as to the income tax
consequences of the acquisition, ownership and disposition of the preferred
securities.

Disposition of the Preferred Securities by Holders

   Upon a sale, exchange or other disposition of the preferred securities,
including a distribution of cash in redemption of a securityholder's preferred
securities upon redemption or repayment of the underlying junior subordinated
debentures (other than a distribution of junior subordinated debentures) a
securityholder will be considered to have disposed of all or part of its pro
rata share of the junior subordinated debentures. The securityholder will
recognize gain or loss equal to the difference between the amount realized,
other than amounts attributable to accrued but unpaid interest that is not
treated as original issue discount, and the securityholder's adjusted tax basis
in its pro rata share of the underlying junior subordinated debentures deemed
disposed of in the transaction. A securityholder's adjusted tax basis in the
preferred securities generally will be the initial purchase price increased by
original issue discount previously includible in its gross income to the date
of disposition and decreased by payments, other than payments of stated
interest that are not treated as original issue discount, received on the
preferred securities. Gain or loss on any such sale, exchange or disposition
will be capital gain or loss, except to the extent of any accrued interest or
market discount not previously included in income. The gain or loss will be
long-term capital gain or loss if the preferred securities have been held for
more than one year. Long-term capital gain of a non-corporate securityholder is
generally subject to a maximum United States federal income tax rate of 20%.
See "Market Discount and Bond Premium" above concerning market discount.

                                      S-31
<PAGE>

   If ONEOK defers any interest payment on the junior subordinated debentures,
the preferred securities may trade at a price that does not fully reflect the
value of accrued but unpaid interest on the junior subordinated debentures. A
securityholder that sells its preferred securities between record dates for
payments of distributions will be required to include accrued but unpaid
interest on the junior subordinated debentures through the date of disposition
as ordinary income and to add the amount of the accrued but unpaid interest to
its adjusted tax basis in the preferred securities. To the extent the selling
price is less than the securityholder's adjusted tax basis, the securityholder
will recognize a capital loss. Subject to certain limited exceptions, a
securityholder cannot deduct capital losses from ordinary income for United
States federal income tax purposes.

United States Alien Holders

   For purposes of this discussion, a "United States Alien Holder" is any
individual, corporation, partnership, estate or trust that is, as to the United
States, a non-resident alien individual or a foreign corporation, partnership,
estate or trust.

   Under present United States federal income tax law:

       (1)  payments by ONEOK Capital Trust I or any of its paying agents to
  any holder of a preferred security who or which is a United States Alien
  Holder will not be subject to United States federal income or withholding
  tax, if

    .  the beneficial owner of the preferred security does not actually or
       constructively own 10% or more of the total combined voting power of
       all classes of stock of ONEOK entitled to vote;

    .  the beneficial owner of the preferred security is not a controlled
       foreign corporation that is related to ONEOK through stock
       ownership;

    .  either (A) the beneficial owner of the preferred security certifies
       to ONEOK Capital Trust I or its agent, under penalties of perjury,
       that it is not a United States person and provides its name and
       address or (B) a securities clearing organization, bank or other
       financial institution that holds customers' securities in the
       ordinary course of its trade or business (a "Financial Institution")
       and holds the preferred security in such capacity certifies to ONEOK
       Capital Trust I or its agent, under penalties of perjury, that such
       statement has been received from the beneficial owner by it or by a
       Financial Institution between it and the beneficial owner and
       furnishes ONEOK Capital Trust I or its agent with a copy of such
       statement; and

    .  such payments are not effectively connected with the conduct by the
       United States Alien Holder of a trade or business in the United
       States.

       (2)  A United States Alien Holder of a preferred security will not be
  subject to United States federal income or withholding tax on any gain
  realized upon the sale or other disposition of a preferred security unless

    .  the United States Alien Holder is an individual who is present in
       the United States for 183 days or more in the taxable year of
       disposition, and other conditions apply, or

    .  the gain is effectively connected with the conduct by the United
       States Alien Holder of a trade or business in the United States.

   Under recently finalized Treasury Regulations, the certification requirement
referred to in the third bullet point of (1) above may also be satisfied with
other documentary evidence for payments made after December 31, 2000 with
respect to an offshore account or through certain foreign intermediaries.

                                      S-32
<PAGE>

   Investors who are or may be considered to be United States Alien Holders are
advised to consult their tax advisors as to United States federal income tax
consequences of the acquisition, ownership and disposition of the preferred
securities, the exact application and effect of federal income tax rules and
particular actions necessary to comply with applicable rules.

Information Reporting to Holders

   ONEOK Capital Trust I will report the interest paid or the original issue
discount that accrued during the calendar year on the junior subordinated
debentures, and any gross proceeds received by ONEOK Capital Trust I from the
retirement or redemption of the junior subordinated debentures, annually to the
holders of record of the preferred securities and the Internal Revenue Service.
ONEOK Capital Trust I currently intends to deliver reports to holders of record
prior to January 31 following each calendar year.

Backup Withholding

   Payments made to a securityholder on, and proceeds from the sale of,
preferred securities may be subject to a "backup" federal withholding tax of
31% if the securityholder does not comply with various requirements concerning
the furnishing of a taxpayer identification number and reporting of interest or
dividend income. Any withheld amounts will generally be allowed as a credit
against the securityholder's United States federal income tax, provided the
required information is timely filed with the Internal Revenue Service.

Possible Tax Law Changes

   From time to time, the Clinton Administration has proposed tax law changes
that would have, among other things, denied interest deductions to a corporate
issuer of a debt instrument having a term exceeding 15 years if that debt
instrument was not reflected as indebtedness on the issuer's consolidated
balance sheet. Other proposed tax law changes would have denied interest
deductions if the debt instrument had a term exceeding 20 years. These propsoed
changes have not been enacted into law. No similar proposal was made in the
Administration's budget proposal released on February 1, 1999. Although it is
impossible to predict the effect of future proposals, the prior proposals
mentioned, if enacted into law, would not have applied to securities with
characteristics similar to the junior subordinated debentures that were already
issued and outstanding at the time that legislation was proposed. However, if a
future proposal of this nature were to become effective in a form applicable to
already issued and outstanding securities, ONEOK could be precluded from
deducting interest on the junior subordinated debentures. That might in turn
give rise to a Tax Event that, if ONEOK were to exercise its optional right to
redeem the junior subordinated debentures, would result in a mandatory
redemption of the preferred securities, as described under "Description of the
Preferred Securities--Redemption."

                                      S-33
<PAGE>

                                  UNDERWRITING

   Subject to the terms and conditions set forth in an underwriting agreement
dated the date of this prospectus supplement, ONEOK and ONEOK Capital Trust I
have agreed that ONEOK Capital Trust I will sell to each of the underwriters
named below, and each of the underwriters named below, for whom PaineWebber
Incorporated is acting as representative, has severally agreed to purchase from
ONEOK Capital Trust I, the number of preferred securities set forth opposite
its name below.

<TABLE>
<CAPTION>
                                                                 Number of
      Underwriters                                          Preferred Securities
      ------------                                          --------------------
      <S>                                                   <C>
      PaineWebber Incorporated.............................
                                                                   -----
          Total............................................
                                                                   =====
</TABLE>

   In the underwriting agreement, the several underwriters have agreed, subject
to the terms and conditions set forth in the underwriting agreement, to
purchase all the preferred securities offered by this prospectus supplement if
any preferred securities are purchased by the underwriters. In the event of
default by an underwriter, the underwriting agreement provides that, in certain
circumstances, the purchase commitment of the nondefaulting underwriters may be
increased or the underwriting agreement may be terminated.

   ONEOK has been advised by the representative that the underwriters propose
initially to offer the preferred securities to the public at the public
offering price set forth on the cover page of this prospectus supplement, and
to certain dealers at such price less a concession not in excess of $   per
preferred security. The underwriters may allow, and such dealers may reallow, a
concession not in excess of $   per preferred security to certain brokers and
dealers. After the initial public offering, the public offering price and such
concessions may be changed. ONEOK expects the preferred securities will be
ready for delivery in book-entry form only through The Depository Trust Company
on or about        , 1999.

   ONEOK estimates that it will incur $     in offering expenses related to
registration and filing fees, printing and engraving expenses, rating agency
fees, and professional services fees in connection with this offering.

   In view of the fact that the proceeds of the sale of the preferred
securities will be used to purchase the junior subordinated debentures of
ONEOK, the underwriting agreement provides that ONEOK will pay as underwriters'
compensation for the underwriters' purchasing the preferred securities and
arranging the investment of those proceeds in junior subordinated debentures
$    per $25 liquidation amount of preferred securities, or $             in
the aggregate, for the accounts of the several underwriters.

   During a period of 30 days from the date of this prospectus supplement,
neither ONEOK Capital Trust I nor ONEOK will, without the prior written consent
of the representative, directly or indirectly, sell, offer to sell, grant any
option for the sale of, or otherwise dispose of, any preferred securities, any
security convertible into or exchangeable into or exercisable for preferred
securities or junior subordinated debentures or any debt securities
substantially similar to the junior subordinated debentures or equity
securities substantially similar to the preferred securities except for the
junior subordinated debentures and the preferred securities offered by this
prospectus supplement.

   Until the distribution of the preferred securities is completed, rules of
the Securities and Exchange Commission may limit the ability of the
underwriters and certain selling group members to bid for and purchase the
preferred securities. As an exception to these rules, the representative is
permitted to engage in

                                      S-34
<PAGE>

certain transactions that stabilize the price of the preferred securities. Such
transactions consist of bids or purchases for the purpose of pegging, fixing or
maintaining the price of the preferred securities.

   If the underwriters create a short position in the preferred securities in
connection with the offering, i.e., if they sell more shares of preferred
securities than are set forth on the cover page of this prospectus supplement,
the representative may reduce that short position by purchasing preferred
securities in the open market.

   The representative may also impose a penalty bid on certain underwriters and
selling group members. This means that if the representative purchases shares
of preferred securities in the open market to reduce the underwriters' short
position or to stabilize the price of the preferred securities, the
representative may reclaim the amount of the selling concession from the
underwriters and selling group members who sold those shares as part of the
offering.

   In general, purchases of a security for the purpose of stabilization or to
reduce a short position could cause the price of the security to be higher than
it might be in the absence of such purchases. The imposition of a penalty bid
might also have an effect on the price of a security to the extent that it were
to discourage resales of the security.

   None of ONEOK, ONEOK Capital Trust I or any of the underwriters makes any
representation or prediction as to the direction or magnitude of any effect
that the transactions described above may have on the price of the preferred
securities. In addition, none of ONEOK, ONEOK Capital Trust I or any of the
underwriters makes any representation that the representative will engage in
such transactions or that such transactions, once commenced, will not be
discontinued without notice.

   Application will be made to list the preferred securities on the New York
Stock Exchange. The New York Stock Exchange symbol for the preferred securities
is expected to be "     ." If such listing is approved, trading of the
preferred securities on the New York Stock Exchange is expected to commence
within a 30-day period after the date of this prospectus supplement.
PaineWebber Incorporated has advised ONEOK Capital Trust I that it intends to
make a market in the preferred securities. PaineWebber Incorporated will have
no obligation to make a market in the preferred securities, however, and may
cease market making activities, if commenced, at any time.

   Prior to this offering, there has been no public market for the preferred
securities. In order to meet one of the requirements for listing the preferred
securities on the NYSE, the underwriters will represent that, at the time of
the consummation of the offering of the preferred securities, there will be at
least 400 holders of preferred securities.

   ONEOK has agreed to indemnify the underwriters against certain liabilities,
including liabilities under the Securities Act of 1933, or contribute to
payments which the underwriters may be required to make in respect of the
Securities Act of 1933.

   Certain of the underwriters or their affiliates have provided from time to
time, and expect to provide in the future, investment or commercial banking
services to ONEOK and its affiliates, for which they have received or will
receive customary fees and commissions.

                                 LEGAL MATTERS

   Matters of Delaware law relating to the validity of the preferred securities
will be passed upon on behalf of ONEOK Capital Trust I by Richards, Layton &
Finger, P.A., Wilmington, Delaware, special Delaware counsel to ONEOK Capital
Trust I. The validity of the preferred securities and the preferred securities
guarantee and matters relating thereto will be passed upon on behalf of ONEOK
by Gable & Gotwals, Tulsa, Oklahoma. Gable & Gotwals will pass upon matters
relating to United States federal income tax considerations.

                                      S-35
<PAGE>

Various legal matters will be passed upon for the underwriters by Jones, Day,
Reavis & Pogue, Chicago, Illinois. Jones, Day, Reavis & Pogue will rely on
Gable & Gotwals as to matters of Oklahoma law. Jones, Day, Reavis & Pogue from
time to time acts as counsel to ONEOK.

                                    EXPERTS

   The consolidated financial statements of ONEOK and its subsidiaries as of
August 31, 1998 and 1997, and for each of the years in the three-year period
ended August 31, 1998 have been incorporated by reference herein in reliance
upon the report of KPMG LLP, independent certified public accountants,
incorporated by reference herein, and upon the authority of said firm as
experts in accounting and auditing.

   The consolidated financial statements of Southwest Gas and its subsidiaries
as of December 31, 1998 and 1997, and for each of the years in the three-year
period ended December 31, 1998, incorporated by reference in ONEOK's current
report on Form 8-K dated April 15, 1999, incorporated by reference herein, have
been audited by Arthur Andersen LLP, independent public accountants, as
indicated in their report with respect thereto, and which are incorporated by
reference herein in reliance upon the authority of said firm as experts in
giving said report.

                                      S-36
<PAGE>

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+The information in this prospectus is not complete and may be changed. We may +
+not sell these securities until the registration statement filed with the     +
+Securities and Exchange Commission is effective. This prospectus is not an    +
+offer to sell these securities and it is not soliciting an offer to buy these +
+securities in any state where the offer or sale is not permitted.             +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                   SUBJECT TO COMPLETION, DATED JULY 13, 1999

Prospectus

                                  ONEOK, Inc.
                         Junior Subordinated Debentures

                             ONEOK Capital Trust I
                             ONEOK Capital Trust II
          Preferred Securities Fully and Unconditionally Guaranteed by
                                  ONEOK, Inc.

  By this prospectus, we may offer up to $            of securities.

  ONEOK, Inc. may offer, from time to time, junior subordinated debentures in
one or more series, and in amounts, at prices and on terms to be determined at
or prior to the time of any offering. The junior subordinated debentures will
be unsecured obligations of ONEOK.

  Each of ONEOK Capital Trust I and ONEOK Capital Trust II may offer and sell,
from time to time, preferred securities representing preferred ownership
interests in the assets of a ONEOK Trust. The payment of periodic cash
distributions and payments on liquidation of a ONEOK Trust and on redemption of
preferred securities of a ONEOK Trust will be guaranteed by ONEOK on a
subordinated basis and as described in this prospectus under "Description of
the Preferred Securities Guarantees." The guarantees cover payments only if and
to the extent that a ONEOK Trust has funds available for payment.

  Each ONEOK Trust will use all proceeds received from the sale of its trust
securities to purchase junior subordinated debentures from ONEOK. Since the
sole asset of each ONEOK Trust will be the junior subordinated debentures of
ONEOK issued to it, these trusts will not have funds available for payment if
ONEOK fails to make a corresponding payment under the junior subordinated
debentures.

  We will provide specific terms of the junior subordinated debentures of ONEOK
and the preferred securities of any ONEOK Trust in supplements to this
prospectus. The prospectus supplement may also add, update or change
information contained in this prospectus. You should read this prospectus and
any prospectus supplement carefully before you invest.

                                 ------------

  Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
adequacy or accuracy of this prospectus. Any representation to the contrary is
a criminal offense.

                                 ------------

  This prospectus may not be used to consummate sales of offered securities
unless accompanied by a prospectus supplement.

                                 ------------

                The date of this prospectus is          , 1999.
<PAGE>

                      WHERE YOU CAN FIND MORE INFORMATION

   We file annual, quarterly and special reports, proxy statements and other
information with the Securities and Exchange Commission. Our filings are
available to the public over the Internet at the Securities and Exchange
Commission's web site at http://www.sec.gov. You may also read and copy any
document we file at the Securities and Exchange Commission's public reference
rooms at 450 Fifth Street, NW, Washington, D.C. 20549; Seven World Trade
Center, New York, New York 10048; and 500 West Madison Street, Suite 1400,
Chicago, Illinois 60661. Please call the Securities and Exchange Commission at
1-800-SEC-0330 for further information on the public reference rooms.

   This prospectus is a part of the registration statement on Form S-3 and the
related amendments and exhibits filed with the Securities and Exchange
Commission. This prospectus does not contain all of the information in the
registration statement. Please refer to the registration statement and its
exhibits for further information regarding ONEOK, the ONEOK Trusts and the
offered securities.

   We have not included or incorporated by reference separate financial
statements of any of the ONEOK Trusts. ONEOK and the ONEOK Trusts do not
consider that those financial statements would be material to holders of the
preferred securities because:

  .  all voting securities of each ONEOK Trust will be owned directly or
     indirectly by ONEOK;

  .  each ONEOK Trust is a special purpose entity, has no operating history,
     has no independent operations and is not engaged in, and does not
     propose to engage in, any activity other than issuing trust securities
     representing undivided beneficial interests in the assets of that ONEOK
     Trust and investing the proceeds in junior subordinated debt securities
     issued by ONEOK; and

  .  the obligations of each ONEOK Trust under the preferred securities of
     that ONEOK Trust will be fully and unconditionally guaranteed by ONEOK
     as described in this prospectus.

   Each holder of preferred securities of a ONEOK Trust will be furnished
annually with unaudited financial statements of that ONEOK Trust as soon as
available after the end of that ONEOK Trust's fiscal year.

                      DOCUMENTS INCORPORATED BY REFERENCE

   The Securities and Exchange Commission allows us to "incorporate by
reference" the information we file with it, which means that we can disclose
important information to you by referring you to those documents. The
information incorporated by reference is an important part of this prospectus,
and information that we file later with the Securities and Exchange Commission
will automatically update and supersede this information. We incorporate by
reference the documents of ONEOK listed below and any future filings made with
the Securities and Exchange Commission under Section 13(a), 13(c), 14, or 15(d)
of the Securities Exchange Act of 1934, until we sell all of the securities.

  .  Annual Report on Form 10-K for the year ended August 31, 1998;

  .  Quarterly Reports on Form 10-Q for the quarters ended November 30, 1998,
     February 28, 1999 and May 31, 1999; and

  .  Current Reports on Form 8-K, dated September 24, 1998 (as amended on
     October 2, 1998), October 21, 1998, December 16, 1998, December 16,
     1998, January 25, 1999 (as amended on January 26, 1999), January 25,
     1999, February 8, 1999, February 16, 1999, February 23, 1999, February
     24, 1999, February 24, 1999, February 26, 1999, March 5, 1999, March 19,
     1999, April 15, 1999 (as amended on April 29, 1999), April 19, 1999,
     April 22, 1999, April 26, 1999, May 3, 1999, May 13, 1999, June 22, 1999
     and July 12, 1999.

                                       2
<PAGE>

   You may request a copy of these filings at no cost, by writing or
telephoning us at the following address: ONEOK, Inc., 100 West Fifth Street,
Tulsa, Oklahoma 74103, telephone (918) 588-7000, Attention: Treasurer.

   You should rely only on the information contained or incorporated by
reference in this prospectus or any prospectus supplement. We have not
authorized any other person to provide you with different information. We are
not making an offer of these securities in any jurisdiction where the offer is
not permitted. You should assume that the information appearing in this
prospectus or any prospectus supplement, as well as information we previously
filed with the Securities and Exchange Commission and incorporated by
reference, is accurate as of the date on the front of those documents only.

                                     ONEOK

   ONEOK and its subsidiaries engage in several aspects of the energy business.
ONEOK purchases, gathers, compresses, transports and stores natural gas for
distribution to consumers. ONEOK transports gas for others and leases pipeline
capacity to others for use in transporting gas. ONEOK drills for and produces
gas and oil, extracts and sells natural gas liquids, and engages in the gas
marketing business. In addition, ONEOK leases and operates a headquarters
office building (leasing space it does not use to others) and owns and operates
a related parking facility. As a regulated natural gas utility, ONEOK
distributes natural gas to approximately 1.4 million customers in the states of
Oklahoma and Kansas.

   ONEOK has agreed to acquire Southwest Gas Corporation by merger for cash of
approximately $917 million. ONEOK will be the survivor of the proposed merger
transaction. Southwest Gas is a regulated natural gas utility that distributes
natural gas to      customers in the states of Nevada, Arizona and California.
The proposed merger is subject to customary conditions, including approval by
the shareholders of Southwest Gas and the receipt of governmental and other
authorizations, and is expected to close later in 1999. ONEOK has received the
requisite approvals from the Public Service Commission of Nevada and expects to
receive the requisite approvals from the States of Arizona and California by
the end of the third quarter of 1999. It is possible that regulatory approvals
that are obtained will contain conditions or limitations that will adversely
affect the results of operations of the combined company. Unaudited pro forma
combined condensed financial data giving effect to the proposed merger are
included in ONEOK's current report on Form 8-K dated July 12, 1999, which is
incorporated herein by reference.

   ONEOK's principal executive offices are located at 100 West Fifth Street,
Tulsa, Oklahoma 74103, and its telephone number is (918) 588-7000.

   For purposes of the foregoing description, all references to ONEOK refer
collectively to ONEOK, Inc. and its operating subsidiaries, unless the context
otherwise requires.

                                THE ONEOK TRUSTS

   Each ONEOK Trust is a statutory business trust created under Delaware law
pursuant to the filing of a certificate of trust with the Secretary of State of
the State of Delaware. Each ONEOK Trust's business is defined in a trust
agreement, executed by ONEOK, as depositor, the Delaware trustee and property
trustee thereunder. Each trust agreement will be amended and restated in its
entirety on the date that the ONEOK Trust issues preferred securities.
References to each trust agreement in this prospectus are to each amended and
restated trust agreement. Each trust agreement will be qualified under the
Trust Indenture Act of 1939. Each ONEOK Trust exists for the exclusive purposes
of (1) issuing the preferred securities and the common securities (collectively
referred to in this prospectus as the trust securities) representing undivided,
beneficial interests in the assets the ONEOK Trust, (2) investing the gross
proceeds of the trust securities in the junior subordinated debentures and (3)
engaging in only those other activities necessary, appropriate, convenient or
incidental thereto.

                                       3
<PAGE>

   Each ONEOK Trust's business and affairs will be conducted by the property
trustee, the administrative trustee and the Delaware trustee (collectively
referred to in this prospectus as the securities trustees), which will be
appointed by ONEOK, as the holder of the common securities of each ONEOK Trust.
The property trustee of each ONEOK Trust will hold legal title to the junior
subordinated debentures issued by ONEOK on behalf of that ONEOK Trust and the
holders of the trust securities.

   Reference is made to the prospectus supplement relating to the preferred
securities of each ONEOK Trust for further information concerning that ONEOK
Trust.

                                USE OF PROCEEDS

   Each ONEOK Trust will use all proceeds received from the sale of its
preferred securities and common securities, which are together referred to as
the trust securities, to purchase junior subordinated debentures from ONEOK.

   Unless otherwise set forth in the applicable prospectus supplement, proceeds
from the sale of junior subordinated debentures will be used by ONEOK for
general corporate purposes, including, but not limited to, funding investments
in or extensions of credit to subsidiaries, repayments of indebtedness of ONEOK
or its subsidiaries, and possible acquisitions. The precise amount and timing
of the application of the funds will depend upon future requirements and the
availability of other funds to ONEOK and its subsidiaries. Management of ONEOK
expects that ONEOK and its subsidiaries will engage in additional financings as
needs arise.

                       RATIO OF EARNINGS TO FIXED CHARGES

   The following table shows the ratio of earnings to fixed charges and the
ratio of earnings to combined fixed charges and preferred stock dividend
requirements for ONEOK for the periods indicated, on an historical basis and
pro forma to give effect to the proposed merger with Southwest Gas:

<TABLE>
<CAPTION>
                          Nine Months Ended
                               May 31,            For the Years Ended August 31,
                         -------------------- ---------------------------------------
                          Merger               Merger
                         Pro Forma Historical Pro Forma          Historical
                         --------- ---------- --------- -----------------------------
                           1999       1999      1998    1998  1997  1996  1995  1994
                         --------- ---------- --------- ----- ----- ----- ----- -----
<S>                      <C>       <C>        <C>       <C>   <C>   <C>   <C>   <C>
Ratio of earnings to
 fixed charges..........   2.37x     5.44x      1.89x   5.50x 3.51x 3.28x 2.70x 2.52x
Ratio of earnings to
 combined fixed charges
 and preferred stock
 dividend requirements..   1.78x     2.47x      1.50x   2.52x 3.48x 3.24x 2.67x 2.49x
</TABLE>

   Merger pro forma information gives effect to the proposed merger transaction
with Southwest Gas and is presented as if the proposed merger transaction had
occurred as of the beginning of the applicable period.

   For purposes of computing the ratio of earnings to fixed charges, "earnings"
consists of net income plus fixed charges and income taxes. "Fixed charges"
consists of interest charges, the representative interest portion of operating
leases, preferred securities distributions of a subsidiary and the amortization
of debt issue costs.

   For purposes of computing the ratio of earnings to combined fixed charges
and preferred dividend requirements, "earnings" consists of net income plus
fixed charges and income taxes. "Fixed charges" consists of interest charges,
the amortization of debt issue costs, the representative interest portion of
operating leases and preferred securities distributions of a subsidiary.
"Preferred stock dividend requirements" consists of the pre-tax preferred stock
dividend requirement.

                                       4
<PAGE>

                    ACCOUNTING TREATMENT OF THE ONEOK TRUSTS

   For financial reporting purposes, each ONEOK Trust will be treated as a
subsidiary of ONEOK and, accordingly, the accounts of each ONEOK Trust will be
included in the consolidated financial statements of ONEOK. The preferred
securities will be presented as a separate line item in the consolidated
balance sheet of ONEOK, and appropriate disclosures concerning the preferred
securities, the preferred securities guarantee and the junior subordinated
debentures will be included in the notes to the consolidated financial
statements. For financial reporting purposes, ONEOK will record distributions
payable on the preferred securities as an expense.

                    DESCRIPTION OF THE PREFERRED SECURITIES

   Each ONEOK Trust may issue only one series of preferred securities having
terms described in the prospectus supplement relating thereto. The trust
agreement of each ONEOK Trust will authorize the administrative trustee, on
behalf of the trust, to issue the preferred securities. The preferred
securities of each ONEOK Trust will have those terms, including distributions,
redemption, voting, liquidation rights and other preferred, deferral or special
rights or restrictions as shall be set forth in the trust agreement of that
ONEOK Trust. Reference is made to the prospectus supplement relating to the
preferred securities of a ONEOK Trust for specific terms, including:

  .  the distinctive designation of those preferred securities;

  .  the number of preferred securities issued by that ONEOK Trust;

  .  the annual distribution rate (or method of determining such rate) for
     preferred securities of that ONEOK Trust and the date or dates on which
     distributions shall be payable;

  .  whether distributions on such preferred securities shall be cumulative
     and, in the case of preferred securities having cumulative distribution
     rights, the date or dates, or method of determining the date or dates,
     from which distributions will be cumulative;

  .  the amount or amounts that shall be paid out of the assets of that ONEOK
     Trust to the holders of those preferred securities upon voluntary or
     involuntary dissolution, winding-up or termination of that ONEOK Trust;

  .  the obligation, if any, of that ONEOK Trust to purchase or redeem those
     preferred securities and the price or prices at which, the period or
     periods within which, and the terms and conditions upon which those
     preferred securities will be purchased or redeemed, in whole or in part,
     pursuant to that obligation;

  .  the voting rights, if any, of those preferred securities in addition to
     those required by law, including any requirement for the approval by the
     holders of preferred securities as a condition to specified action or
     amendments to the trust agreement of that ONEOK Trust;

  .  the rights, if any, to defer distributions on the preferred securities
     by extending the interest payment period on the related junior
     subordinated debentures; and

  .  any other relative rights, preferences, privileges, limitations or
     restrictions of those preferred securities not inconsistent with the
     trust agreement of that ONEOK Trust or applicable law.

All preferred securities offered hereby will be guaranteed by ONEOK to the
extent set forth under "Description of the Preferred Securities Guarantees."
Any material United States federal income tax considerations applicable to an
offering of preferred securities will be described in the prospectus supplement
relating thereto.

                                       5
<PAGE>

               DESCRIPTION OF THE JUNIOR SUBORDINATED DEBENTURES

   Set forth below is a description of the general terms of the junior
subordinated debentures. The following description does not purport to be
complete and is subject to, and is qualified in its entirety by reference to,
the junior subordinated indenture to be entered into among ONEOK, and
             , as indenture trustee, as to be supplemented by a supplemental
indenture thereto establishing the junior subordinated debentures of each
series, the forms of which are filed as exhibits to the registration statement
of which this prospectus forms a part. The terms of the junior subordinated
debentures will include those stated in the junior subordinated indenture and
those made a part of the junior subordinated indenture by reference to the
Trust Indenture Act. Some capitalized terms used herein are defined in the
junior subordinated indenture.

General

   The junior subordinated debentures will be issued as unsecured junior
subordinated debt securities under the junior subordinated indenture. The
junior subordinated indenture does not limit the aggregate principal amount of
junior subordinated debentures that may be issued thereunder and provides that
junior subordinated debentures may be issued from time to time in one or more
series pursuant to an indenture supplemental to the junior subordinated
indenture.

   Reference is made to the prospectus supplement that will accompany this
prospectus for the following terms of the series of junior subordinated
debentures being offered thereby:

  .  the title of those junior subordinated debentures;

  .  any limit on the aggregate principal amount of those junior subordinated
     debentures;

  .  the date or dates on which the principal of those junior subordinated
     debentures is payable;

  .  the rate or rates at which those junior subordinated debentures shall
     bear interest and Additional Interest (as defined below), if any, the
     interest payment dates on which that interest shall be payable, the
     right of ONEOK to defer or extend those interest payments dates, and the
     regular record date for the interest payable on any interest payment
     date or the method by which any of the foregoing will be determined;

  .  the place or places where the principal of and premium, if any, and
     interest on those junior subordinated debentures shall be payable;

  .  the period or periods within which, the price or prices at which and the
     terms and conditions on which those junior subordinated debentures may
     be redeemed, in whole or in part, at the option of ONEOK;

  .  the obligation or right, if any, of ONEOK to redeem, repay or purchase
     those junior subordinated debentures;

  .  the denominations in which those junior subordinated debentures may be
     issued, if other than denominations of $25 and any integral multiple
     thereof;

  .  if other than the principal amount thereof, the portion of the principal
     amount of those junior subordinated debentures which shall be payable
     upon declaration of acceleration of the maturity thereof;

  .  any deletions from, modifications of or additions to the events of
     default or covenants of ONEOK as provided in the related junior
     subordinated indenture;

  .  whether those junior subordinated debentures shall initially be issued
     in whole or in part in the form of a global security; and

  .  any other terms of those junior subordinated debentures.

                                       6
<PAGE>

The terms of each series of junior subordinated debentures issued to a ONEOK
Trust will correspond to those of the related preferred securities of that
ONEOK Trust as described in the prospectus supplement relating to those
preferred securities.

   The junior subordinated indenture does not contain provisions that afford
holders of junior subordinated debentures protection in the event of a highly
leveraged transaction involving ONEOK.

Subordination

   The junior subordinated debentures are subordinated and junior in right of
payment to all Senior Debt (as defined below) of ONEOK. No payment of principal
of, or premium, if any, or interest on (including Additional Interest) the
junior subordinated debentures may be made if (1) a default has occurred and is
continuing in the payment of principal of or premium, if any, or interest on
any Senior Debt of ONEOK or (2) if any event of default with respect to Senior
Debt of ONEOK has occurred and is continuing and has resulted in Senior Debt
becoming or being declared due and payable prior to the date on which it would
otherwise have become due and payable, unless and until the event of default
shall have been cured or waived or shall have ceased to exist and acceleration
shall have been rescinded or annulled, or (3) any judicial proceeding is
pending with respect to any default in payment or event of default. In case of
the pendency of any receivership, insolvency, liquidation, bankruptcy,
reorganization or other judicial proceeding relative to ONEOK, the holders of
Senior Debt of ONEOK will be entitled to receive payment in full of all amounts
due or to become due on or in respect of all Senior Debt before the holders of
the junior subordinated debentures are entitled to receive or retain any
payment or distribution. Subject to the prior payment of all Senior Debt, the
rights of the holders of the junior subordinated debentures will be subrogated
to the rights of the holders of Senior Debt to receive payments and
distributions applicable to the Senior Debt until all amounts owing on the
junior subordinated debentures are paid in full. ONEOK had $938 million of
Senior Debt outstanding at May 31, 1999.

   The term "Senior Debt" means, with respect to any person, the principal of
and premium, if any, and interest, if any, on Debt of that person, whether
incurred on or prior to the date of the junior subordinated indenture or
thereafter incurred, unless, in the instrument creating or evidencing the same
or pursuant to which the same is outstanding, it is provided that those
obligations are not superior in right of payment to the junior subordinated
debentures or to other Debt which ranks equally with, or subordinated to, the
junior subordinated debentures. For this purpose, interest includes interest
accruing on or after the filing of any petition in bankruptcy or for
reorganization relating to a person, whether or not the claim for post-petition
interest is allowed in a proceeding. Senior Debt shall not be deemed to
include, in any event,

  .  any Debt of that person which, when incurred and without respect to any
     election under Section 1111(b) of the Bankruptcy Reform Act of 1978, was
     without recourse to that person;

  .  any Debt of that person to its direct and indirect subsidiaries;

  .  Debt to any employee of that person; and

  .  with respect to ONEOK, any junior subordinated debentures.

   The term "Debt" means, with respect to any person, whether recourse is to
all or a portion of the assets of that person and whether or not contingent,

   .  every obligation of that person for money borrowed;

  .  every obligation of that person evidenced by bonds, debentures, notes or
     other similar instruments, including obligations incurred in connection
     with the acquisition of property, assets or businesses;

  .  every reimbursement obligation of that person with respect to letters of
     credit, bankers' acceptances or similar facilities issued for the
     account of that person;

  .  every obligation of that person issued or assumed as the deferred
     purchase price of property or services, but excluding trade accounts
     payable or accrued liabilities arising in the ordinary course of
     business;

                                       7
<PAGE>

  .  every capital lease obligation of that person;

  .  all indebtedness of that person, whether incurred on or prior to the
     date of the junior subordinated indenture or thereafter incurred, for
     claims in respect of derivative products, including interest rate,
     foreign exchange rate and commodity forward contracts, options and swaps
     and similar arrangements; and

  .  every obligation of the type referred to in each clause above of another
     person and all dividends and operating lease payments of another person
     the payment of which, in either case, that person has guaranteed or is
     responsible or liable for, directly or indirectly, as obligor or
     otherwise.

Additional Interest

   "Additional Interest" is defined in the junior subordinated indenture as the
interest, if any, that will accrue on any interest on the junior subordinated
debentures of any series the payment of which has not been made on the
applicable interest payment date and which will accrue at the rate per annum
specified or determined as specified in those junior subordinated debentures.

Covenants

   ONEOK covenants in the junior subordinated indenture, for the benefit of the
holders of each series of junior subordinated debentures, that, (1) if at such
time as ONEOK shall have given notice of its election to extend an interest
payment period for that series of junior subordinated debentures and the
extension shall be continuing, (2) if at such time as ONEOK has actual
knowledge that ONEOK is in default with respect to its payment or other
obligations under the preferred securities guarantee with respect to the trust
securities, if any, related to that series of junior subordinated debentures,
or (3) if at such time an event of default with respect to that series of
junior subordinated debentures shall have occurred and be continuing, ONEOK
shall not:

  .  declare or pay any dividend or make any distributions with respect to,
     or redeem, purchase, acquire or make a liquidation payment with respect
     to, any of its capital stock, or

  .  make any payment of interest, principal or premium, if any, on or repay,
     repurchase or redeem any debt securities issued by it which rank equally
     with or junior to the junior subordinated debentures or make any
     guarantee payments with respect to any guarantee by it of debt
     securities of any subsidiary if the guarantee is equal to or junior in
     interest to the junior subordinated debentures other than

    -- dividends or distributions in common stock,

    -- any declaration of a dividend in connection with implementation of
       any stockholders' rights plan, or the issuance of rights, stock or
       other property under that plan, or the redemption, repurchase or
       other acquisition of those rights pursuant thereto,

    -- payments under any preferred securities guarantee, or

    -- purchases of common stock in connection with any of its benefit
       plans.

   The junior subordinated indenture further provides that, for so long as the
trust securities of any ONEOK Trust remain outstanding, ONEOK covenants

  .  to directly or indirectly maintain 100% ownership of the common
     securities of that ONEOK Trust; provided, however, that any permitted
     successor of ONEOK under the junior subordinated indenture may succeed
     to ONEOK's ownership of those common securities, and

  .  to use its reasonable efforts to cause that ONEOK Trust

    -- to remain a statutory business trust, except in connection with the
       distribution of junior subordinated debentures to the holders of
       ONEOK trust securities in liquidation of that ONEOK Trust, or certain
       mergers, consolidations or amalgamations permitted by the related
       trust agreement, and

    -- to otherwise continue to be classified as a grantor trust for United
       States federal income tax purposes.

                                       8
<PAGE>

Satisfaction and Discharge

   The junior subordinated indenture will cease to be of further effect and
ONEOK will be deemed to have satisfied and discharged all of its obligations
under the junior subordinated indenture when (1) all outstanding junior
subordinated debentures have become due and payable, or will become due and
payable within one year, by reason of their maturity or a redemption date, and
(2) ONEOK deposits with the indenture trustee, in trust, funds that are
sufficient to pay and discharge all remaining indebtedness on the outstanding
junior subordinated debentures; provided, however, that ONEOK will remain
obligated to pay all other amounts due under the junior subordinated indenture
and to perform certain ministerial tasks as described in the junior
subordinated indenture.

   Unless otherwise provided in a supplemental indenture setting forth the
terms of a series of junior subordinated debentures, ONEOK will be deemed to
have paid and discharged the entire indebtedness on all of the outstanding
junior subordinated debentures of that series when (1) ONEOK deposits with the
indenture trustee, in trust, funds that are sufficient to pay and discharge all
remaining indebtedness on the outstanding junior subordinated debentures of
that series to the stated maturity or any redemption date, (2) ONEOK has paid
all other sums payable with respect to the outstanding junior subordinated
debentures of that series, and (3) ONEOK has satisfied certain other
requirements intended to ensure that the payment and discharge will not have
any adverse United States federal income tax consequences to holders of
preferred securities.

Events of Default

   The junior subordinated indenture provides that any one or more of the
following described events with respect to the junior subordinated debentures
of any series, which has occurred and is continuing, constitutes an event of
default for the junior subordinated debentures of that series:

  .  failure of ONEOK for 30 days to pay interest on the junior subordinated
     debentures of that series, including any Additional Interest, when due
     and payable; provided, however, that a valid extension of the interest
     payment period by ONEOK will not constitute a default in the payment of
     interest for this purpose; or

  .  failure of ONEOK to pay principal or premium, if any, on the junior
     subordinated debentures of that series when due at maturity; or

  .  default in the performance of, or breach in any material respect of, any
     covenant or warranties of ONEOK in the junior subordinated indenture
     (other than a covenant or warranty which has expressly been dealt with
     in clauses (a), (b) or (d)) for 90 days after written notice to ONEOK
     from the indenture trustee or to ONEOK and the indenture trustee from
     the holders of at least 25% in principal amount of the outstanding
     junior subordinated debentures of that series; or

  .events of bankruptcy, insolvency, or reorganization of ONEOK.

   The holders of a majority in aggregate outstanding principal amount of the
junior subordinated debentures of any series have the right to direct the time,
method and place of conducting any proceeding for any remedy available to the
indenture trustee with respect to the junior subordinated debentures of that
series, subject to certain limitations. If a Junior Subordinated Indenture
Event of Default (other than pursuant to clause (d) above) occurs and is
continuing with respect to the junior subordinated debentures of any series,
then the indenture trustee or the holders of not less than 25% in aggregate
outstanding principal amount of the junior subordinated debentures of that
series may declare the principal amount thereof due and payable immediately by
notice in writing to ONEOK and to the indenture trustee, if given by the
holders, and upon that declaration the principal amount shall become
immediately due and payable. If a Junior Subordinated Indenture Event of
Default pursuant to clause (d) above occurs and is continuing with respect to
the junior subordinated debentures of any series, the principal amount of all
junior subordinated debentures of that series will automatically become
immediately due and payable. At any time after a declaration of acceleration
with respect to the junior subordinated debentures of any series has been made
and before a judgment or decree for payment of the

                                       9
<PAGE>

money due has been obtained, the holders of a majority in aggregate outstanding
principal amount of the junior subordinated debentures of that series may
rescind and annul the declaration and its consequences if the default has been
cured or waived and ONEOK has paid or deposited with the indenture trustee a
sum sufficient to pay all matured installments of interest, including any
Additional Interest, and principal due otherwise than by acceleration and all
sums paid or advanced by the indenture trustee, including reasonable
compensation and expenses of the indenture trustee.

   A holder of preferred securities may institute a legal proceeding directly
against ONEOK, without first instituting a legal proceeding against the
property trustee or any other person or entity, for enforcement of payment to
that holder of principal of or interest on the junior subordinated debentures
of the related series having a principal amount equal to the aggregate stated
liquidation amount of the preferred securities of that holder on or after the
due dates specified in the junior subordinated debentures of that series.

   The holders of a majority in aggregate outstanding principal amount of the
junior subordinated debentures of any series may, on behalf of the holders of
all the junior subordinated debentures of that series, waive any past default
with respect to that series, except (1) a default in the payment of principal
or interest, or (2) a default of a covenant or provision which under the junior
subordinated indenture cannot be modified or amended without the consent of the
holder of each outstanding junior subordinated debentures of that series
affected thereby. See "--Modification" below.

Registration and Transfer

   ONEOK will not be required to

  .  issue, transfer or exchange junior subordinated debentures of any series
     during a period of 15 days immediately preceding the date notice is
     given identifying the junior subordinated debentures of that series
     called for redemption, or

  .  transfer or exchange any junior subordinated debentures so selected for
     redemption, in whole or in part, except the unredeemed portion of any
     junior subordinated debentures being redeemed in part.

Payment and Paying Agent

   Payment of principal of any junior subordinated debentures will be made only
against surrender to the paying agent of those junior subordinated debentures.
Principal of and interest on junior subordinated debentures will be payable,
subject to any applicable laws and regulations, at the office of the paying
agent or paying agents as ONEOK may designate from time to time, except that,
at the option of ONEOK, payment of any interest may be made by wire transfer or
by check mailed to the address of the person entitled thereto as such address
shall appear in the security register maintained by               under the
junior subordinated indenture. Payment of interest on junior subordinated
debentures on any interest payment date will be made to the person in whose
name the junior subordinated debentures are registered at the close of business
on the record date for that interest payment.

   The indenture trustee will act as paying agent with respect to the junior
subordinated debentures. ONEOK may at any time designate additional paying
agents or rescind the designation of any paying agents or approve a change in
the office through which any paying agent acts.

   All monies paid by ONEOK to a paying agent for the payment of the principal
of or interest on the junior subordinated debentures of any series which remain
unclaimed at the end of two years after that principal or interest shall have
become due and payable will be repaid to ONEOK, and the holder of those junior
subordinated debentures may thereafter look only to ONEOK for payment thereof.

Modification

   The junior subordinated indenture contains provisions permitting ONEOK and
the indenture trustee, with the consent of the holders of a majority in
principal amount of the outstanding junior subordinated debentures

                                       10
<PAGE>

of each series affected thereby, to modify the junior subordinated indenture or
the rights of the holders of the junior subordinated debentures of that series.
ONEOK and the indenture trustee may not, however, modify the junior
subordinated indenture, without the consent of the holder of each outstanding
junior subordinated debentures affected thereby, so as to:

  .  except pursuant to the terms of the junior subordinated indenture,
     change the stated maturity of the principal of, or any installment of
     principal of or interest on, any junior subordinated debentures, or
     reduce the principal amount thereof or the rate of interest, including
     Additional Interest, thereon or any premium payable upon the redemption
     thereof, or impair the right to institute suit for the enforcement of
     any such payment on or after the stated maturity thereof or, in the case
     of redemption, on or after the redemption date, or

  .  reduce the percentage of principal amount of the outstanding junior
     subordinated debentures of any series, the consent of whose holders is
     required for any such supplemental indenture, or the consent of whose
     holders is required for any waiver of compliance with provisions of the
     junior subordinated indenture or defaults thereunder and their
     consequences provided for in the junior subordinated indenture, or

  .  modify any of the provisions of the junior subordinated indenture
     relating to supplemental indentures, waiver of past defaults, or waiver
     of covenants, except to increase any percentage or to provide that other
     provisions of the junior subordinated indenture cannot be modified or
     waived without the consent of the holder of each outstanding junior
     subordinated debentures affected thereby, or

  .  modify the provisions of the junior subordinated indenture with respect
     to the subordination of the junior subordinated debentures in a manner
     adverse to such holder.

   In addition, when junior subordinated debentures of a series are held by a
ONEOK Trust, the consent of the holders of a majority of the liquidation amount
of outstanding preferred securities of that ONEOK Trust is required to modify
the junior subordinated indenture in a manner that adversely affects in any
material respect the interests of any holder of that ONEOK Trust's preferred
securities. In addition, ONEOK and the indenture trustee may execute, without
the consent of any holders of junior subordinated debentures, any supplemental
indenture for other usual purposes, including the creation of any new series of
junior subordinated debentures.

Consolidation, Merger, Conveyance, Transfer or Lease

   ONEOK may not consolidate with or merge into any other person or convey,
transfer or lease its properties and assets substantially as an entirety to any
person, unless

  .  the corporation or entity formed by such consolidation or into which
     ONEOK is merged or which acquires by conveyance or transfer, or which
     leases, the properties and assets of ONEOK substantially as an entirety,
     is a corporation, partnership or trust that expressly assumes, by
     supplemental indenture executed and delivered to the indenture trustee,
     the payment of the principal of and premium, if any, and interest
     (including Additional Interest) on all the junior subordinated
     debentures and the performance of every covenant of the junior
     subordinated indenture on the part of ONEOK to be performed or observed;

  .  immediately after giving effect to the transaction, no Junior
     Subordinated Indenture Event of Default, and no event that, after notice
     or lapse of time or both, would become a Junior Subordinated Indenture
     Event of Default, shall have happened and be continuing;

  .  ONEOK has delivered to the indenture trustee an officers' certificate
     and an opinion of counsel, each stating that the transaction complies
     with the provisions of the junior subordinated indenture governing
     consolidation, merger, conveyance, transfer or lease and that all
     conditions precedent thereto have been complied with; and

  .  in the case of junior subordinated debentures issued to a ONEOK Trust,
     the transaction is permitted under the related preferred securities
     guarantee and does not give rise to any breach or violation of the
     related trust agreement or preferred securities.

                                       11
<PAGE>

Information Concerning the Indenture Trustee

   The indenture trustee, except during the continuance of a Junior
Subordinated Indenture Event of Default, undertakes to perform, with respect to
junior subordinated debentures of a series, only those duties as are
specifically set forth in the junior subordinated indenture and, in case a
Junior Subordinated Indenture Event of Default has occurred and is continuing,
the indenture trustee is required to exercise, with respect to junior
subordinated debentures of that series, the same degree of care as a prudent
individual would exercise in the conduct of his or her own affairs. Subject to
such provision, the indenture trustee is under no obligation to exercise any of
the powers vested in it by the junior subordinated indenture at the request of
any holder of junior subordinated debentures of any series, unless offered
reasonable indemnity by that holder against the costs, expenses and liabilities
which might be incurred thereby. The indenture trustee is not required to
expend or risk its own funds or otherwise incur any financial liability in the
performance of its duties if the indenture trustee reasonably believes that
repayment or adequate indemnity is not reasonably assured to it.

             , the indenture trustee, also serves as property trustee and
guarantee trustee. ONEOK and some of its subsidiaries maintain deposit accounts
and banking relationships with the indenture trustee.

Governing Law

   The junior subordinated indenture and the junior subordinated debentures
will be governed by, and construed in accordance with, the internal laws of the
State of New York.

               DESCRIPTION OF THE PREFERRED SECURITIES GUARANTEES

   Set forth below is a summary of information concerning the preferred
securities guarantees that will be executed and delivered by ONEOK for the
benefit of the holders of preferred securities of the respective ONEOK Trusts.
Each preferred securities guarantee will be qualified as an indenture under the
Trust Indenture Act.            will act as indenture trustee under each
preferred securities guarantee for purposes of the Trust Indenture Act. The
terms of the preferred securities guarantees will be those set forth therein
and those made part thereof by the Trust Indenture Act. The following summary
does not purport to be complete and is subject in all respects to the
provisions of, and is qualified in its entirety by reference to, the preferred
securities guarantees, the form of which is filed as an exhibit to the
registration statement of which this prospectus forms a part, and the Trust
Indenture Act. Each preferred securities guarantee will be held by the
guarantee trustee for the benefit of holders of the preferred securities to
which it relates.

General

   Pursuant to each preferred securities guarantee, ONEOK will irrevocably and
unconditionally agree, to the extent set forth therein, to pay in full, to the
holders of the related preferred securities, the Guarantee Payments (as defined
below), to the extent not paid by, or on behalf of, the related ONEOK Trust,
regardless of any defense, right of set-off or counterclaim that ONEOK may have
or assert against any person. The following payments or distributions on the
preferred securities of any ONEOK Trust to the extent not paid or made by, or
on behalf of, such ONEOK Trust will be subject to the preferred securities
guarantee related thereto:

  .  any accrued and unpaid distributions required to be paid on the
     preferred securities of that ONEOK Trust but if and only to the extent
     that the ONEOK Trust has funds legally and immediately available
     therefor,

  .  the redemption price on any preferred security, which is equal to the
     liquidation amount of the preferred security plus any accrued and unpaid
     distributions to the date of redemption, but if and only to the extent
     that ONEOK Trust has funds legally and immediately available therefor,
     and

                                       12
<PAGE>

  .  upon a liquidation, winding-up or termination of that ONEOK Trust, other
     than in connection with the distribution of junior subordinated
     debentures to the holders of trust securities of such ONEOK Trust, the
     lesser of (A) the aggregate of the liquidation amount and all accrued
     and unpaid distributions on the preferred securities of that ONEOK Trust
     to the date of payment, to the extent that ONEOK Trust has funds legally
     and immediately available therefor, and (B) the amount of assets of that
     ONEOK Trust remaining available for distribution to holders of preferred
     securities of that ONEOK Trust in liquidation.

   The foregoing constitute Guarantee Payments. ONEOK's obligation to make a
Guarantee Payment may be satisfied by direct payment of the required amounts by
ONEOK to the holders of the related preferred securities or by causing the
related ONEOK Trust to pay such amounts to those holders.

   Each preferred securities guarantee will be a guarantee of the Guarantee
Payments with respect to the related preferred securities from the time of
issuance of those preferred securities, but will not apply to the payment of
distributions and other payments on those preferred securities when the related
ONEOK Trust does not have sufficient funds legally and immediately available to
make such distributions or other payments. If ONEOK does not make interest
payments on the junior subordinated debentures held by the property trustee
under any ONEOK Trust, that ONEOK Trust will not make distributions on its
preferred securities.

Subordination

   ONEOK's obligations under each preferred securities guarantee to make the
Guarantee Payments will constitute an unsecured obligation of ONEOK and will
rank

  .  subordinate and junior in right of payment to all other liabilities of
     ONEOK, except those obligations or liabilities that rank equally or
     subordinate by their terms,

  .  equally with the most senior preferred or preference stock hereafter
     issued by ONEOK and

  .  senior to all common stock of ONEOK.

   The terms of the preferred securities will provide that each holder of
preferred securities by acceptance thereof agrees to the subordination
provisions and other terms of the preferred securities guarantee related
thereto. ONEOK has outstanding common stock that ranks junior to the preferred
securities guarantees.

   Each preferred securities guarantee will constitute a guarantee of payment
and not of performance or collection. That means the guaranteed party may
institute a legal proceeding directly against the guarantor --in this case,
ONEOK-- to enforce its rights under the guarantee without first instituting a
legal proceeding against any other person or entity.

Amendments and Assignment

   Except for changes that do not materially and adversely affect the rights of
holders of the related preferred securities, in which case no consent will be
required, each preferred securities guarantee may be amended only with the
prior approval of the holders of a majority in liquidation amount of the
outstanding related preferred securities. The manner of obtaining any approval
of holders will be as set forth in an accompanying prospectus supplement. All
guarantees and agreements contained in each preferred securities guarantee will
bind the successors, assigns, receivers, trustees and representatives of ONEOK
and shall inure to the benefit of the holders of the related preferred
securities then outstanding.

Termination

   Each preferred securities guarantee will terminate and be of no further
force and effect as to the related preferred securities upon full payment of
the redemption price of all of the related preferred securities, upon
distribution of junior subordinated debentures to the holders of those
preferred securities, or upon full payment of the amounts payable upon
liquidation of the related ONEOK Trust. Each preferred securities guarantee
will

                                       13
<PAGE>

continue to be effective or will be reinstated, as the case may be, if at any
time any holder of the related preferred securities must restore payment of any
sums paid on those preferred securities or under that preferred securities
guarantee.

Events of Default

   An event of default under each preferred securities guarantee will occur
upon the failure by ONEOK to perform any of its payment or other obligations
thereunder, subject to applicable grace periods. The holders of a majority in
liquidation amount of the preferred securities to which any preferred
securities guarantee relates have the right to direct the time, method and
place of conducting any proceeding for any remedy available to the guarantee
trustee or to direct the exercise of any trust or power conferred upon the
guarantee trustee under that preferred securities guarantee. Any holder of the
related preferred securities may institute a legal proceeding directly against
ONEOK to enforce its rights under a preferred securities guarantee without
first instituting a legal proceeding against the guarantee trustee or any other
person or entity. The holders of a majority in liquidation amount of preferred
securities of any series may, by vote, on behalf of the holders of all the
preferred securities of that series, waive any past event of default and its
consequences.

Information Concerning the Guarantee Trustee

   The guarantee trustee, prior to the occurrence of any event of default with
respect to any preferred securities guarantee and after the curing or waiving
of all events of default with respect to that preferred securities guarantee,
undertakes to perform only such duties as are specifically set forth in that
preferred securities guarantee and, in case an event of default has occurred,
is required to exercise the same degree of care as a prudent individual would
exercise in the conduct of his or her own affairs. Subject to such provisions,
the guarantee trustee is under no obligation to exercise any of the powers
vested in it by any preferred securities guarantee at the request of any holder
of the related preferred securities, unless offered reasonable indemnity
against the costs, expenses and liabilities which might be incurred thereby.
The guarantee trustee is not required to expend or risk its own funds or
otherwise incur any financial liability in the performance of its duties if the
guarantee trustee reasonably believes that repayment or adequate indemnity is
not reasonably assured to it.

                       , the guarantee trustee, also serves as property trustee
and as indenture trustee. ONEOK and some of its subsidiaries maintain deposit
accounts and banking relationships with the guarantee trustee.

Governing Law

   Each preferred securities guarantee will be governed by, and construed in
accordance with, the internal laws of the State of New York.

Agreements as to Expenses and Liabilities

   Pursuant to an agreement as to expenses and liabilities to be entered into
by ONEOK under each trust agreement, ONEOK will irrevocably and unconditionally
guarantee to each person or entity to whom each ONEOK Trust becomes indebted or
liable the full payment of any indebtedness, expenses or liabilities of that
ONEOK Trust, other than obligations of that ONEOK Trust to pay to the holders
of the related preferred securities or other similar interests in that ONEOK
Trust the amounts due such holders pursuant to the terms of such preferred
securities or such other similar interests, as the case may be.

                                       14
<PAGE>

RELATIONSHIP AMONG THE PREFERRED SECURITIES, THE JUNIOR SUBORDINATED DEBENTURES
                    AND THE PREFERRED SECURITIES GUARANTEES

   As long as payments of interest and other payments are made when due on each
series of junior subordinated debentures issued to a ONEOK Trust, those
payments will be sufficient to cover distributions and payments due on the
related trust securities of that ONEOK Trust primarily because

  .  the aggregate principal amount of each series of junior subordinated
     debentures will be equal to the sum of the aggregate stated liquidation
     amount of the related trust securities;

  .  the interest rate and interest and other payment dates on each series of
     junior subordinated debentures will match the distribution rate and
     distribution and other payment dates for the related preferred
     securities;

  .  ONEOK is required to pay for all costs and expenses of each ONEOK Trust
     pursuant to the agreements as to expenses and liabilities; and

  .  each trust agreement will provide that the securities trustees
     thereunder shall not cause or permit the trust to, among other things,
     engage in any activity that is not consistent with the purposes of the
     trust.

   Payments of distributions, to the extent funds therefor are legally and
immediately available, and other payments due on the preferred securities, to
the extent funds therefor are legally and immediately available, will be
guaranteed by ONEOK as and to the extent set forth under "Description of the
Preferred Securities Guarantees." If ONEOK does not make interest payments on
any series of junior subordinated debentures, it is not expected that the
related ONEOK Trust will have sufficient funds to pay distributions on its
preferred securities. Each preferred securities guarantee is a guarantee from
the time of its issuance, but does not apply to any payment of distributions
unless and until the related ONEOK Trust has sufficient funds legally and
immediately available for the payment of those distributions.

   If a Junior Subordinated Indenture Event of Default occurs and is continuing
with respect to any series of junior subordinated debentures and the indenture
trustee fails or the holders of not less than 25% in principal amount of the
outstanding junior subordinated debentures of that series fail to declare the
principal of all of the junior subordinated debentures of that series to be
immediately due and payable, then the holders of at least 25% in liquidation
amount of the related preferred securities then outstanding will have the right
by written notice to ONEOK and the indenture trustee to declare such principal
immediately due and payable. Notwithstanding the foregoing, a holder of
preferred securities may institute a legal proceeding directly against ONEOK,
without first instituting a legal proceeding against the property trustee or
any other person or entity, for enforcement of payment to that holder of
principal of or interest on junior subordinated debentures of the related
series having a principal amount equal to the aggregate stated liquidation
amount of the preferred securities of that holder on or after the due dates
specified in the junior subordinated debentures of that series.

   If ONEOK fails to make payments under any preferred securities guarantee,
that preferred securities guarantee provides a mechanism whereby the holders of
the preferred securities to which that preferred securities guarantee relates
may direct the guarantee trustee to enforce its rights thereunder. In addition,
any holder of preferred securities may institute a legal proceeding directly
against ONEOK to enforce its rights under the related preferred securities
guarantee without first instituting a legal proceeding against the guarantee
trustee or any other person or entity.

   Each preferred securities guarantee, the junior subordinated indenture, the
junior subordinated debentures of the related series, the related trust
agreement and the related agreement as to expenses and liabilities, as
described above, constitute a full and unconditional guarantee by ONEOK of the
payments due on the related series of preferred securities.

   Upon any voluntary or involuntary dissolution, winding-up or termination of
any ONEOK Trust, unless junior subordinated debentures of the related series
are distributed in connection therewith, the holders of

                                       15
<PAGE>

preferred securities of that ONEOK Trust will be entitled to receive, out of
assets legally available for distribution to holders, a liquidation
distribution in cash as described in the applicable prospectus supplement. Upon
any voluntary or involuntary liquidation or bankruptcy of ONEOK, the property
trustee, as holder of the related series of junior subordinated debentures,
would be a subordinated creditor of ONEOK, subordinated in right of payment to
all Senior Debt, but entitled to receive payment in full of principal and
interest, before any stockholders of ONEOK receive payments or distributions.
Because ONEOK is guarantor under each preferred securities guarantee and has
agreed to pay for all costs, expenses and liabilities of each ONEOK Trust,
other than the trust's obligations to holders of the preferred securities,
pursuant to the related agreement as to expenses and liabilities, the positions
of a holder of preferred securities and a holder of junior subordinated
debentures of the related series relative to other creditors and to
stockholders of ONEOK in the event of liquidation or bankruptcy of ONEOK would
be substantially the same.

   A default or event of default under any Senior Debt would not constitute a
default or Event of Default under the junior subordinated indenture. However,
in the event of payment defaults under, or acceleration of, Senior Debt, the
subordination provisions of the junior subordinated debentures provide that no
payments may be made on the junior subordinated debentures until the Senior
Debt has been paid in full or any payment default thereunder has been cured or
waived. Failure to make required payments on the junior subordinated debentures
of any series would constitute an Event of Default under the junior
subordinated indenture with respect to the junior subordinated debentures of
that series except that failure to make interest payments on the junior
subordinated debentures of that series will not be an Event of Default during
an extension period as described in the applicable prospectus supplement.

                                 ERISA MATTERS

   ONEOK and other affiliates of ONEOK and the property trustee and its
affiliates may each be considered a "party in interest," within the meaning of
the Employee Retirement Income Security Act of 1974, or a "disqualified
person," within the meaning of Section 4975 of the Internal Revenue Code with
respect to many employee benefit plans that are subject to ERISA or described
in Section 4975 of the Code. The purchase of offered securities by a Plan that
is subject to the fiduciary responsibility provisions of ERISA or the
prohibited transaction provisions of Section 4975 of the Code, including
individual retirement arrangements and other plans described in Section
4975(e)(1) of the Code, and with respect to which ONEOK, Inc. or any other
affiliate of ONEOK and the property trustee and its affiliates is a service
provider, or otherwise is a party in interest or a disqualified person, may
constitute or result in a prohibited transaction under ERISA or Section 4975 of
the Code, unless such offered securities are acquired under and in accordance
with an applicable exemption issued by the U.S. Department of Labor. In
addition, ERISA imposes specific requirements on fiduciaries of plans subject
to ERISA, namely, that they make prudent investments, diversify investments,
make investments in accordance with the terms of the plan documents and in the
best interests of plan participants and beneficiaries. In addition, a plan
fiduciary considering the purchase of offered securities should be aware that
the assets of the trust may be considered "plan assets" for ERISA purposes.
Therefore, a plan fiduciary should consider whether the purchase of offered
securities could result in a delegation of fiduciary authority to the property
trustee, and, if so, whether such a delegation of authority is permissible
under the plan's governing instrument or any investment management agreement
with the plan. In making this determination, it should be borne in mind that,
prior to an event of default under the junior subordinated indenture, the
property trustee will have only limited custodial and ministerial authority
with respect to trust assets. Any pension or other employee benefit plan
proposing to acquire any offered securities should determine that the offered
securities are an appropriate investment in light of ERISA's fiduciary
standards and consult with its counsel to determine that the investment is not
otherwise prohibited under ERISA or the Code.

                                       16
<PAGE>

                              PLAN OF DISTRIBUTION

   ONEOK may sell any series of junior subordinated debt securities and the
ONEOK Trusts may sell the preferred securities being offered hereby:

  .  directly to one or more purchasers.

  .  through agents designated from time to time.

  .  through underwriters or dealers or a group of underwriters.

  .  any combination of the foregoing.

The applicable prospectus supplement will set forth the terms of the offering,
including the name or names of any underwriters, the purchase price of the
offered securities and the proceeds to ONEOK or any ONEOK Trust from such sale,
any underwriting discounts and other items constituting underwriters'
compensation, any initial public offering price and any discounts or
concessions allowed or reallowed or paid to dealers and any securities
exchanges on which the offered securities may be listed. If a bidding or
auction process is used, it will be described in the applicable prospectus
supplement.

   If underwriters are used in the sale, offered securities will be acquired by
the underwriters for their own account and may be resold from time to time in
one or more transactions, including negotiated transactions, at a fixed public
offering price or at varying prices determined at the time of sale. The offered
securities may be offered to the public either through underwriting syndicates
represented by managing underwriters or by underwriters without a syndicate.
Unless otherwise set forth in the applicable prospectus supplement, the
obligations of the underwriters to purchase the offered securities will be
subject to conditions precedent, and the underwriters will be obligated to
purchase all the offered securities if any are purchased. Any initial public
offering price and any discounts or concessions allowed or reallowed or paid to
dealers may be changed from time to time.

   Offered securities may be sold directly by ONEOK or through agents
designated by ONEOK from time to time. Any agent involved in the offer or sale
of offered securities will be named, and any commissions payable by ONEOK to
any agents will be set forth, in the applicable prospectus supplement. Unless
otherwise indicated in the applicable prospectus supplement, any agent will be
acting on a best efforts basis for the period of its appointment.

   If so indicated in the applicable prospectus supplement, ONEOK will
authorize agents, underwriters or dealers to solicit offers by certain
specified institutions to purchase offered securities at the public offering
price set forth in such prospectus supplement pursuant to delayed delivery
contracts providing for payment and delivery on a specified date in the future.
The contracts will be subject only to those conditions set forth in the
applicable prospectus supplement and such prospectus supplement will set forth
the commission payable for the solicitation of the contracts.

   Any underwriters, dealers or agents participating in the distribution of
offered securities may be deemed to be underwriters and any discounts or
commissions received by them on the sale or resale of offered securities may be
deemed to be underwriting discounts and commissions under the Securities Act.
Agents and underwriters may be entitled under agreements entered into with
ONEOK to indemnification by ONEOK against certain liabilities, including
liabilities under the Securities Act, or to contribution with respect to
payments which the agents or underwriters may be required to make in respect to
contribution. Agents and underwriters may be customers of, engage in
transactions with, or perform services for, ONEOK in the ordinary course of
business.

   All offered securities will be a new issue of securities with no established
trading market. Certain Agents through whom, and underwriters to whom, offered
securities are sold by ONEOK for public offering and sale may make a market in
the offered securities, but the agents and underwriters will not be obligated
to do so and

                                       17
<PAGE>

may discontinue any market making at any time without notice. No assurance can
be given as to the liquidity of the trading market for any offered securities.

   Affiliates of ONEOK may use this prospectus and the related prospectus
supplement in connection with offers and sales of the offered securities in the
secondary market. These affiliates may act as principal or agent in those
transactions. Secondary market sales will be made at negotiated prices related
to market prices at the time of sale.

                                 LEGAL MATTERS

   Unless otherwise indicated in the applicable prospectus supplement, certain
matters of Delaware law relating to the validity of the preferred securities
will be passed upon by Richards, Layton & Finger, P.A., Wilmington, Delaware,
special Delaware counsel to the ONEOK Trusts. The validity of the preferred
securities guarantees and the junior subordinated debt securities and certain
other matters will be passed upon for ONEOK by Gable & Gotwals, Tulsa,
Oklahoma. Any underwriters or agents will be advised about other issues
relating to any offering by Jones, Day, Reavis & Pogue, Chicago, Illinois.
Jones, Day, Reavis & Pogue will rely on Gable & Gotwals as to matters of
Oklahoma law. Jones, Day, Reavis & Pogue from time to time acts as counsel to
ONEOK.

                                    EXPERTS

   The consolidated financial statements of ONEOK and its subsidiaries as of
August 31, 1998 and 1997, and for each of the years in the three-year period
ended August 31, 1998 have been incorporated by reference herein in reliance
upon the report of KPMG LLP, independent certified public accountants,
incorporated by reference herein, and upon the authority of said firm as
experts in accounting and auditing.

   The consolidated financial statements of Southwest Gas and its subsidiaries
as of December 31, 1998 and 1997, and for each of the years in the three-year
period ended December 31, 1998, incorporated by reference in
ONEOK's current report on Form 8-K dated April 15, 1999, incorporated by
reference herein, have been audited by Arthur Andersen LLP, independent public
accountants, as indicated in their report with respect thereto, and which are
incorporated by reference herein in reliance upon the authority of said firm as
experts in giving said report.

                                       18
<PAGE>

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

                              Preferred Securities

                             ONEOK Capital Trust I

                           % Preferred Trust Securities
                    Fully and Unconditionally Guaranteed by

                                  ONEOK, INC.

                            ----------------------
                             PROSPECTUS SUPPLEMENT

                            ----------------------

                            PaineWebber Incorporated

                            ----------------------

                                         , 1999

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>

                                    PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

   The estimated expenses of issuance and distribution, other than underwriting
discounts and commissions, to be borne by ONEOK are as follows:

<TABLE>
      <S>                                                              <C>
      Securities and Exchange Commission registration fee............. $ 83,400
      Fees of Trustees................................................        *
      New York Stock Exchange listing fee.............................        *
      Printing and engraving..........................................        *
      Rating agency fees..............................................        *
      Fees and expenses of counsel....................................        *
      Blue sky fees and expenses......................................        *
      Fees of accountants.............................................        *
      Miscellaneous...................................................        *
                                                                       --------
                                                                       $      *
                                                                       ========
</TABLE>
- --------
   *To be completed by amendment

Item 15. Indemnification of Directors and Officers.

   The Company, as an Oklahoma corporation, is empowered by section 1031 of the
Oklahoma General Corporation Act, subject to the procedures and limitations
stated therein, to indemnify any person against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with any threatened, pending or completed action,
suit or proceeding in which such person is made or threatened to be made a
party by reason of his being or having been a director, officer, employee or
agent of the Company. The statute provides that indemnification pursuant to its
provisions is not exclusive of other rights of indemnification to which a
person may be entitled under any bylaw, agreement, vote of shareholders, or
disinterested directors, or otherwise. Article VIII of the By-laws of the
Company provides that directors and officers of the Company shall be
indemnified by the Company to the fullest extent permitted by Oklahoma law as
now or hereafter enforced, including the advance of related expenses. If any
determination is required under applicable law as to whether a director or
officer is entitled to indemnification, such determination shall be made by the
Board, by vote of a quorum of disinterested directors, or by independent legal
counsel by written opinion or by shareholders.

   The Certificate of Incorporation of the Company provides that a director of
the corporation shall not be personally liable to the corporation or its
shareholders for monetary damages for breach of fiduciary duty as a director,
except for liability for (1) any breach of the director's duty of loyalty to
the corporation or its shareholders, (2) acts or omissions not in good faith or
which would involve intentional misconduct or a knowing violation of law, (3)
payment of unlawful dividends or unlawful stock purchases or redemptions, or
(4) any transaction from which the director derived an improper personal
benefit.

   Pursuant to Article VIII of the By-laws of the Company, upon authorization
and determination (1) by the board of directors by a majority of a quorum
consisting of directors who were not parties to the action, suit, or proceeding
involved; (2) if such a quorum is not obtainable, or even if obtainable and a
quorum of disinterested directors so directs, by independent counsel in a
written opinion; or (3) by the stockholders, the Company is obligated to
indemnify any person who incurs liability by reason of the fact that he is or
was a director, officer, employee, or agent of the Company, or is or was
serving at its request as a director, officer, employee, or agent of another
corporation, partnership, joint venture, trust or other enterprise, or as a
member of any committee or similar body, if he acted in good faith and in a
manner he reasonably believed to be in or not opposed to the best interests of
the Company, and with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful. However, in an action by
or in the right of the Company, no indemnification will be made if such person
shall be adjudged to be liable to the Company, unless such indemnification is
allowed by a court of competent jurisdiction.

                                      II-1
<PAGE>

   Under an insurance policy obtained by the Company, coverage of Company
officers and directors against liability for neglect, errors, omissions, or
breaches of duty in their capacities as such is provided for both the Company,
to the extent that it is obligated to indemnify such officers and directors,
and the officers and directors themselves. Such coverage is provided in the
amount of $75,000,000, with a retained limit by the Company of $250,000. The
insurance company is obligated to pay any loss in excess of the $250,000
retained limit and defense costs from the first dollar, up to the policy limit
of $75,000,000. Among the policy exclusions are those which exclude coverage
for accounting for profits made within the meaning of Section 16(b) of the
Securities Exchange Act of 1934, claims based upon or attributable to directors
and officers gaining any personal profit or advantage to which such individuals
are not legally entitled, and for any claims brought about or attributable to
the dishonesty of an officer or director.

   It is recognized that the above-summarized provisions of the Company's By-
laws and the applicable Oklahoma General Corporation Law may be sufficiently
broad to indemnify officers, directors, and controlling persons of the Company
against liabilities arising under said Act.

   The Company and Western Resources, Inc. ("WRI") have entered into a
Registration Rights Agreement which provides for indemnification of the
Company's directors, officers, employees and controlling persons, if any, in
any offering or sale of shares of common stock, obtainable upon conversion of
the Series A Convertible Preferred Stock or Series B Convertible Preferred
Stock, against any claims (including amounts paid in settlement), or actions or
proceedings in respect thereof, arising out of or based upon an untrue
statement or alleged untrue statement of a material fact contained in such
registration statement or prospectus contained therein, or any document
incorporated by reference therein, or arising out of or based upon any omission
or alleged omission to state therein a material fact required to be stated or
necessary to make the statements therein not misleading, in each case only to
the extent that such untrue statement or alleged untrue statement or omission
or alleged omission was made in reliance upon and in conformity with written
information furnished to the Company by WRI or an agent or underwriter thereof
expressly for use therein.

Item 16. Exhibits.

<TABLE>
<CAPTION>
     Exhibit
     Number  Description
     ------- -----------
     <C>     <S>
      1.1    Form of Underwriting Agreement relating to Preferred Securities.*

      4.1    Form of Junior Subordinated Indenture among ONEOK, Inc. and
                   , as Trustee.

      4.2    Form of Supplemental Indenture to Junior Subordinated Indenture
             among ONEOK, Inc. and       , as Trustee.

      4.3(a) Form of Certificate of Trust of ONEOK Capital Trust I.

      4.3(b) Form of Certificate of Trust of ONEOK Capital Trust II.

      4.4(a) Form of Trust Agreement of ONEOK Capital Trust I.

      4.4(b) Form of Trust Agreement of ONEOK Capital Trust II.

      4.5    Form of Amended and Restated Trust Agreement (Agreements of ONEOK
             Capital Trust I and ONEOK Capital Trust II will be substantially
             identical except for names and dates).

      4.6    Form of Preferred Security of ONEOK Capital Trust I and ONEOK
             Capital Trust II (included in Exhibit 4.5 above) (Preferred
             Securities of ONEOK Capital Trust I and ONEOK Capital Trust II
             will be substantially identical except for names and dates).

      4.7    Form of Junior Subordinated Note (included in Exhibit 4.2 above).

      4.8    Form of Guarantee Agreement between ONEOK, Inc. and       , as
             trustee (Agreements relating to ONEOK Capital Trust I and ONEOK
             Capital Trust II will be substantially identical except for names
             and dates).

      4.9    Form of Agreement as to Expenses and Liabilities (included in
             Exhibit 4.5 above) (Agreements of ONEOK Capital Trust I and ONEOK
             Capital Trust II will be substantially identical except for names
             and dates).

      5.1    Opinion of Gable & Gotwals, relating to ONEOK, Inc.*
</TABLE>

                                      II-2
<PAGE>



<TABLE>
     <C>       <S>
      5.2(a)   Opinion of Richards, Layton & Finger, P.A., relating to ONEOK
               Capital Trust I.*

      5.2(b)   Opinion of Richards, Layton & Finger, P.A., relating to ONEOK
               Capital Trust II.*

      8.1      Opinion of Gable & Gotwals, counsel to ONEOK, Inc.*

     12.1      Computation of ratio of earnings to fixed charges.*

     12.2      Computation of ratio of earnings to combined fixed charges and
               preferred stock dividend requirements.*

     23.1      Consent of KPMG LLP.

     23.2      Consent of Arthur Andersen LLP.

     23.3      Consent of Gable & Gotwals (included in Exhibit 5.1 above).*

     23.4      Consent of Richards, Layton & Finger, P.A. (included in Exhibits
               5.2(a) and 5.2(b) above).*

     23.5      Consent of Gable & Gotwals (included in Exhibit 8.1 above).*

     24.1      Powers of Attorney (contained on the signature pages hereof).

     25.1      Form T-1 Statement of Eligibility under the Trust Indenture Act
               of 1939, as amended, of       , as Trustee for the Junior
               Subordinated Indenture.*

     25.2      Form T-1 Statement of Eligibility under the Trust Indenture Act
               of 1939, as amended, of       , as Property Trustee for the
               Amended and Restated Trust Agreement of ONEOK Capital Trust I.*

     25.3      Form T-1 Statement of Eligibility under the Trust Indenture Act
               of 1939, as amended, of       , as Trustee for the Guarantee
               Agreement relating to ONEOK Capital Trust I.*

     25.4      Form T-1 Statement of Eligibility under the Trust Indenture Act
               of 1939, as amended, of       , as Property Trustee for the
               Amended and Restated Trust Agreement of ONEOK Capital Trust II.*

     25.5      Form T-1 Statement of Eligibility under the Trust Indenture Act
               of 1939, as amended, of      , as Trustee for the Guarantee
               Agreement relating to ONEOK Capital Trust II.
</TABLE>
- --------
   *To be filed by amendment

Item 17. Undertakings.

   (a) Undertaking related to Rule 415 offering:

   The undersigned registrants hereby undertake:

     (1) To file, during any period in which offers or sales are being made,
  a post-effective amendment to this registration statement:

       (i) To include any prospectus required by Section 10(a)(3) of the
    Securities Act of 1933;

       (ii) To reflect in the prospectus any facts or events arising after
    the effective date of the registration statement (or the most recent
    post-effective amendment thereof) which, individually or in the
    aggregate, represent a fundamental change in the information set forth
    in the registration statement. Notwithstanding the foregoing, any
    increase or decrease in volume of securities offered (if the total
    dollar value of securities offered would not exceed that which was
    registered) and any deviation from the low or high end of the estimated
    maximum offering range may be reflected in the form of prospectus filed
    with the Commission pursuant to Rule 424(b) if, in the aggregate, the
    changes in volume and price represent no more than 20% change in the
    maximum aggregate offering price set forth in the "Calculation of
    Registration Fee" table in the effective registration statement.

       (iii) To include any material information with respect to the plan
    of distribution not previously disclosed in the registration statement
    or any material change to such information in the registration
    statement;

     Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply
  if the information required to be included in a post-effective amendment by
  those paragraphs is contained in periodic reports filed by the registrants
  pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of
  1934 that are incorporated by reference in the registration statement.

                                      II-3
<PAGE>

     (2) That, for the purpose of determining any liability under the
  Securities Act of 1933, each such post-effective amendment shall be deemed
  to be a new registration statement relating to the securities offered
  therein, and the offering of such securities at that time shall be deemed
  to be the initial bona fide offering thereof.

     (3) To remove from registration by means of a post-effective amendment
  any of the securities being registered which remain unsold at the
  termination of the offering.

   (b) Undertaking related to filings incorporating subsequent Securities
Exchange Act of 1934 documents by reference:

     The undersigned registrants hereby undertake that, for purposes of
  determining any liability under the Securities Act of 1933, each filing of
  the Company's annual report pursuant to Section 13(a) or Section 15(d) of
  the Securities Exchange Act of 1934 that is incorporated by reference in
  the registration statement shall be deemed to be a new registration
  statement relating to the securities offered therein, and the offering of
  such securities at that time shall be deemed to be the initial bona fide
  offering thereof.

   (c) Undertaking related to acceleration of effectiveness:

     Insofar as indemnification for liabilities arising under the Securities
  Act of 1933 may be permitted to directors, officers and controlling persons
  of the registrants pursuant to the foregoing provisions or otherwise, the
  registrants have been advised that in the opinion of the Securities and
  Exchange Commission such indemnification is against public policy as
  expressed in the Act and is, therefore, unenforceable. In the event that a
  claim for indemnification against such liabilities (other than the payment
  by the registrants of expenses incurred or paid by a director, officer or
  controlling person of the registrants in the successful defense of any
  action, suit or proceeding) is asserted by such director, officer or
  controlling person in connection with the securities being registered, the
  registrants will, unless in the opinion of their counsel the matter has
  been settled by controlling precedent, submit to a court of appropriate
  jurisdiction the question whether such indemnification by it is against
  public policy as expressed in the Act and will be governed by the final
  adjudication of such issue.

   (d) Undertakings related to Rule 430A offering:

     The undersigned registrants hereby undertake that:

       (1) For purposes of determining any liability under the Securities
    Act of 1933, the information omitted from the form of prospectus filed
    as part of this registration statement in reliance upon Rule 430A and
    contained in a form of prospectus filed by the registrants pursuant to
    Rule 424(b)(1) or (4) or 497(h) under the Act shall be deemed to be
    part of this registration statement as of the time it was declared
    effective.

       (2) For the purpose of determining any liability under the
    Securities Act of 1933, each post-effective amendment that contains a
    form of prospectus shall be deemed to be a new registration statement
    relating to the securities offered therein, and the offering of such
    securities at that time shall be deemed to be the initial bona fide
    offering thereof.

   (e) Undertaking related to qualification of trust indenture for delayed
offerings:

     The undersigned registrants hereby undertake to file applications for
  the purpose of determining the eligibility of the trustees to act under
  subsection (a) of Section 310 of the Trust Indenture Act in accordance with
  the rules and regulations prescribed by the Commission under Section
  305(b)(2) of the Act.

   (f) Undertaking related to equity offering of nonreporting registrants:

     The undersigned registrants hereby undertake to provide to the
  underwriter at the closing specified in the underwriting agreements,
  certificates in such denominations and registered in such names as required
  by the underwriter to permit prompt delivery to each purchaser.

                                      II-4
<PAGE>

                                   SIGNATURES

   Pursuant to the requirements of the Securities Act of 1933, the Registrant,
ONEOK, Inc., an Oklahoma corporation, certifies that it has reasonable grounds
to believe that it meets all of the requirements for filing on Form S-3 and has
duly caused this registration statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Tulsa, State of
Oklahoma, on the 12th day of July, 1999.

                                          ONEOK, Inc.

                                             /s/ James C. Kneale
                                          By: _________________________________
                                             James C. Kneale
                                             Vice President, Treasurer and
                                             Chief Financial Officer

   KNOW ALL MEN BY THESE PRESENT, that each person whose signature appears
immediately below constitutes and appoints James C. Kneale and John A.
Gaberino, Jr., and each of them, his or her true and lawful attorney-in-fact
and agent, with full power of substitution and resubstitution, for him or her
and in his or her name, place and stead, in any and all capacities, to sign any
and all amendments to this report, and to cause the same to be filed with the
Securities and Exchange Commission, granting unto said attorney-in-fact and
agents, and each of them, full power and authority to do and perform each and
every act and thing requisite and necessary to be done, as fully to all intents
and purposes as he or she might or could do in person, hereby ratifying and
confirming all that said attorney-in-fact and agents or any of them, or their
or his substitute or substitutes, may lawfully do or cause to be done by virtue
hereof.

   Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below by the following persons in the
capacities and on the dates indicated.


<TABLE>
<CAPTION>
             Signature                           Title                    Date
             ---------                           -----                    ----


<S>                                  <C>                           <C>
     /s/ Larry W. Brummett           Chairman of the Board, Chief    July 12, 1999
____________________________________  Executive Officer and
         Larry W. Brummett            Director (Principal
                                      Executive Officer)

         /s/ W. M. Bell              Director                        July 12, 1999
____________________________________
             W. M. Bell

       /s/ D. R. Cummings            Director                        July 12, 1999
____________________________________
           D. R. Cummings

       /s/ B. D. Epperson            Vice President, Controller      July 12, 1999
____________________________________  and Chief Accounting
           B. D. Epperson             Officer (Principal
                                      Accounting Officer)

         /s/ W. L. Ford              Director                        July 12, 1999
____________________________________
             W. L. Ford

        /s/ H. R. Fricke             Director                        July 12, 1999
____________________________________
            H. R. Fricke
</TABLE>

                                      II-5
<PAGE>



<TABLE>
<S>                                  <C>                           <C>
         /s/ D. L. Kyle              President, Chief Operating      July 12, 1999
____________________________________  Officer and Director
             D. L. Kyle

         /s/ D. T. Lake              Director                        July 12, 1999
____________________________________
             D. T. Lake

        /s/ B. H. Mackie             Director                        July 12, 1999
____________________________________
            B. H. Mackie

      /s/ James C. Kneale            Vice President, Treasurer       July 12, 1999
____________________________________  and Chief Financial Officer
          James C. Kneale             (Principal Financial
                                      Officer)

        /s/ J. D. Scott              Director                        July 12, 1999
____________________________________
            J. D. Scott

        /s/ S. L. Young              Director                        July 12, 1999
____________________________________
            S. L. Young

     /s/ Edwyna G. Anderson          Director                        July 12, 1999
____________________________________
         Edwyna G. Anderson

     /s/ Douglas Ann Newsom          Director                        July 12, 1999
____________________________________
         Douglas Ann Newsom

       /s/ Gary D. Parker            Director                        July 12, 1999
____________________________________
           Gary D. Parker
</TABLE>

                                      II-6
<PAGE>

   Pursuant to the requirements of the Securities Act of 1933, ONEOK Capital
Trust I certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Tulsa, State of Oklahoma, on the 12th day of
July, 1999.

                                          ONEOK Capital Trust I

                                          By: ONEOK, Inc.
                                             Depositor

                                             /s/ James C. Kneale
                                          By: _________________________________
                                             Name: James C. Kneale
                                             Title:   Vice President,
                                                   Treasurer and
                                                   Chief Financial Officer

                                      II-7
<PAGE>

   Pursuant to the requirements of the Securities Act of 1933, ONEOK Capital
Trust II certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in the City of Tulsa, State of Oklahoma, on the 12th day of
July, 1999.

                                          ONEOK Capital Trust II

                                          By: ONEOK, Inc.
                                             Depositor

                                            /s/ James C. Kneale
                                          By: _________________________________
                                             Name: James C. Kneale
                                             Title:   Vice President,
                                                   Treasurer and
                                                   Chief Financial Officer


                                      II-8
<PAGE>

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
  Exhibit
  Number   Description
  -------  -----------
 <C>       <S>                                                              <C>
  1.1      Form of Underwriting Agreement relating to Preferred
           Securities.*

  4.1      Form of Junior Subordinated Indenture among ONEOK, Inc. and
                 , as Trustee.

  4.2      Form of Supplemental Indenture to Junior Subordinated
           Indenture among ONEOK, Inc. and       , as Trustee.

  4.3(a)   Form of Certificate of Trust of ONEOK Capital Trust I.

  4.3(b)   Form of Certificate of Trust of ONEOK Capital Trust II.

  4.4(a)   Form of Trust Agreement of ONEOK Capital Trust I.

  4.4(b)   Form of Trust Agreement of ONEOK Capital Trust II.

  4.5      Form of Amended and Restated Trust Agreement (Agreements of
           ONEOK Capital Trust I and ONEOK Capital Trust II will be
           substantially identical except for names and dates).

  4.6      Form of Preferred Security of ONEOK Capital Trust I and ONEOK
           Capital Trust II (included in Exhibit 4.5 above) (Preferred
           Securities of ONEOK Capital Trust I and ONEOK Capital Trust II
           will be substantially identical except for names and dates).

  4.7      Form of Junior Subordinated Note (included in Exhibit 4.2
           above).

  4.8      Form of Guarantee Agreement between ONEOK, Inc. and       , as
           trustee (Agreements relating to ONEOK Capital Trust I and
           ONEOK Capital Trust II will be substantially identical except
           for names and dates).

  4.9      Form of Agreement as to Expenses and Liabilities (included in
           Exhibit 4.5 above) (Agreements of ONEOK Capital Trust I and
           ONEOK Capital Trust II will be substantially identical except
           for names and dates).

  5.1      Opinion of Gable & Gotwals, relating to ONEOK, Inc.*

  5.2(a)   Opinion of Richards, Layton & Finger, P.A., relating to ONEOK
           Capital Trust I.*

  5.2(b)   Opinion of Richards, Layton & Finger, P.A., relating to ONEOK
           Capital Trust II.*

  8.1      Opinion of Gable & Gotwals, counsel to ONEOK, Inc.*

 12.1      Computation of ratio of earnings to fixed charges.*

 12.2      Computation of ratio of earnings to combined fixed charges and
           preferred stock dividend requirements.*

 23.1      Consent of KPMG LLP.

 23.2      Consent of Arthur Andersen LLP.

 23.3      Consent of Gable & Gotwals (included in Exhibit 5.1 above).*

 23.4      Consent of Richards, Layton & Finger, P.A. (included in
           Exhibits 5.2(a) and 5.2(b) above).*

 23.5      Consent of Gable & Gotwals (included in Exhibit 8.1 above).*

 24.1      Powers of Attorney (contained on the signature pages hereof).

 25.1      Form T-1 Statement of Eligibility under the Trust Indenture
           Act of 1939, as amended, of       , as Trustee for the Junior
           Subordinated Indenture.*

 25.2      Form T-1 Statement of Eligibility under the Trust Indenture
           Act of 1939, as amended, of       , as Property Trustee for
           the Amended and Restated Trust Agreement of ONEOK Capital
           Trust I.*

 25.3      Form T-1 Statement of Eligibility under the Trust Indenture
           Act of 1939, as amended, of       , as Trustee for the
           Guarantee Agreement relating to ONEOK Capital Trust I.*

 25.4      Form T-1 Statement of Eligibility under the Trust Indenture
           Act of 1939, as amended, of       , as Property Trustee for
           the Amended and Restated Trust Agreement of ONEOK Capital
           Trust II.*

 25.5      Form T-1 Statement of Eligibility under the Trust Indenture
           Act of 1939, as amended, of      , as Trustee for the
           Guarantee Agreement relating to ONEOK Capital Trust II.
</TABLE>

<PAGE>

                                                                     EXHIBIT 4.1



                                  ONEOK, INC.

                                    Issuer


                                      and



                                 [__________]


                                    Trustee



                         JUNIOR SUBORDINATED INDENTURE


                        Dated as of [__________], 1999
<PAGE>

                                  ONEOK, INC.

     Reconciliation and tie between the Trust Indenture Act of 1939, as amended
(the "Trust Indenture Act") (including cross-references to provisions of
Sections 310 to and including 317 which, pursuant to Section 318(c) of the Trust
Indenture Act are a part of and govern the Junior Subordinated Indenture dated
as of [__________], 1999 (the "Junior Subordinated Indenture") whether or not
physically contained therein), and the Junior Subordinated Indenture.


              Trust Indenture
                Act Section                    Indenture Section

(S) 310 (a)(1), (2) and (5).................  6.9
(a) (3).....................................  Not Applicable
(a)(4)......................................  Not Applicable
(b).........................................  6.8
                                              6.10
(S) 311 (a).................................  6.13
(b).........................................  6.13
(b) (2).....................................  7.3(a)
(c).........................................  Not Applicable

(S) 312 (a).................................  7.1
                                              7.2(a)
(b).........................................  7.2(b)
(c).........................................  7.2(c)
(S) 313 (a).................................  7.3(a)
(b).........................................  7.3(a), (b)
(c).........................................  7.3(a), 7.3(b)
(d).........................................  7.3(c)
(S) 314 (a)(1), (2) and (3).................  7.4
(a)(4)......................................  10.5
(b).........................................  Not Applicable
(c)(1)......................................  1.2
(c)(2)......................................  1.2
(c)(3)......................................  Not Applicable
(d).........................................  Not Applicable
(e).........................................  1.2
(f).........................................  Not Applicable
(S) 315 (a).................................  6.1(a)
(b).........................................  6.2
                                              7.3(a), (b)
(c).........................................  6.1(b)
(d).........................................  6.1(c)
(d)(1)......................................  6.1(a)(1)
(d)(2)......................................  6.1(c)(2)
(d)(3)......................................  6.1(c)(3)
(e).........................................  5.14

<PAGE>

              Trust Indenture
                Act Section                       Indenture Section

(S) 316  (a)................................. 1.1
(a)(1)(A).................................... 5.12
(a)(1)(B).................................... 5.13
(a)(2)....................................... Not Applicable
(b).......................................... 5.8
(c).......................................... 1.4(f)
(S) 317  (a)(1).............................. 5.3
(a)(2)....................................... 5.4
(b).......................................... 10.3
(S) 318  (a)................................. 1.7


          [Note:  This reconciliation and tie is not and shall not, for any
          purpose, be deemed to be a part of the Junior Subordinated Indenture.]

<PAGE>


                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
<S>                                                                                                                    <C>
ARTICLE I   DEFINITIONS AND OTHER PROVISIONS
             OF GENERAL APPLICATION..................................................................................   1

            Section 1.1    Definitions...............................................................................   1
            Section 1.2    Compliance Certificate and Opinions.......................................................   9
            Section 1.3    Forms of Documents Delivered to Trustee...................................................   9
            Section 1.4    Acts of Holders...........................................................................  10
            Section 1.5    Notices, Etc. to the Trustee and the Company..............................................  12
            Section 1.6    Notice to Holders; Waiver.................................................................  12
            Section 1.7    Conflict with Trust Indenture Act.........................................................  12
            Section 1.8    Effect of Headings and Table of Contents..................................................  13
            Section 1.9    Successors and Assigns....................................................................  13
            Section 1.10   Separability Clause.......................................................................  13
            Section 1.11   Benefits of Indenture.....................................................................  13
            Section 1.12   Governing Law.............................................................................  13
            Section 1.13   Non-Business Days.........................................................................  13

ARTICLE II  SECURITY FORMS...........................................................................................  14

            Section 2.1    Forms Generally...........................................................................  14
            Section 2.2    Form of Face of Security..................................................................  14
            Section 2.3    Form of Reverse of Security...............................................................  17
            Section 2.4    Additional Provisions Required in Global Security.........................................  20
            Section 2.5    Form of Trustee's Certificate of Authentication...........................................  20

ARTICLE III THE SECURITIES...........................................................................................  20

            Section 3.1    Title and Terms...........................................................................  20
            Section 3.2    Denominations.............................................................................  23
            Section 3.3    Execution, Authentication, Delivery and Dating............................................  23
            Section 3.4    Temporary Securities......................................................................  24
            Section 3.5    Registration, Transfer and Exchange.......................................................  25
            Section 3.6    Mutilated, Destroyed, Lost and Stolen Securities..........................................  26
            Section 3.7    Payment of Interest; Interest Rights Preserved............................................  27
            Section 3.8    Persons Deemed Owners.....................................................................  28
            Section 3.9    Cancellation..............................................................................  28
            Section 3.10   Computation of Interest...................................................................  29
            Section 3.11   Deferrals of Interest Payment Dates.......................................................  29
            Section 3.12   Right of Set-Off..........................................................................  30
            Section 3.13   Agreed Tax Treatment......................................................................  30
            Section 3.14   Shortening or Extension of Stated Maturity................................................  30
            Section 3.15   CUSIP Numbers.............................................................................  30

ARTICLE IV  SATISFACTION AND DISCHARGE...............................................................................  31
</TABLE>
<PAGE>

<TABLE>
<S>                                                                                                                    <C>
            Section 4.1    Satisfaction and Discharge of Indenture..................................................   31
            Section 4.2    Application of Trust Money...............................................................   32
            Section 4.3    Satisfaction, Discharge and Defeasance of Securities of Any Series.......................   32

ARTICLE V   REMEDIES................................................................................................   34

            Section 5.1    Events of Default........................................................................   34
            Section 5.2    Acceleration of Maturity; Rescission and Annulment.......................................   35
            Section 5.3    Collection of Indebtedness and Suits for
                           Enforcement by Trustee...................................................................   36
            Section 5.4    Trustee May File Proofs of Claim.........................................................   36
            Section 5.5    Trustee May Enforce Claim Without Possession of Securities...............................   37
            Section 5.6    Application of Money Collected...........................................................   37
            Section 5.7    Limitation on Suits......................................................................   38
            Section 5.8    Unconditional Right of Holders to Receive Principal,
                           Premium and Interest; Direct Action by Holders
                           of Preferred Securities..................................................................   38
            Section 5.9    Restoration of Rights and Remedies.......................................................   39
            Section 5.10   Rights and Remedies Cumulative...........................................................   39
            Section 5.11   Delay or Omission Not Waiver.............................................................   39
            Section 5.12   Control by Holders.......................................................................   39
            Section 5.13   Waiver of Past Defaults..................................................................   40
            Section 5.14   Undertaking for Costs....................................................................   40
            Section 5.15   Waiver of Usury, Stay or Extension Laws..................................................   41

ARTICLE VI  THE TRUSTEE.............................................................................................   41

            Section 6.1    Certain Duties and Responsibilities......................................................   41
            Section 6.2    Notice of Defaults.......................................................................   42
            Section 6.3    Certain Rights of Trustee................................................................   42
            Section 6.4    Not Responsible for Recitals or Issuance of Securities...................................   43
            Section 6.5    May Hold Securities......................................................................   43
            Section 6.6    Money Held in Trust......................................................................   43
            Section 6.7    Compensation and Reimbursement...........................................................   44
            Section 6.8    Disqualification; Conflicting Interests..................................................   44
            Section 6.9    Corporate Trustee Required; Eligibility..................................................   44
            Section 6.10   Resignation and Removal; Appointment of Successor........................................   45
            Section 6.11   Acceptance of Appointment by Successor...................................................   46
            Section 6.12   Merger, Conversion, Consolidation or Succession to Business..............................   47
            Section 6.13   Preferential Collection of Claims Against Company........................................   47
            Section 6.14   Appointment of Authenticating Agent......................................................   48

ARTICLE VII HOLDER'S LISTS AND REPORTS BY TRUSTEE AND COMPANY.......................................................   49

            Section 7.1    Company to Furnish Trustee Names
                           and Addresses of Holders.................................................................   49
</TABLE>

                                     -ii-
<PAGE>

<TABLE>
<S>                                                                                                                   <C>
            Section 7.2    Preservation of Information, Communications to Holders....................................  49
            Section 7.3    Reports by Trustee........................................................................  50
            Section 7.4    Reports by the Company....................................................................  50

ARTICLE VIII  CONSOLIDATION, MERGER, CONVEYANCE,
               TRANSFER OR LEASE.....................................................................................  50

            Section 8.1    Company May Consolidate, Etc., Only on Certain Terms......................................  50
            Section 8.2    Successor Corporation Substituted.........................................................  51

ARTICLE IX  SUPPLEMENTAL INDENTURES..................................................................................  52

            Section 9.1    Supplemental Indentures without Consent of Holders........................................  52
            Section 9.2    Supplemental Indentures with Consent of Holders...........................................  53
            Section 9.3    Execution of Supplemental Indentures......................................................  54
            Section 9.4    Effect of Supplemental Indentures.........................................................  54
            Section 9.5    Conformity with Trust Indenture Act.......................................................  54
            Section 9.6    Reference in Securities to Supplemental Indentures........................................  55

ARTICLE X   COVENANTS................................................................................................  55

            Section 10.1   Payment of Principal, Premium and Interest................................................  55
            Section 10.2   Maintenance of Office or Agency...........................................................  55
            Section 10.3   Money or Security Payments to be Held in Trust............................................  56
            Section 10.4   Statement as to Compliance................................................................  57
            Section 10.5   Waiver of Certain Covenants...............................................................  57
            Section 10.6   Additional Sums...........................................................................  57
            Section 10.7   Additional Covenants......................................................................  58

ARTICLE XI  REDEMPTION OF SECURITIES.................................................................................  59

            Section 11.1   Applicability of This Article.............................................................  59
            Section 11.2   Election to Redeem; Notice to Trustee.....................................................  59
            Section 11.3   Selection of Securities to be Redeemed....................................................  59
            Section 11.4   Notice of Redemption......................................................................  60
            Section 11.5   Deposit of Redemption Price...............................................................  60
            Section 11.6   Payment of Securities Called for Redemption...............................................  60
            Section 11.7   Right of Redemption of Securities
                            Initially Issued to a ONEOK Capital Trust................................................  61

ARTICLE XII SINKING FUNDS............................................................................................  61

            Section 12.1   Applicability of Article..................................................................  61
            Section 12.2   Satisfaction of Sinking Fund Payments with Securities.....................................  62
            Section 12.3   Redemption of Securities for Sinking Fund.................................................  62

ARTICLE XIII SUBORDINATION OF SECURITIES.............................................................................  64
</TABLE>

                                     -iii-
<PAGE>

<TABLE>
          <S>                                                                                                        <C>
          Section 13.1   Securities Subordinate to Senior Debt.....................................................  64
          Section 13.2   Payment Over of Proceeds Upon Dissolution, Etc............................................  64
          Section 13.3   Prior Payment to Senior Debt Upon
                         Acceleration of Securities................................................................  65
          Section 13.4   No Payment When Senior Debt in Default....................................................  65
          Section 13.5   Payment Permitted If No Default...........................................................  66
          Section 13.6   Subrogation to Rights of Holders of Senior Debt...........................................  66
          Section 13.7   Provisions Solely to Define Relative Rights...............................................  67
          Section 13.8   Trustee to Effectuate Subordination.......................................................  67
          Section 13.9   No Waiver of Subordination Provisions.....................................................  67
          Section 13.10  Notice to Trustee.........................................................................  68
          Section 13.11  Reliance on Judicial Order or Certificate of
                         Liquidating Agent.........................................................................  68
          Section 13.12  Trustee Not Fiduciary for Holders of Senior Debt..........................................  69
          Section 13.13  Rights of Trustee as Holder of Senior Debt;
                         Preservation of Trustee 's Rights.........................................................  69
          Section 13.14  Article Applicable to Paying Agents.......................................................  69
          Section 13.15  Certain Conversions or Exchanges Deemed Payment...........................................  69
</TABLE>

                                     -iv-
<PAGE>

     JUNIOR SUBORDINATED INDENTURE dated as of [__________], 1999 (this
"Indenture") among ONEOK, INC., an Oklahoma corporation (the "Company") having
its principal office at 100 West Fifth Street, Tulsa, Oklahoma 74103, and
[__________], a national banking association duly organized and existing under
the laws of the United States, as Trustee (hereinafter called the "Trustee").


                            RECITALS OF THE COMPANY

     The Company has duly authorized the execution and delivery of this
Indenture (i) to provide for the issuance from time to time of its unsecured
junior subordinated notes in series (the "Securities") of substantially the
tenor hereinafter provided, including, without limitation, Securities issued to
evidence loans made to the Company of the proceeds from the issuance from time
to time by one or more business trusts (each, a "ONEOK Capital Trust" and,
collectively, the "ONEOK Capital Trusts") of preferred trust interests in such
ONEOK Capital Trusts (the "Preferred Securities") and common interests in such
ONEOK Capital Trusts (the "Common Securities" and, collectively with the
Preferred Securities, the "Trust Securities"), and (ii) to provide the terms and
conditions upon which the Securities are to be authenticated, issued and
delivered.

     All things necessary to make the Securities, when executed by the Company,
authenticated and delivered hereunder and duly issued by the Company, the valid
obligations of the Company, and to make this Indenture a valid agreement of the
Company, in accordance with their and its terms, have been done.

     NOW THEREFORE, THIS INDENTURE WITNESSETH:  For and in consideration of the
premises and the purchase of the Securities by the Holders thereof, it is
mutually covenanted and agreed, for the equal and proportionate benefit of all
Holders of Securities of any series thereof, as follows:


                                   ARTICLE I

     DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

     Section 1.1  Definitions.

     For all purposes of this Indenture (and any indenture supplemental hereto),
except as otherwise expressly provided or unless the context otherwise requires:

          (1)  The terms defined in this Article have the meanings assigned to
them in this Article and include the plural as well as the singular;

          (2)  All other terms used herein which are defined in the Trust
Indenture Act, either directly or by reference therein, have the meanings
assigned to them therein;

          (3)  All accounting terms not otherwise defined herein or in the Trust
Indenture Act, either directly or by reference therein, have the meanings
assigned to them in accordance with
<PAGE>

generally accepted accounting principles, and the term "generally accepted
accounting principles" with respect to any computation required or permitted
hereunder shall mean such accounting principles which are generally accepted at
the date or time of such computation; provided, that when two or more principles
are so generally accepted, it shall mean that set of principles consistent with
those in use by the Company; and

          (4)  The words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Indenture as a whole and not to any particular
Article, Section or other subdivision.

     "Act," when used with respect to any Holder, has the meaning specified in
Section 1.4 hereof.

     "Additional Interest" means the interest, if any, that shall accrue on any
interest on the Securities of any series the payment of which has not been made
on the applicable Interest Payment Date and which shall accrue at the rate per
annum specified or determined as specified in such Security.

     "Additional Sums" has the meaning specified in Section 10.6.

     "Additional Taxes" means the sum of any additional taxes, duties and other
governmental charges to which a ONEOK Capital Trust has become subject from time
to time as a result of a Tax Event.

     "Administrative Trustee" means, in respect of any ONEOK Capital Trust, each
Person identified as an "Administrative Trustee" in the related Trust Agreement,
solely in such Person's capacity as Administrative Trustee of such ONEOK Capital
Trust under such Trust Agreement and not in such Person's individual capacity,
or any successor administrative trustee appointed as therein provided.

     "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person; provided, however, no ONEOK Capital Trust to
                                    --------  -------
which Securities have been issued shall be deemed to be an Affiliate of the
Company.  For the purposes of this definition, "control" when used with respect
to any specified Person means the power to direct the management and policies of
such Person, directly or indirectly, whether through the ownership of voting
securities, by contract or otherwise; and the terms "controlling" and
"controlled" have meanings correlative to the foregoing.

     "Allocable Amounts," when used with respect to any Senior Debt, means all
amounts due or to become due on such Senior Debt less, if applicable, any amount
which would have been paid to, and retained by, the holders of such Senior Debt
(whether as a result of the receipt of payments by the holders of such Senior
Debt from the Company or any other obligor thereon or from any holders of, or
trustee in respect of, other indebtedness that is subordinate and junior in
right of payment to such Senior Debt pursuant to any provision of such
indebtedness for the payment over of amounts received on account of such
indebtedness to the holders of such Senior Debt or otherwise) but for the fact
that such Senior Debt is subordinate or junior in right of payment to (or
subject to a requirement that amounts received on such Senior Debt be paid over
to obligees on) trade accounts payable or accrued liabilities arising in the
ordinary course of business.

                                       2
<PAGE>

     "Authenticating Agent" means any Person authorized by the Trustee pursuant
to Section 6.14 to act on behalf of the Trustee to authenticate Securities of
one or more series.

     "Board of Directors" means either the board of directors of the Company or
any committee of that board duly authorized to act hereunder.

     "Board Resolution" means a copy of a resolution certified by the Secretary
or an Assistant Secretary of the Company to have been duly adopted by the Board
of Directors, or such committee of the Board of Directors or officers of the
Company to which authority to act on behalf of the Board of Directors has been
delegated, and to be in full force and effect on the date of such certification,
and delivered to the Trustee.

     "Business Day" means any day other than (i) a Saturday or Sunday, (ii) a
day on which banking institutions in The City of New York are authorized or
required by law or executive order to remain closed or (iii) a day on which the
Corporate Trust Office of the Trustee or, with respect to the Securities of a
series initially issued to a ONEOK Capital Trust, the principal office of the
Property Trustee under the related Trust Agreement, is closed for business.

     "Commission" means the Securities and Exchange Commission, as from time to
time constituted, created under the Exchange Act, or, if at any time after the
execution of this instrument such Commission is not existing and performing the
duties now assigned to it under the Trust Indenture Act, then the body
performing such duties on such date.

     "Common Securities" has the meaning specified in the first recital of this
Indenture.

     "Common Stock" means the common stock, without par value, of the Company.

     "Company" means the Person named as the "Company" in the first paragraph of
this Indenture until a successor corporation shall have become such pursuant to
the applicable provisions of this Indenture, and thereafter "Company" shall mean
any such successor corporation.

     "Company Request" and "Company Order" mean, respectively, the written
request or order signed in the name of the Company by the Chairman of the Board
of Directors, the Vice Chairman of the Board of Directors, its President or a
Vice President, and by its Treasurer, an Assistant Treasurer, its Secretary or
an Assistant Secretary, and delivered to the Trustee.

     "Corporate Trust Office" means the principal corporate trust office of the
Trustee at which, at any particular time, its corporate trust business shall be
administered, which office at the date hereof is located at [__________], except
for purposes of Section 10.2, if required with respect to a series of
Securities, such term shall mean the office or agency of the Trustee in the
Borough of Manhattan, The City of New York, which office at the date hereof is
located at [__________].

     "Corporation" includes a corporation, association, company, joint-stock
company or business trust.

     "Debt" means, with respect to any Person, whether recourse is to all or a
portion of the assets of such Person and whether or not contingent, (i) every
obligation of such Person for money

                                       3
<PAGE>

borrowed; (ii) every obligation of such Person evidenced by bonds, debentures,
notes or other similar instruments, including obligations incurred in connection
with the acquisition of property, assets or businesses; (iii) every
reimbursement obligation of such Person with respect to letters of credit,
bankers' acceptances or similar facilities issued for the account of such
Person; (iv) every obligation of such Person issued or assumed as the deferred
purchase price of property or services (but excluding trade accounts payable or
accrued liabilities arising in the ordinary course of business); (v) every
capital lease obligation of such Person; (vi) all indebtedness of such Person,
whether incurred on or prior to the date of this Indenture or thereafter
incurred, for claims in respect of derivative products, including interest rate,
foreign exchange rate and commodity forward contracts, options and swaps and
similar arrangements; and (vii) every obligation of the type referred to in
clauses (i) through (vi) of another Person and all dividends and operating lease
payments of another Person the payment of which, in either case, such Person has
guaranteed or is responsible or liable for, directly or indirectly, as obligor
or otherwise.

     "Defaulted Interest" has the meaning specified in Section 3.7.

     "Depositary" means, with respect to the Securities of any series issuable
or issued in whole or in part in the form of one or more Global Securities, the
Person designated as Depositary by the Company pursuant to Section 3.1 with
respect to such series (or any successor to the Depositary).

     "Discount Security" means any security which provides for an amount less
than the principal amount thereof to be due and payable upon a declaration of
acceleration of the Maturity thereof pursuant to Section 5.2.

     "Distributions," with respect to the Trust Securities issued by a ONEOK
Capital Trust, means amounts payable in respect of such Trust Securities as
provided in the related Trust Agreement and referred to therein as
"Distributions."

     "Dollar" means the currency of the United States of America that, at the
time of payment, is legal tender for the payment of public and private debts.

     "Event of Default," unless otherwise specified in the supplemental
indenture or Officers' Certificate creating a series of Securities, has the
meaning specified in Article V.

     "Exchange Act" means the Securities Exchange Act of 1934 and any statute
successor thereto, in each case as amended from time to time.

     "Expiration Date" has the meaning specified in Section 1.4.

     "Extension Period" has the meaning specified in Section 3.11.

     "Global Security" means a Security in the form prescribed in Section 2.4
evidencing all or part of a series of Securities, issued to the Depositary or
its nominee for such series, and registered in the name of such Depositary or
its nominee.

                                       4
<PAGE>

     "Guarantee Agreement" means the Guarantee Agreement between the Company and
the trustee certified therein, substantially in such form as may be specified as
contemplated by Section 3.1 with respect to the Securities of any series, in
each case as amended from time to time.

     "Holder" means a Person in whose name a Security is registered in the
Securities Register.

     "Indenture" means this instrument as originally executed or as it may from
time to time be supplemented or amended by one or more indentures supplemental
hereto entered into pursuant to the applicable provisions hereof and shall
include the terms of each particular series of Securities established as
contemplated by Section 3.1.

     "Interest Payment Date" means, as to each series of Securities, the Stated
Maturity of an installment of interest on such Securities.

     "Investment Company Act Event" means that a ONEOK Capital Trust shall have
received an Opinion of Counsel (as defined in the relevant Trust Agreement)
experienced in such matters to the effect that, as a result of the occurrence of
a change in law or regulation or a written change in the interpretation or
application of law or regulation by any legislative body, court, governmental
agency or regulatory authority, there is more than an insubstantial risk that
such ONEOK Capital Trust is or will be considered an "investment company" that
is required to be registered under the Investment Company Act of 1940, as
amended, which change becomes effective on or after the date of issuance of the
Preferred Securities of such ONEOK Capital Trust.

     "Junior Subordinated Payment" has the meaning specified in Section 13.2.

     "Maturity," when used with respect to any Security, means the date on which
the principal of such Security becomes due and payable as therein or herein
provided, whether at the Stated Maturity or by declaration of acceleration, call
for redemption or otherwise.

     "Moody's" means Moody's Investors Service, Inc.

     "Notice of Default" means a written notice of the kind specified in Section
5.1(3).

     "Officers' Certificate" means a certificate signed by the Chairman of the
Board of Directors, a Vice Chairman of the Board of Directors, the President or
a Vice President, and by the Treasurer, an Assistant Treasurer, the Secretary or
an Assistant Secretary of the Company, and delivered to the Trustee.

     "ONEOK Capital Guarantee" means the guarantee by the Company of
distributions on the Preferred Securities of a ONEOK Capital Trust to the extent
provided in the applicable Guarantee Agreement.

     "ONEOK Capital Trust" has the meaning specified in the first recital of
this Indenture.

     "Opinion of Counsel" means a written opinion of counsel, who may be counsel
for the Company and who shall be acceptable to the Trustee.

                                       5
<PAGE>

     "Original Issue Date" means the date of issuance specified as such in each
Security.

     "Outstanding" means, when used in reference to any Securities, as of the
date of determination, all Securities theretofore authenticated and delivered
under this Indenture, except:

     (i)       Securities theretofore canceled by the Trustee or delivered to
the Trustee for cancellation;

     (ii)      Securities for whose payment money in the necessary amount has
been theretofore deposited with the Trustee or any Paying Agent in trust for the
Holders of such Securities; and

     (ii)      Securities in substitution for or in lieu of which other
Securities have been authenticated and delivered or which have been paid
pursuant to Section 3.6, unless proof satisfactory to the Trustee is presented
that any such Securities are held by Holders in whose hands such Securities are
valid, binding and legal obligations of the Company; provided, however, that in
determining whether the Holders of the requisite principal amount of Outstanding
Securities have given any request, demand, authorization, direction, notice,
consent or waiver hereunder, Securities owned by the Company or any other
obligor upon the Securities or any Affiliate of the Company or such other
obligor shall be disregarded and deemed not to be Outstanding, except that, in
determining whether the Trustee shall be protected in relying upon any such
request, demand, authorization, direction, notice, consent or waiver, only
Securities which the Trustee knows to be so owned shall be so disregarded.
Securities so owned which have been pledged in good faith may be regarded as
Outstanding if the pledgee establishes to the satisfaction of the Trustee the
pledgee's right so to act with respect to such Securities and that the pledgee
is not the Company or any other obligor upon the Securities or any Affiliate of
the Company or such other obligor. Upon the written request of the Trustee, the
Company shall furnish to the Trustee promptly an Officers' Certificate listing
and identifying all Securities, if any, known by the Company to be owned or held
by or for the account of the Company, or any other obligor on the Securities or
any Affiliate of the Company or such obligor, and, subject to the provisions of
Section 6.1, the Trustee shall be entitled to accept such Officers' Certificate
as conclusive evidence of the facts therein set forth and of the fact that all
Securities not listed therein are Outstanding for the purpose of any such
determination.

     "Paying Agent" means the Trustee or any Person authorized by the Company to
pay the principal of or interest on any Securities on behalf of the Company.

     "Person" means any individual, corporation, partnership, joint venture,
trust, unincorporated organization or government or any agency or political
subdivision thereof.

     "Place of Payment" means, with respect to the Securities of any series, the
place or places where the principal of (and premium, if any) and interest on the
Securities of such series are payable pursuant to Sections 3.1 and 3.11.

     "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same debt as that evidenced by such
particular Security; and, for the purposes of this definition, any security
authenticated and delivered under Section 3.6 in lieu of a lost, destroyed or
stolen Security shall be deemed to evidence the same debt as the lost, destroyed
or stolen Security.

                                       6
<PAGE>

     "Preferred Securities" has the meaning specified in the first recital of
this Indenture.

     "Proceeding" has the meaning specified in Section 13.2.

     "Property Trustee" means, in respect of any ONEOK Capital Trust, the
commercial bank or trust company identified as the "Property Trustee" in the
related Trust Agreement, solely in its capacity as Property Trustee of such
ONEOK Capital Trust under such Trust Agreement and not in its individual
capacity, or its successor in interest in such capacity, or any successor
property trustee appointed as therein provided.

     "Redemption Date," when used with respect to any Security to be redeemed,
means the date fixed for such redemption by or pursuant to this Indenture.

     "Redemption Price," when used with respect to any Security to be redeemed,
means the price at which it is to be redeemed pursuant to this Indenture.

     "Regular Record Date" for the interest payable on any Interest Payment Date
with respect to the Securities of a series means, unless otherwise provided
pursuant to Section 3.1 with respect to Securities of a series, (i) in the case
of Securities of a series represented by one or more Global Securities, the
Business Day next preceding such Interest Payment Date and (ii) in the case of
Securities of a series not represented by one or more Global Securities, the
date which is fifteen days next preceding such Interest Payment Date (whether or
not a Business Day).

     "Responsible Officer," when used with respect to the Trustee, means any
officer of the Trustee assigned by the Trustee from time to time to administer
its corporate trust matters or any other officer to whom such a matter may be
referred.

     "Rights Plan" means a plan of the Company providing for the issuance by the
Company to all holders of its Common Stock of rights entitling the holders
thereof to subscribe for or purchase shares of Common Stock or any class or
series of preferred stock, which rights (i) are deemed to be transferred with
such shares of Common Stock, (ii) are not exercisable and (iii) are also issued
in respect of future issuances of Common Stock, in each case until the
occurrence of a specified event or events.

     "S&P" means Standard & Poor's Ratings Services, a division of The McGraw-
Hill Companies, Inc.

     "Securities" or "Security" means any debt securities or debt security, as
the case may be, authenticated and delivered under this Indenture.

     "Securities Register" and "Securities Registrar" have the respective
meanings specified in Section 3.5.

     "Senior Debt" means the principal of (and premium, if any) and interest, if
any (including interest accruing on or after the filing of any petition in
bankruptcy or for reorganization relating to the Company, whether or not such
claim for post-petition interest is allowed in such proceeding), on Debt of the
Company, whether incurred on or prior to the date of this Indenture or
thereafter

                                       7
<PAGE>

incurred, unless, in the instrument creating or evidencing the same or pursuant
to which the same is outstanding, it is provided that such obligations are not
superior in right of payment to the Securities or to other Debt which is pari
passu with, or subordinated to, the Securities, provided, however, that Senior
Debt shall not be deemed to include (a) any Debt of the Company which, when
incurred and without respect to any election under Section 1111(b) of the
Bankruptcy Reform Act of 1978, was without recourse to the Company, (b) any Debt
of the Company, to any of its Subsidiaries, (c) Debt to any employee of the
Company and (d) any Securities.

     "Special Event" means an Investment Company Act Event or a Tax Event.

     "Special Record Date" for the payment of any Defaulted Interest means a
date fixed by the Trustee pursuant to Section 3.7.

     "Stated Maturity" when used with respect to any Security or any installment
of principal thereof or interest thereon means the date specified pursuant to
the terms of such Security as the date on which the principal of such Security
or such installment of interest is due and payable, in the case of such
principal, as such date may be shortened or extended as provided pursuant to the
terms of such Security and this Indenture.

     "Subsidiary" means, with respect to any Person, a corporation more than 50%
of the outstanding voting stock of which is owned, directly or indirectly, by
such Person or by one or more other Subsidiaries, or by such Person and one or
more other Subsidiaries.  For purposes of this definition, "voting stock" means
stock which ordinarily has voting power for the election of directors, whether
at all times or only so long as no senior class of stock has such voting power
by reason of any contingency.

     "Tax Event" means the receipt by a ONEOK Capital Trust of an Opinion of
Counsel (as defined in the relevant Trust Agreement) experienced in such matters
to the effect that, as a result of any amendment to, or change (including any
announced prospective change) in, the laws (or any regulations thereunder) of
the United States or any political subdivision or taxing authority thereof or
therein, or as a result of any official administrative pronouncement or judicial
decision interpreting or applying such laws or regulations, which amendment or
change is effective or which pronouncement or decision is announced on or after
the date of issuance of the Preferred Securities of such ONEOK Capital Trust,
there is more than an insubstantial risk that (i) such ONEOK Capital Trust is,
or will be within 90 days of the date of such Opinion of Counsel, subject to
United States federal income tax with respect to income received or accrued on
the corresponding series of Securities issued by the Company to such ONEOK
Capital Trust, (ii) interest payable by the Company on such corresponding series
of Securities is not, or within 90 days of the date of such Opinion of Counsel,
will not be, deductible by the Company, in whole or in part, for United States
federal income tax purposes or (iii) such ONEOK Capital Trust is, or will be
within 90 days of the date of such Opinion of Counsel, subject to more than a de
minimis amount of other taxes, duties or other governmental charges.

     "Trust Agreement" means the Trust Agreement, as amended by the form of
Amended and Restated Trust Agreement, substantially in such form as may be
specified as contemplated by Section 3.1 with respect to the Securities of any
series, in each case as amended from time to time.

                                       8
<PAGE>

     "Trustee" means the Person named as the "Trustee" in the first paragraph of
this instrument until a successor Trustee shall have become such pursuant to the
applicable provisions of this Indenture, and thereafter "Trustee" shall mean or
include each Person who is then a Trustee hereunder and, if at any time there is
more than one such Person, "Trustee," as used with respect to the Securities of
any series, shall mean the Trustee with respect to Securities of that series.

     "Trust Indenture Act" means the Trust Indenture Act of 1939, as amended and
as in effect on the date of this Indenture, except as provided in Section 9.5.

     "Trust Securities" has the meaning specified in the first recital of this
Indenture.

     "Vice President," when used with respect to the Company or the Trustee, as
the case may be, means any duly appointed vice president, whether or not
designated by a number or a word or words added before or after the title "Vice
President."

     Section 1.2    Compliance Certificate and Opinions.

     Upon any application or request by the Company to the Trustee to take any
action under any provision of this Indenture, the Company shall furnish to the
Trustee an Officers' Certificate stating that all conditions precedent
(including covenants compliance with which constitutes a condition precedent),
if any, provided for in this Indenture relating to the proposed action have been
complied with and an Opinion of Counsel stating that in the opinion of such
counsel all such conditions precedent (including covenants compliance with which
constitutes a condition precedent), if any, have been complied with, except that
in the case of any such application or request as to which the furnishing of
such documents is specifically required by any provision of this Indenture
relating to such particular application or request, no additional certificate or
opinion need be furnished.

     Every certificate or opinion with respect to compliance with a condition or
covenant provided for in this Indenture (other than the certificates provided
pursuant to Section 10.5) shall include:

     (1)   a statement that each individual signing such certificate or
opinion has read such covenant or condition and the definitions herein relating
thereto;

     (2)   a brief statement as to the nature and scope of the examination or
investigation upon which the statements or opinions contained in such
certificate or opinion are based;

     (3)   a statement that, in the opinion of each such individual, he has made
such examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
complied with; and

     (4)   a statement as to whether, in the opinion of each such individual,
such condition or covenant has been complied with.

     Section 1.3    Forms of Documents Delivered to Trustee.

     In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion

                                       9
<PAGE>

of, only one such Person, or that they be so certified or covered by only one
document, but one such Person may certify or give an opinion with respect to
some matters and one or more other such Persons may certify or give an opinion
as to other matters, and any such Person may certify or give an opinion as to
such matters in one or several documents.

     Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representations by, counsel, unless such officer knows, or in the exercise of
reasonable care should know, that the certificate or opinion or representations
with respect to matters upon which his certificate or opinion is based are
erroneous. Any such certificate or Opinion of Counsel may be based, insofar as
it relates to factual matters, upon a certificate or opinion of, or
representations by, an officer or officers of the Company stating that the
information with respect to such factual matters is in the possession of the
Company, unless such counsel knows, or in the exercise of reasonable care should
know, that the certificate or opinion or representations with respect to such
matters are erroneous.

     Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.

     Section 1.4    Acts of Holders.

     (a)   Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Indenture to be given to or taken by
Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by an agent duly
appointed in writing; and, except as herein otherwise expressly provided, such
action shall become effective when such instrument or instruments is or are
delivered to the Trustee, and, where it is hereby expressly required, to the
Company. Such instrument or instruments (and the action embodied therein and
evidenced thereby) are herein sometimes referred to as the "Act" of the Holders
signing such instrument or instruments. Proof of execution of any such
instrument or of a writing appointing any such agent shall be sufficient for any
purpose of this Indenture and (subject to Section 6.1) conclusive in favor of
the Trustee and the Company, if made in the manner provided in this Section.

     (b)   The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by the certificate of any notary public or other officer authorized
by law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. Where such
execution is by a Person acting in other than his individual capacity, such
certificate or affidavit shall also constitute sufficient proof of this
authority.

     (c)   The fact and date of the execution by any Person of any such
instrument or writing, or the authority of the Person executing the same, may
also be proved in any other manner which the Trustee deems sufficient and in
accordance with such reasonable rules as the Trustee may determine.

     (d)   The ownership of Securities shall be proved by the Securities
Register.

                                       10
<PAGE>

     (e)  Any request, demand, authorization, direction, notice, consent, waiver
or other action by the Holder of any Security shall bind every future Holder of
the same Security and the Holder of every Security issued upon the transfer
thereof or in exchange therefor or in lieu thereof in respect of anything done
or suffered to be done by the Trustee or the Company in reliance thereon,
whether or not notation of such action is made upon such Security.

     (f)  The Company may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities of any series entitled to
give, make or take any request, demand, authorization, direction, notice,
consent, waiver or other action provided or permitted by this Indenture to be
given, made or taken by Holders of Securities of such series, provided that the
Company may not set a record date for, and the provisions of this paragraph
shall not apply with respect to, the giving or making of any notice,
declaration, request or direction referred to in the next paragraph. If any
record date is set pursuant to this paragraph, the Holders of Outstanding
Securities of the relevant series on such record date, and no other Holders,
shall be entitled to take the relevant action, whether or not such Holders
remain Holders after such record date, provided that no such action shall be
effective hereunder unless taken on or prior to the applicable Expiration Date
by Holders of the requisite principal amount of Outstanding Securities of such
series on such record date. Nothing in this paragraph shall be construed to
prevent the Company from setting a new record date for any action for which a
record date has previously been set pursuant to this paragraph (whereupon the
record date previously set shall automatically and with no action by any Person
be canceled and of no effect), and nothing in this paragraph shall be construed
to render ineffective any action taken by Holders of the requisite principal
amount of Outstanding Securities of the relevant series on the date such action
is taken. Promptly after any record date is set pursuant to this paragraph, the
Company, at its own expense, shall cause notice of such record date, the
proposed action by Holders and the applicable Expiration Date to be given to the
Trustee in writing and to each Holder of Securities of the relevant series in
the manner set forth in Section 1.6.

     The Trustee may set any day as a record date for the purpose of determining
the Holders of Outstanding Securities of any series entitled to join in the
giving or making of (i) any Notice of Default, (ii) any declaration of
acceleration referred to in Section 5.2, (iii) any request to institute
proceedings referred to in Section 5.7(2) or (iv) any direction referred to in
Section 5.12, in each case with respect to Securities of such series. If any
record date is set pursuant to this paragraph, the Holders of Outstanding
Securities of such series on such record date, and no other Holders, shall be
entitled to join in such notice, declaration, request or direction, whether or
not such Holders remain Holders after such record date, provided that no such
action shall be effective hereunder unless taken on or prior to the applicable
Expiration Date by Holders of the requisite principal amount of Outstanding
Securities of such series on such record date. Nothing in this paragraph shall
be construed to prevent the Trustee from setting a new record date for any
action for which a record date has previously been set pursuant to this
paragraph (whereupon the record date previously set shall automatically and with
no action by any Person be canceled and of no effect), and nothing in this
paragraph shall be construed to render ineffective any action taken by Holders
of the requisite principal amount of Outstanding Securities of the relevant
series on the date such action is taken. Promptly after any record date is set
pursuant to this paragraph, the Trustee, at the Company's expense, shall cause
notice of such record date, the proposed action by Holders and the applicable
Expiration Date to be given to the Company in writing and to each Holder of
Securities of the relevant series in the manner set forth in Section 1.6.

                                       11
<PAGE>

     With respect to any record date set pursuant to this Section, the party
hereto which sets such record date may designate any day as the "Expiration
Date" and from time to time may change the Expiration Date to any earlier or
later day, provided that no such change shall be effective unless notice of the
proposed new Expiration Date is given to the other party hereto in writing, and
to each Holder of Securities of the relevant series in the manner set forth in
Section 10.6, on or prior to the existing Expiration Date. If an Expiration Date
is not designated with respect to any record date set pursuant to this Section,
the party hereto which set such record date shall be deemed to have initially
designated the 180th day after such record date as the Expiration Date with
respect thereto, subject to its right to change the Expiration Date as provided
in this paragraph. Notwithstanding the foregoing, no Expiration Date shall be
later than the 180th day after the applicable record date.

     (g)  Without limiting the foregoing, a Holder entitled hereunder to take
any action hereunder with regard to any particular Security may do so with
regard to all or any part of the principal amount of such Security or by one or
more duly appointed agents, each of which may do so pursuant to such appointment
with regard to all or any part of such principal amount.

     Section 1.5  Notices, Etc. to the Trustee and the Company

     Any request, demand, authorization, direction, notice, consent, waiver or
Act of Holders or other document provided or permitted by this Indenture to be
made upon, given or furnished to, or filed with,

     (1)  the Trustee by any Holder, any holder of Preferred Securities or the
Company shall be sufficient for every purpose hereunder if made, given,
furnished or filed in writing to or with the Trustee at its Corporate Trust
Office, or

     (2)  the Company by the Trustee, any Holder or any holder of Preferred
Securities shall be sufficient for every purpose (except as otherwise provided
in Section 5.1) hereunder if in writing and mailed, first class, postage
prepaid, to the Company addressed to it at the address of its principal office
specified in the first paragraph of this instrument or at any other address
previously furnished in writing to the Trustee by the Company.

     Section 1.6  Notice to Holders; Waiver.

     Where this Indenture provides for notice to Holders of any event, such
notice shall be sufficiently given (unless otherwise herein expressly provided)
if in writing and mailed, first class postage prepaid, to each Holder affected
by such event, at the address of such Holder as it appears in the Securities
Register, not later than the latest date, and not earlier than the earliest
date, prescribed for the giving of such notice. In any case where notice to
Holders is given by mail, neither the failure to mail such notice, nor any
defect in any notice so mailed, to any particular Holder shall affect the
sufficiency of such notice with respect to other Holders. Where this Indenture
provides for notice in any manner, such notice may be waived in writing by the
Person entitled to receive such notice, either before or after the event, and
such waiver shall be the equivalent of such notice. Waivers of notice by Holders
shall be filed with the Trustee, but such filing shall not be a condition
precedent to the validity of any action taken in reliance upon such waiver.

                                       12
<PAGE>

     Section 1.7    Conflict with Trust Indenture Act.

     If any provision of this Indenture limits, qualifies or conflicts with the
duties imposed by any of Sections 310 to 317, inclusive, of the Trust Indenture
Act, through operation of Section 318(c) thereof, such imposed duties shall
control.

     Section 1.8    Effect of Headings and Table of Contents.

     The Article and Section headings herein and the Table of Contents are for
convenience only and shall not affect the construction hereof.

     Section 1.9    Successors and Assigns.

     All covenants and agreements in this Indenture by the Company shall bind
each of its successors and assigns, whether so expressed or not.

     Section 1.10   Separability Clause.

     In case any provision in this Indenture or in the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

     Section 1.11   Benefits of Indenture.

     Nothing in this Indenture or in the Securities, express or implied, shall
give to any Person, other than the parties hereto and their successors and
assigns, the holders of Senior Debt of the Company, the Holders of the
Securities and, to the extent expressly provided in Sections 5.2, 5.8, 5.9,
5.11, 5.13, 9.1 and 9.2, the holders of Preferred Securities, any benefit or any
legal or equitable right, remedy or claim under this Indenture.

     Section 1.12   Governing Law.

     This Indenture and the Securities shall be governed by and construed in
accordance with the laws of the State of New York without regard to the
principles of conflicts thereof.

     Section 1.13   Non-Business Days.

     In any case where any Interest Payment Date, Redemption Date or Stated
Maturity of any Security shall not be a Business Day, then (notwithstanding any
other provision of this Indenture or such Security) payment of interest or
principal (and premium, if any) need not be made on such date, but may be made
on the next succeeding Business Day (and no interest shall accrue for the period
from and after such Interest Payment Date, Redemption Date or Stated Maturity,
as the case may be, until such next succeeding Business Day except that, if such
Business Day is in the next succeeding calendar year, such payment shall be made
on the immediately preceding Business Day (in each case with the same force and
effect as if made on the Interest Payment Date or Redemption Date or at the
Stated Maturity).

                                       13
<PAGE>

                                  ARTICLE II

                                SECURITY FORMS

     Section 2.1  Forms Generally.

     The Securities of each series and the Trustee's certificate of
authentication shall be in substantially the forms set forth in this Article, or
in such other form or forms as shall be established by or pursuant to a Board
Resolution and as set forth in an Officers' Certificate or in one or more
indentures supplemental hereto, in each case with such appropriate insertions,
omissions, substitutions and other variations as are required or permitted by
this Indenture and may have such letters, numbers or other marks of
identification and such legends or endorsements placed thereon as may be
required to comply with applicable tax laws or the rules of any securities
exchange or as may, consistently herewith, be determined by the officers
executing such Securities, as evidenced by their execution of the Securities.
If the form of Securities of any series is established by action taken pursuant
to a Board Resolution, a copy of an appropriate record of such action shall be
certified by the Secretary or an Assistant Secretary of the Company and
delivered to the Trustee at or prior to the delivery of the Company Order
contemplated by Section 3.3 with respect to the authentication and delivery of
such Securities.

     The Trustee's certificates of authentication shall be substantially in the
form set forth in this Article.

     The definitive Securities shall be printed, lithographed or engraved or
produced by any combination of these methods, if required by any securities
exchange on which the Securities may be listed, on a steel engraved border or
steel engraved borders or may be produced in any other manner permitted by the
rules of any securities exchange on which the Securities may be listed, all as
determined by the officers executing such Securities, as evidenced by their
execution of such securities.

     Section 2.2  Form of Face of Security.

                                  ONEOK, INC.
                              (TITLE OF SECURITY)

No.                                                                  $__________

     ONEOK, INC., a corporation organized and existing under the laws of
Oklahoma (the "Company," which term includes any successor corporation under the
Indenture hereinafter referred to), for value received, hereby promises to pay
to _____________________, or registered assigns, the principal sum of
_______________ Dollars ($ ________) on _________ __, ____ [if applicable,
insert--;provided that the Company may (i) shorten the Stated Maturity of the
principal of this Security to a date not earlier than ___________ __, ____ and
(ii) extend the Stated Maturity of the principal of this Security at any time on
one or more occasions, subject to certain conditions specified in Section 3.14
of the Indenture, but in no event to a date later than __________].  The Company
further promises to pay interest on said principal sum from ____________ __,
____ or from the most recent interest payment date (each such date, an "Interest
Payment Date") on which interest has been paid or duly provided for, [monthly]
[quarterly] [semi-annually] [if applicable, insert--(subject to

                                       14
<PAGE>

deferral as set forth herein)] in arrears on _____________, ___________,
____________ and ___________ of each year, commencing _____________,
_____________, at the rate of ___% per annum, until the principal hereof shall
have become due and payable, [if applicable, insert--plus Additional Interest,
if any,] until the principal hereof is paid or duly provided for or made
available for payment [if applicable, insert--and on any overdue principal and
(without duplication and to the extent that payment of such interest is
enforceable under applicable law) on any overdue installment of interest at the
rate of ___% per annum, compounded [monthly] [quarterly] [semi-annually]]. The
amount of interest payable for any period shall be computed on the basis of
twelve 30-day months and a 360-day year. The amount of interest payable for any
partial period shall be computed on the basis of the number of days elapsed in a
360-day year of twelve 30-day months. In the event that any date on which
interest is payable on this Security is not a Business Day, then a payment of
the interest payable on such date will be made on the next succeeding day which
is a Business Day (and without any interest or other payment in respect of any
such delay), except that, if such Business Day is in the next succeeding
calendar year, such payment shall be made on the immediately preceding Business
Day, in each case with the same force and effect as if made on the date the
payment was originally payable. A "Business Day" shall mean any day other than
(i) a Saturday or Sunday, (ii) a day on which banking institutions in The City
of New York are authorized or required by law or executive order to remain
closed or (iii) a day on which the Corporate Trust Office of the Trustee [if
applicable, insert--, or the principal office of the Property Trustee under the
Trust Agreement hereinafter referred to for ONEOK Capital Trust________,] is
closed for business. The interest installment so payable, and punctually paid or
duly provided for, on any Interest Payment Date will, as provided in the
Indenture, be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on the Regular
Record Date for such interest installment, which shall be (i) in the case of
Securities represented by one or more Global Securities, the Business Day next
preceding such Interest Payment Date and (ii) in the case of Securities not
represented by one or more Global Securities, the date which is fifteen days
next preceding such Interest Payment Date (whether or not a Business Day). Any
such interest installment not so punctually paid or duly provided for shall
forthwith cease to be payable to the Holder on such Regular Record Date and may
either be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Trustee, notice whereof shall be given to Holders of Securities of this series
not less than 10 days prior to such Special Record Date, or be paid at any time
in any other lawful manner not inconsistent with the requirements of any
securities exchange on which the Securities of this series may be listed, and
upon such notice as may be required by such exchange, all as more fully provided
in said Indenture.

     [If applicable, insert--So long as no Event of Default has occurred and is
continuing, the Company shall have the right at any time during the term of this
Security to defer payment of interest on this Security, at any time or from time
to time, for up to ___ consecutive [monthly] [quarterly] [semi-annual] interest
payment periods with respect to each deferral period (each an "Extension
Period"), during which Extension Periods the Company shall have the right to
make partial payments of interest on any Interest Payment Date, and at the end
of which the Company shall pay all interest then accrued and unpaid (together
with Additional Interest thereon to the extent permitted by applicable law);
provided, however, that no Extension Period shall extend beyond the Stated
Maturity of the principal of this Security; provided, further, that during any
such Extension Period, the Company shall not, (i) declare or pay any dividends
or distributions or redeem, purchase, acquire or make a liquidation payment with
respect to, any of its capital stock or (ii) make any payment of

                                       15
<PAGE>

principal of or interest or premium, if any, on or repay, repurchase or redeem
any debt security issued by it that ranks pari passu with or junior in interest
to this Security or make any guarantee payments with respect to any guarantee by
the Company of any debt securities of any of its Subsidiaries if such guarantee
ranks pari passu with or junior in interest to this Security (other than (a)
dividends or distributions in Common Stock, (b) any declaration of a dividend in
connection with the implementation of a Rights Plan, the issuance of any Common
Stock or any class or series of preferred stock of the Company under any Rights
Plan or the repurchase of any rights distributed pursuant to a Rights Plan, and
(c) purchases of Common Stock related to the issuance of Common Stock under any
of the Company's benefit plans for their respective directors, officers or
employees). Prior to the termination of any such Extension Period, the Company
may further extend the interest payment period, provided that no Extension
Period shall ___ exceed consecutive [months] [quarters] [semi-annual periods] or
extend beyond the Stated Maturity of the principal of this Security. Upon the
termination of any such Extension Period and upon the payment of all accrued and
unpaid interest and any Additional Interest then due, the Company may elect to
begin a new Extension Period, subject to the above requirements. No interest
shall be due and payable during an Extension Period except at the end thereof.
The Company shall give the Holder of this Security and the Trustee notice of its
election to begin any Extension Period at least one Business Day prior to the
next succeeding Interest Payment Date on which interest on this Security would
be payable but for such deferral [if applicable, insert -- or, with respect to
the Securities issued to a ONEOK Capital Trust, so long as such Securities are
held by such ONEOK Capital Trust, prior to the earlier of (i) the next
succeeding date on which Distributions on the Preferred Securities of such ONEOK
Capital Trust would be payable but for such deferral or (ii) the date the
Administrative Trustee is required to give notice to any securities exchange or
other applicable self regulatory organization or to holders of such Preferred
Securities of the record date or the date such Distributions are payable, but in
any event not less than one Business Day prior to such record date].

     Payment of the principal of (and premium, if any) and interest on this
Security will be made at the office or agency of the Company maintained for that
purpose in the United States, in such coin or currency of the United States of
America as at the time of payment is legal tender for payment of public and
private debts [if applicable, insert--; provided, however, that at the option of
the Company payment of interest may be made (i) by check mailed to the address
of the Person entitled thereto as such address shall appear in the Securities
Register or (ii) by wire transfer in immediately available funds at such place
and to such account as may be designated by the Person entitled thereto as
specified in the Securities Register].

     The indebtedness evidenced by this Security is, to the extent provided in
the Indenture, subordinate and subject in right of payments to the prior payment
in full of all Senior Debt of the Company, and this Security is issued subject
to the provisions of the Indenture with respect thereto. Each Holder of this
Security, by accepting the same, (a) agrees to and shall be bound by such
provisions, (b) authorizes and directs the Trustee on his behalf to take such
actions as may be necessary or appropriate to effectuate the subordination so
provided and (c) appoints the Trustee his attorney-in-fact for any and all such
purposes. Each Holder hereof, by his acceptance hereof, waives all notice of the
acceptance of the subordination provisions contained herein and in the Indenture
by each holder of Senior Debt of the Company, whether now outstanding or
hereafter incurred, and waives reliance by each such holder upon said
provisions.

                                       16
<PAGE>

     Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal.

Dated:

                                        ONEOK, INC.


                                        By:_____________________________________
                                        [President or Vice President]
Attest:
_____________________________________
[Secretary or Assistant Secretary]

     SWORN TO ME and subscribed in my presence in the City of ___________, State
of _____________ this ___ day of __________, 19____.


                                        ________________________________________
                                        Notary Public

                                        Commission Expires: ____________________

                                        [NOTARIAL SEAL]

     Section 2.3  Form of Reverse of Security.

     This Security is one of a duly authorized issue of securities of the
Company (the "Securities"), issued and to be issued in one or more series under
the Junior Subordinated Indenture dated as of [__________], 1999 (the
"Indenture") between the Company and [______________________], as Trustee
(herein called the "Trustee," which term includes any successor trustee under
the Indenture), to which Indenture and all indentures supplemental thereto
reference is hereby made for a statement of the respective rights, limitations
of rights, duties and immunities thereunder of the Trustee, the Company and the
Holders of the Securities, and of the terms upon which the Securities are, and
are to be, authenticated and delivered. This Security is one of the series
designated on the face hereof [if applicable, insert--, limited in aggregate
principal amount to $___________].

     All terms used in this Security that are defined in the Indenture [if
applicable, insert -- or in the Amended and Restated Trust Agreement dated as of
____________ ____, ____, as amended (the "Trust Agreement"), for ONEOK Capital
Trust_______, among the Company, as Depositor, and the

                                       17
<PAGE>

Trustees named therein, shall have the meanings assigned to them in the
Indenture [if applicable, insert--or the Trust Agreement, as the case may be].

     [If applicable, insert--The Company may at any time, at its option, on or
after ________, ___, and subject to the terms and conditions of Article XI of
the Indenture, redeem this Security in whole at any time or in part from time to
time, without premium or penalty, at a redemption price equal to 100% of the
principal amount thereof plus accrued and unpaid interest [if applicable,
insert--,including Additional Interest, if any,] to the Redemption Date.]

     [If applicable, insert--Upon the occurrence and during the continuation of
a Special Event in respect of a ONEOK Capital Trust, the Company may, at its
option, at any time within 90 days of the occurrence of such Special Event
redeem this Security, in whole but not in part, subject to the provisions of
Section 11.7 and the other provisions of Article XI of the Indenture, at a
redemption price equal to 100% of the principal amount thereof plus accrued and
unpaid interest, including Additional Interest, if any, to the Redemption Date.]

     In the event of redemption of this Security in part only, a new Security or
Securities of this series for the unredeemed portion hereof will be issued in
the name of the Holder hereof upon the cancellation hereof.

     The Indenture contains provisions for satisfaction and discharge of the
entire indebtedness of this Security upon compliance by the Company with certain
conditions set forth in the Indenture.

     The Indenture permits, with certain exceptions as therein provided, the
Company and the Trustee at any time to enter into a supplemental indenture or
indentures for the purpose of modifying in any manner the rights and obligations
of the Company and of the Holders of the Securities, with the consent of the
Holders of not less than a majority in principal amount of the Outstanding
Securities of each series to be affected by such supplemental indenture.  The
Indenture also contains provisions permitting Holders of specified percentages
in principal amount of the Securities of each series at the time Outstanding, on
behalf of the Holders of all Securities of such series, to waive compliance by
the Company with certain provisions of the Indenture and certain past defaults
under the Indenture and their consequences.  Any such consent or waiver by the
Holder of this Security shall be conclusive and binding upon such Holder and
upon all future Holders of this Security and of any Security issued upon the
registration of transfer hereof or in exchange herefor or in lieu hereof,
whether or not notation of such consent or waiver is made upon this Security.

     [If the Security is not a Discount Security,--As provided in and subject to
the provisions of the Indenture, if an Event of Default with respect to the
Securities of this series at the time Outstanding occurs and is continuing, then
and in every such case the Trustee or the Holders of not less than 25% in
principal amount of the Outstanding Securities of this series may declare the
principal amount of all the Securities of this series to be due and payable
immediately, by a notice in writing to the Company (and to the Trustee if given
by Holders), provided that, in the case of the Securities of this series issued
to a ONEOK Capital Trust, if upon an Event of Default, the Trustee or the
Holders of not less than 25% in principal amount of the Outstanding Securities
of this series fail to declare the principal of all the Securities of this
series to be immediately due and payable, the holders of at least 25% in
aggregate Liquidation Amount of the Preferred Securities then outstanding of
such ONEOK Capital Trust shall have such right by a notice in writing to the
Company and the

                                       18
<PAGE>

Trustee; and upon any such declaration the principal amount of and the accrued
interest (including any Additional Interest) on all the Securities of this
series shall become immediately due and payable, provided that the payment of
principal and interest (including any Additional Interest) on such Securities
shall remain subordinated to the extent provided in Article XIII of the
Indenture.]

     [If the Security is a Discount Security,--As provided in and subject to the
provisions of the Indenture, if an Event of Default with respect to the
Securities of this series at the time Outstanding occurs and is continuing, then
and in every such case the Trustee or the Holders of not less than such portion
of the principal amount as may be specified in the terms of the Securities of
this series may declare an amount of principal of the Securities of this series
to be due and payable immediately, by a notice in writing to the Company (and to
the Trustee if given by Holders), provided that, in the case of the Securities
of this series issued to a ONEOK Capital Trust, if upon an Event of Default, the
Trustee or the Holders of not less than 25% in principal amount of the
Outstanding Securities of this series fails to declare the principal of all the
Securities of this series to be immediately due and payable, the holders of at
least 25% in aggregate Liquidation Amount of the Preferred Securities then
outstanding of such ONEOK Capital Trust shall have such right by a notice in
writing to the Company and the Trustee.  The amount of principal of the
Securities of this series that may be declared due and payable shall be equal
to--insert formula for determining the amount.  Upon any such declaration, such
amount of the principal of and the accrued interest (including any Additional
Interest) on all the Securities of this series shall become immediately due and
payable, provided that the payment of principal and interest (including any
Additional Interest) on such Securities shall remain subordinated to the extent
provided in Article XIII of the Indenture.  Upon payment (i) of the amount of
principal so declared due and payable and (ii) of interest on any overdue
principal and overdue interest (in each case to the extent that the payment of
such interest shall be legally enforceable), all of the Company's obligations in
respect of the payment of the principal of and interest, if any, on this
Security shall terminate.]

     No reference herein to the Indenture and no provision of this Security or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal of (and premium, if any) and
interest on this Security at the times, place and rate, and in the coin or
currency, herein prescribed.

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Security is registerable in the Securities Register,
upon surrender of this Security for registration of transfer at the office or
agency of the Company maintained under Section 10.2 of the Indenture duly
endorsed by, or accompanied by a written instrument of transfer in form
satisfactory to the Company and the Securities Registrar duly executed by, the
Holder hereof or his attorney duly authorized in writing, and thereupon one or
more new Securities of this series, of authorized denominations and for the same
aggregate principal amount, will be issued to the designated transferee or
transferees.  No service charge shall be made for any such registration of
transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith.

     Prior to due presentment of this Security for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not this Security be overdue, and none of the Company, the
Trustee or any such agent shall be affected by notice to the contrary.

                                       19
<PAGE>

     The Securities of this series are issuable only in registered form without
coupons in denominations of [$25] and any integral multiple thereof.  As
provided in the Indenture and subject to certain limitations therein set forth,
Securities of this series are exchangeable for a like aggregate principal amount
of Securities of such series of a different authorized denomination, as
requested by the Holder surrendering the same.

     The Company by its acceptance of this Security or a beneficial interest
therein, the Holder of, and any Person that acquires a beneficial interest in,
this Security agree that for United States federal, state and local tax purposes
it is intended that this Security constitute indebtedness.

     THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO CONFLICTS OF
LAWS PRINCIPLES THEREOF.

     Section 2.4  Additional Provisions Required in Global Security.

     Any Global Security issued hereunder shall, in addition to the provisions
contained in Sections 2.2 and 2.3, bear a legend in substantially the following
form:

     "This Security is a Global Security within the meaning of the Indenture
hereinafter referred to and is registered in the name of a Depositary or a
nominee of a Depositary.  This Security is exchangeable for Securities
registered in the name of a person other than the Depositary or its nominee only
in the limited circumstances described in the Indenture and may not be
transferred except as a whole by the Depositary to a nominee of the Depositary
or by a nominee of the Depositary to the Depositary or another nominee of the
Depositary."

     Section 2.5  Form of Trustee's Certificate of Authentication.

     This is one of the Securities referred to in the within-mentioned
Indenture.

Dated:

_______________________________
as Trustee


_______________________________
By:
     Authorized officer

                                       20
<PAGE>

                                  ARTICLE III

                                THE SECURITIES

     Section 3.1    Title and Terms.

     The aggregate principal amount of Securities which may be authenticated and
delivered under this Indenture is unlimited.

     The Securities may be issued in one or more series.  There shall be
established in or pursuant to a Board Resolution and set forth in an Officers'
Certificate, or established in one or more indentures supplemental hereto, prior
to the issuance of Securities of a series:

     (a)   the title of the Securities of such series, which shall distinguish
the Securities of the series from all other Securities;

     (b)   the limit, if any, upon the aggregate principal amount of the
Securities of such series which may be authenticated and delivered under this
Indenture (except for Securities authenticated and delivered upon registration
of transfer of, or in exchange for, or in lieu of, other Securities of the
series pursuant to Section 3.4, 3.5, 3.6, 9.6 or 11.6 and except for any
Securities which, pursuant to Section 3.3, are deemed never to have been
authenticated and delivered hereunder); provided, however, that the authorized
aggregate principal amount of such series may be increased above such amount by
a Board Resolution to such effect;

     (c)   the Stated Maturity or Maturities on which the principal of the
Securities of such series is payable or the method of determination thereof;

     (d)   the rate or rates, if any, at which the Securities of such series
shall bear interest, if any, the rate or rates and extent to which Additional
Interest, if any, shall be payable in respect of any Securities of such series,
the Interest Payment Dates on which such interest shall be payable, the right,
pursuant to Section 3.11 or as otherwise set forth therein, of the Company to
defer or extend an Interest Payment Date, and the Regular Record Date for the
interest payable on any Interest Payment Date or the method by which any of the
foregoing shall be determined;

     (e)   the place or places where the principal of (and premium, if any) and
interest on the Securities of such series shall be payable, the place or places
where the Securities of such series may be presented for registration of
transfer or exchange, and the place or places where notices and demands to or
upon the Company in respect of the Securities of such series may be made;

     (f)   the period or periods within or the date or dates on which, if any,
the price or prices at which and the terms and conditions upon which the
Securities of such series may be redeemed, in whole or in part, at the option of
the Company;

     (g)   the obligation or the right, if any, of the Company to redeem, repay
or purchase the Securities of such series pursuant to any sinking fund,
amortization or analogous provisions, and the period or periods within which,
the price or prices at which, the currency or currencies (including

                                       21
<PAGE>

currency unit or units) in which and the other terms and conditions upon which
Securities of the series shall be redeemed, repaid or purchased, in whole or in
part, pursuant to such obligation;

     (h)   the denominations in which any Securities of such series shall be
issuable, if other than denominations of [$25] and any integral multiple
thereof;

     (i)   if other than Dollars, the currency or currencies (including currency
unit or units) in which the principal of (and premium, if any) and interest, if
any, on the Securities of the series shall be payable, or in which the
Securities of the series shall be denominated;

     (j)   the additions, modifications or deletions, if any, in the Events of
Default or covenants of the Company set forth herein with respect to the
Securities of such series;

     (k)   if other than the principal amount thereof, the portion of the
principal amount of Securities of such series that shall be payable upon
declaration of acceleration of the Maturity thereof;

     (l)   the additions or changes, if any, to this Indenture with respect to
the Securities of such series as shall be necessary to permit or facilitate the
issuance of the Securities of such series in bearer form, registerable or not
registerable as to principal, and with or without interest coupons;

     (m)   any index or indices used to determine the amount of payments of
principal of and premium, if any, on the Securities of such series or the manner
in which such amounts will be determined;

     (n)   whether the Securities of the series, or any portion thereof, shall
initially be issuable in the form of a temporary Global Security representing
all or such portion of the Securities of such series and provisions for the
exchange of such temporary Global Security for definitive Securities of such
series;

     (o)   if applicable, that any Securities of the series shall be issuable in
whole or in part in the form of one or more Global Securities and, in such case,
the respective Depositaries for such Global Securities, the form of any legend
or legends which shall be borne by any such Global Security in addition to or in
lieu of that set forth in Section 2.4 and any circumstances in addition to or in
lieu of those set forth in Section 3.5 in which any such Global Security may be
exchanged in whole or in part for Securities registered, and any transfer of
such Global Security in whole or in part may be registered, in the name or names
of Persons other than the Depositary for such Global Security or a nominee
thereof;

     (p)   the appointment of any Paying Agent or Agents for the Securities of
such series;

     (q)   the terms of any right to convert or exchange Securities of such
series into any other securities or property of the Company, and the additions
or changes, if any, to this Indenture with respect to the Securities of such
series to permit or facilitate such conversion or exchange;

     (r)   the form or forms of the Trust Agreement, Amended and Restated Trust
Agreement and Guarantee Agreement;

                                       22
<PAGE>

     (s)   the relative degree, if any, to which the Securities of the series
shall be senior to or be subordinated to other series of Securities in right of
payment, whether such other series of Securities are Outstanding or not; and

     (t)   any other terms of the Securities of such series (which terms shall
not be inconsistent with the provisions of this Indenture).

     All Securities of any one series shall be substantially identical except as
to denomination and except as may otherwise be provided herein or in or pursuant
to such Board Resolution and set forth in such Officers' Certificate, or in any
such indenture supplemental hereto.

     If any of the terms of the series are established by action taken pursuant
to a Board Resolution, a copy of an appropriate record of such action shall be
certified by the Secretary or an Assistant Secretary and delivered to the
Trustee at or prior to the delivery of the Officers' Certificate of the Company
setting forth the terms of the series.

     The Securities shall be subordinated in right of payment to Senior Debt of
the Company as provided in Article XIII.

     Section 3.2    Denominations.

     The Securities of each series shall be in registered form without coupons
and shall be issuable in denominations of [$25] and any integral multiple
thereof, unless otherwise specified as contemplated by Section 3.1.

     Section 3.3    Execution, Authentication, Delivery and Dating.

     The Securities shall be executed on behalf of the Company by its President
or one of its Vice Presidents under its corporate seal reproduced or impressed
thereon and attested by its Secretary or one of its Assistant Secretaries.  The
signature of any of these officers on the Securities may be manual or facsimile.

     Securities bearing the manual or facsimile signatures of individuals who
were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Securities or did not
hold such offices at the date of such Securities.  At any time and from time to
time after the execution and delivery of this Indenture, the Company may deliver
Securities of any series executed by the Company to the Trustee for
authentication, together with a Company Order for the authentication and
delivery of such Securities, and the Trustee in accordance with the Company
Order shall authenticate and deliver such Securities.  If the form or terms of
the Securities of the series have been established by or pursuant to one or more
Board Resolutions as permitted by Sections 2.1 and 3.1, in authenticating such
Securities, and accepting the additional responsibilities under this Indenture
in relation to such Securities, the Trustee shall be entitled to receive, and
(subject to Section 6.1) shall be fully protected in relying upon, an Opinion of
Counsel stating,

                                       23
<PAGE>

          (1)  if the form of such Securities has been established by or
     pursuant to Board Resolution as permitted by Section 2.1, that such form
     has been establishe d in conformity with the provisions of this Indenture;

          (2)  if the terms of such Securities have been established by or
     pursuant to Board Resolution as permitted by Section 3.1, that such terms
     have been established in conformity with the provisions of this Indenture;
     and

          (3)  that such Securities, when authenticated and delivered by the
     Trustee and issued by the Company in the manner and subject to any
     conditions specified in such Opinion of Counsel, will constitute valid and
     legally binding obligations of the Company enforceable in accordance with
     their terms, subject to bankruptcy, insolvency, fraudulent transfer,
     reorganization, moratorium and similar laws of general applicability
     relating to or affecting creditors' rights and to general equity
     principles.

If such form or terms have been so established, the Trustee shall not be
required to authenticate such Securities if the issue of such Securities
pursuant to this Indenture will affect the Trustee's own rights, duties or
immunities under the Securities and this Indenture or otherwise in a manner
which is not reasonably acceptable to the Trustee.

     Notwithstanding the provisions of Section 3.1 and of the preceding
paragraph, if all Securities of a series are not to be originally issued at one
time, it shall not be necessary to deliver the Officers' Certificate of the
Company otherwise required pursuant to Section 3.1 or the Company Order and
Opinion of Counsel of the Company otherwise required pursuant to such preceding
paragraph at or prior to the authentication of each Security of such series if
such documents are delivered at or prior to the authentication upon original
issuance of the first Security of such series to be issued.

     Each Security shall be dated the date of its authentication.

     No Security shall be entitled to any benefit under this Indenture or be
valid or obligatory for any purpose, unless there appears on such Security a
certificate of authentication substantially in the form provided for herein
executed by the Trustee by the manual signature of one of its authorized
officers, and such certificate upon any Security shall be conclusive evidence,
and the only evidence, that such Security has been duly authenticated and
delivered hereunder.  Notwithstanding the foregoing, if any Security shall have
been authenticated and delivered hereunder but never issued and sold by the
Company, and the Company shall deliver such Security to the Trustee for
cancellation as provided in Section 3.9, for all purposes of this Indenture such
Security shall be deemed never to have been authenticated and delivered
hereunder and shall never be entitled to the benefits of this Indenture.

     Section 3.4    Temporary Securities.

     Pending the preparation of definitive Securities of any series, the Company
may execute, and upon Company Order the Trustee shall authenticate and deliver,
temporary Securities which are printed, lithographed, typewritten, mimeographed
or otherwise produced, in any denomination, substantially of the tenor of the
definitive Securities of such series in lieu of which they are issued and

                                       24
<PAGE>

with such appropriate insertions, omissions, substitutions and other variations
as the officers executing such Securities may determine, as evidenced by their
execution of such Securities.

     If temporary Securities of any series are issued, the Company will cause
definitive Securities of such series to be prepared without unreasonable delay.
After the preparation of definitive Securities, the temporary Securities shall
be exchangeable for definitive Securities upon surrender of the temporary
Securities at the office or agency of the Company designated for that purpose
without charge to the Holder.  Upon surrender for cancellation of any one or
more temporary Securities, the Company shall execute and the Trustee shall
authenticate and deliver in exchange therefor one or more definitive Securities
of the same series, of any authorized denominations having the same Original
Issue Date and Stated Maturity and having the same terms as such temporary
Securities. Until so exchanged, the temporary Securities of any series shall in
all respects be entitled to the same benefits under this Indenture as definitive
Securities of such series.

     Section 3.5    Registration, Transfer and Exchange.

     The Company shall cause to be kept at the Corporate Trust Office of the
Trustee a register in which, subject to such reasonable regulations as it may
prescribe, the Company shall provide for the registration of Securities and of
transfers of Securities.  Such register is herein sometimes referred to as the
"Securities Register." The Trustee is hereby appointed "Securities Registrar"
for the purpose of registering Securities and transfers of Securities as herein
provided.

     Upon surrender for registration of transfer of any Security at the office
or agency of the Company designated for that purpose the Company shall execute,
and the Trustee shall authenticate and deliver, in the name of the designated
transferee or transferees, one or more new Securities of the same series of any
authorized denominations, of a like aggregate principal amount, of the same
Original Issue Date and Stated Maturity and having the same terms.

     At the option of the Holder, Securities may be exchanged for other
Securities of the same series of any authorized denominations, of a like
aggregate principal amount, of the same Original Issue Date and Stated Maturity
and having the same terms, upon surrender of the Securities to be exchanged at
such office or agency.  Whenever any securities are so surrendered for exchange,
the Company shall execute, and the Trustee shall authenticate and deliver, the
Securities which the Holder making the exchange is entitled to receive.

     All Securities issued upon any transfer or exchange of Securities shall be
the valid obligations of the Company, evidencing the same debt, and entitled to
the same benefits under this Indenture, as the Securities surrendered upon such
transfer or exchange.

     Every Security presented or surrendered for transfer or exchange shall (if
so required by the Company or the Securities Registrar) be duly endorsed, or be
accompanied by a written instrument of transfer in form satisfactory to the
Company and the Securities Registrar, duly executed by the Holder thereof or his
attorney duly authorized in writing.

     No service charge shall be made to a Holder for any transfer or exchange of
Securities, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge that may be imposed in connection with any
transfer or exchange of Securities.

                                       25
<PAGE>

The provisions of Clauses (1), (2), (3) and (4) below shall apply only to
Global Securities:

          (1)  Each Global Security authenticated under this Indenture shall be
     registered in the name of the Depositary designated for such Global
     Security or a nominee thereof and delivered to such Depositary or a nominee
     thereof or custodian therefor, and each such Global Security shall
     constitute a single Security for all purposes of this Indenture.

          (2)  Notwithstanding any other provision in this Indenture, no Global
     Security may be exchanged in whole or in part for Securities registered,
     and no transfer of a Global Security in whole or in part may be registered,
     in the name of any Person other than the Depositary for such Global
     Security or a nominee thereof unless (A) such Depositary (i) has notified
     the Company that it is unwilling or unable to continue as Depositary for
     such Global Security or (ii) has ceased to be a clearing agency registered
     under the Exchange Act at a time when the Depositary is required to be so
     registered to act as depositary, in each case unless the Company has
     approved a successor Depositary within 90 days, (B) there shall have
     occurred and be continuing an Event of Default with respect to such Global
     Security, (C) the Company in its sole discretion determines that such
     Global Security will be so exchangeable or transferable or (D) there shall
     exist such circumstances, if any, in addition to or in lieu of the
     foregoing as have been specified for this purpose as contemplated by
     Section 3.1.

          (3)  Subject to Clause (2) above, any exchange of a Global Security
     for other Securities may be made in whole or in part, and all Securities
     issued in exchange for a Global Security or any portion thereof shall be
     registered in such names as the Depositary for such Global Security shall
     direct.

          (4)  Every Security authenticated and delivered upon registration of
     transfer of, or in exchange for or in lieu of, a Global Security or any
     portion thereof, whether pursuant to this Section, Section 3.4, 3.6, 9.6 or
     11.6 or otherwise, shall be authenticated and delivered in the form of, and
     shall be, a Global Security, unless such Security is registered in the name
     of a Person other than the Depositary for such Global Security or a nominee
     thereof.

     Neither the Company nor the Trustee shall be required, pursuant to the
provisions of this Section, (a) to issue, transfer or exchange any Security of
any series during a period beginning at the opening of business 15 days before
the day of selection for redemption of Securities pursuant to Article XI and
ending at the close of business on the day of mailing of notice of redemption or
(b) to transfer or exchange any Security so selected for redemption in whole or
in part, except, in the case of any Security to be redeemed in part, any portion
thereof not to be redeemed.

     Section 3.6    Mutilated, Destroyed, Lost and Stolen Securities.

     If any mutilated Security is surrendered to the Trustee together with such
security or indemnity as may be required by the Company or the Trustee to save
each of them harmless, the Company shall execute and the Trustee shall
authenticate and deliver in exchange therefor a new Security of the same issue
and series of like tenor and principal amount, having the same Original Issue
Date and Stated Maturity, and bearing a number not contemporaneously
outstanding.

                                       26
<PAGE>

     If there shall be delivered to the Company and to the Trustee (i) evidence
to their satisfaction of the destruction, loss or theft of any Security, and
(ii) such security or indemnity as may be required by them to save each of them
harmless, then, in the absence of notice to the Company, or the Trustee that
such Security has been acquired by a bona fide purchaser, the Company shall
execute and, upon the Company's request, the Trustee shall authenticate and
deliver, in lieu of any such destroyed, lost or stolen Security, a new Security
of the same issue and series of like tenor and principal amount, having the same
Original Issue Date and Stated Maturity as such destroyed, lost or stolen
Security, and bearing a number not contemporaneously outstanding.

     In case any such mutilated, destroyed, lost or stolen Security has become
or is about to become due and payable, the Company in its discretion may,
instead of issuing a new Security, pay such Security.

     Upon the issuance of any new Security under this Section, the Company may
require the payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed in relation thereto and any other expenses (including
the fees and expenses of the Trustee) connected therewith.

     Every new Security issued pursuant to this Section in lieu of any
destroyed, lost or stolen Security shall constitute an original additional
contractual obligation of the Company, whether or not the destroyed, lost or
stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all the benefits of this Indenture equally and proportionately with
any and all other Securities duly issued hereunder.

     The provisions of this Section are exclusive and shall preclude (to the
extent lawful) all other rights and remedies with respect to the replacement or
payment of mutilated, destroyed, lost or stolen Securities.

     Secton 3.7     Payment of Interest; Interest Rights Preserved.

     Interest on any Security of any series which is payable, and is punctually
paid or duly provided for, on any Interest Payment Date, shall be paid to the
Person in whose name that Security (or one or more Predecessor Securities) is
registered at the close of business on the Regular Record Date for such interest
in respect of Securities of such series, except that, unless otherwise provided
in the Securities of such series, interest payable on the Stated Maturity of the
principal of a Security shall be paid to the Person to whom principal is paid.
The initial payment of interest on any Security of any series which is issued
between a Regular Record Date and the related Interest Payment Date shall be
payable as provided in such Security or in the Board Resolution pursuant to
Section 3.1 with respect to the related series of Securities.

     Any interest on any Security which is payable, but is not timely paid or
duly provided for, on any Interest Payment Date for Securities of such series
(herein called "Defaulted Interest"), shall forthwith cease to be payable to the
registered Holder on the relevant Regular Record Date by virtue of having been
such Holder, and such Defaulted Interest may be paid by the Company, at its
election in each case, as provided in Clause (1) or (2) below:

                                       27
<PAGE>

     (1)   The Company may elect to make payment of any Defaulted Interest to
the Persons in whose names the Securities of such series in respect of which
interest is in default (or their respective Predecessor Securities) are
registered at the close of business on a Special Record Date for the payment of
such Defaulted Interest, which shall be fixed in the following manner. The
Company shall notify the Trustee in writing of the amount of Defaulted Interest
proposed to be paid on each Security and the date of the proposed payment, and
at the same time the Company shall deposit with the Trustee an amount of money
equal to the aggregate amount proposed to be paid in respect of such Defaulted
Interest or shall make arrangements satisfactory to the Trustee for such deposit
prior to the date of the proposed payment, such money when deposited to be held
in trust for the benefit of the Persons entitled to such Defaulted Interest as
in this Clause provided. Thereupon the Trustee shall fix a Special Record Date
for the payment of such Defaulted Interest which shall be not more than 15 days
and not less than 10 days prior to the date of the proposed payment and not less
than 10 days after the receipt by the Trustee of the notice of the proposed
payment. The Trustee shall promptly notify the Company of such Special Record
Date and, in the name and at the expense of the Company, shall cause notice of
the proposed payment of such Defaulted Interest and the Special Record Date
therefor to be mailed, first class, postage prepaid, to each Holder of a
Security of such series at the address of such Holder as it appears in the
Securities Register not less than 10 days prior to such Special Record Date. The
Trustee may, in its discretion, in the name and at the expense of the Company,
cause a similar notice to be published at least once in a newspaper, customarily
published in the English language on each Business Day and of general
circulation in the Borough of Manhattan, The City of New York, but such
publication shall not be a condition precedent to the establishment of such
Special Record Date. Notice of the proposed payment of such Defaulted Interest
and the Special Record Date therefor having been mailed as aforesaid, such
Defaulted Interest shall be paid to the Persons in whose names the Securities of
such series (or their respective Predecessor Securities) are registered on such
Special Record Date and shall no longer be payable pursuant to the following
Clause (2).

     (2)   The Company may make payment of any Defaulted Interest in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities of the series in respect of which interest is in default
may be listed and, upon such notice as may be required by such exchange (or by
the Trustee if the Securities are not listed), if after notice given by the
Company to the Trustee of the proposed payment pursuant to this Clause, such
payment shall be deemed practicable by the Trustee.

     Subject to the foregoing provisions of this Section, each Security
delivered under this Indenture upon transfer of or in exchange for or in lieu of
any other Security shall carry the rights to interest accrued and unpaid, and to
accrue, which were carried by such other Security.

     Section 3.8    Persons Deemed Owners.

     The Company, the Trustee and any agent of the Company or the Trustee may
treat the Person in whose name any Security is registered as the owner of such
Security for the purpose of receiving payment of principal of and (subject to
Section 3.7) any interest on such Security and for all other purposes
whatsoever, whether or not such Security be overdue, and none of the Company,
the Trustee or any agent of the Company or the Trustee shall be affected by
notice to the contrary.

     Section 3.9    Cancellation.

                                       28
<PAGE>

     All Securities surrendered for payment, redemption, transfer or exchange
shall, if surrendered to any Person other than the Trustee, be delivered to the
Trustee, and any such Securities and Securities surrendered directly to the
Trustee for any such purpose shall be promptly canceled by it. The Company may
at any time deliver to the Trustee for cancellation any Securities previously
authenticated and delivered hereunder which the Company may have acquired in any
manner whatsoever, and all Securities so delivered shall be promptly canceled by
the Trustee.  No Securities shall be authenticated in lieu of or in exchange for
any Securities canceled as provided in this Section, except as expressly
permitted by this Indenture.  All canceled Securities shall be destroyed by the
Trustee and the Trustee shall, if requested, deliver to the Company a
certificate of such destruction.

     Section 3.10   Computation of Interest.

     Except as otherwise specified as contemplated by Section 3.1 for Securities
of any series, interest on the Securities of each series for any period shall be
computed on the basis of a 360-day year of twelve 30-day months and interest on
the Securities of each series for any partial period shall be computed on the
basis of the number of days elapsed in a 360-day year of twelve 30-day months.

     Section 3.11   Deferrals of Interest Payment Dates.

     If specified as contemplated by Section 2.1 or Section 3.1 with respect to
the Securities of a particular series, so long as no Event of Default has
occurred and is continuing, the Company shall have the right, at any time during
the term of such series, from time to time to defer the payment of interest on
such Securities for such period or periods as may be specified as contemplated
by Section 3.1 (each, an "Extension Period"), during which Extension Periods the
Company shall have the right to make partial payments of interest on any
Interest Payment Date.  No Extension Period shall end on a date other than an
Interest Payment Date.  At the end of any such Extension Period, the Company
shall pay all interest then accrued and unpaid on the Securities (together with
Additional Interest thereon, if any, at the rate specified for the Securities of
such series to the extent permitted by applicable law); provided, however, that
no Extension Period shall extend beyond the Stated Maturity of the principal of
the Securities of such series; provided, further, that during any such Extension
Period, the Company shall not, (i) declare or pay any dividends or distributions
on, or redeem, purchase, acquire or make a liquidation payment with respect to,
any of its capital stock, or (ii) make any payment of principal of or interest
or premium, if any, on or repay, repurchase or redeem any debt security issued
by it that ranks pari passu with or junior in interest to the Securities of such
series or make any guarantee payments with respect to any guarantee by the
Company of the debt securities of any of its Subsidiaries that by their terms
rank pari passu with or junior in interest to the securities of such series
(other than (a) dividends or distributions in Common Stock, (b) any declaration
of a dividend in connection with the implementation of a Rights Plan, the
issuance of any Common Stock or any class or series of preferred stock of the
Company under any Rights Plan or the repurchase of any rights distributed
pursuant to a Rights Plan, and (c) purchases of Common Stock related to the
issuance of Common Stock under any of the Company's benefit plans for their
respective directors, officers or employees).  Prior to the termination of any
such Extension Period, the Company may further extend the interest payment
period, provided that no Extension Period shall exceed the period or periods
specified in such Securities or extend beyond the Stated Maturity of the
principal of such Securities.  Upon termination of any Extension Period and upon
the payment of all accrued and unpaid interest and any Additional Interest then
due on any Interest Payment Date, the Company may elect to begin a new Extension
Period, subject to the above requirements.  No interest

                                       29
<PAGE>

shall be due and payable during an Extension Period, except at the end thereof.
The Company shall give the Holders of the Securities of such series and the
Trustee notice of its election to begin or extend any such Extension Period at
least one Business Day prior to the next succeeding Interest Payment Date on
which interest on Securities of such series would be payable but for such
deferral or, with respect to the Securities of a series issued to a ONEOK
Capital Trust, so long as such Securities are held by such ONEOK Capital Trust,
prior to the earlier of (i) the next succeeding date on which Distributions on
the Preferred Securities of such ONEOK Capital Trust would be payable but for
such deferral or (ii) the date the Administrative Trustee of such ONEOK Capital
Trust are required to give notice to any securities exchange or other applicable
self regulatory organization or to holders of such Preferred Securities of the
record date or the date such Distributions are payable, but in any event not
less than one Business Day prior to such record date.

     The Trustee shall promptly give notice of the Company's election to begin
any such Extension Period to the Holders of the Outstanding Securities of such
series.

     Section 3.12   Right of Set-Off.

     With respect to the Securities of a series issued to a ONEOK Capital Trust,
notwithstanding anything to the contrary in the Indenture, the Company shall
have the right to set-off any payment it is otherwise required to make
thereunder in respect of any such Security to the extent the Company has
theretofore made, or is concurrently on the date of such payment making, a
payment with respect to the ONEOK Capital Guarantee relating to such Security,
or the Company has theretofore made, or is concurrently on the date of such
payment making, a payment under Section 5.8 of the Indenture.

     Section 3.13   Agreed Tax Treatment.

     Each Security issued hereunder shall provide that the Company and, by its
acceptance of a Security or a beneficial interest therein, the Holder of, and
any Person that acquires a beneficial interest in, such Security agree that for
United States federal, state and local tax purposes it is intended that such
Security constitute indebtedness.

     Section 3.14   Shortening or Extension of Stated Maturity.

     If specified as contemplated by Section 2.1 or Section 3.1 with respect to
the Securities of a particular series, the Company shall have the right to (i)
shorten the Stated Maturity of the principal of the Securities of such series at
any time to any date not earlier than the first date on which the Company has
the right to redeem the Securities of such series, and (ii) extend the Stated
Maturity of the principal of the Securities of such series at any time at its
election for one or more periods, but in no event to a date later than the
[49TH] anniversary of the first Interest Payment Date following the Original
Issue Date of the Securities of such series; provided that, if the Company
elects to exercise its right to extend the Stated Maturity of the principal of
the Securities of such series pursuant to clause (ii), above, at the time such
election is made and at the time of extension (A) the Company is not in
bankruptcy, otherwise insolvent or in liquidation, (B) the Company is not in
default in the payment of any interest or principal on such Securities, (C) in
the case of any series of Securities issued to a ONEOK Capital Trust, such ONEOK
Capital Trust is not in arrears on payments of Distributions on the Preferred
Securities issued by such ONEOK Capital Trust and no deferred Distributions are
accumulated and (D) such Securities are rated not less than BBB- by S&P or Baa3

                                       30
<PAGE>

by Moody's, or the equivalent by any other nationally recognized statistical
orating organization.  In the event the Company elects to shorten or extend the
Stated Maturity of the Securities of a particular series, it shall give notice
to the Trustee, no less than 30 and no more than 60 days prior to the
effectiveness thereof.  The Trustee shall give notice of such shortening or
extension to the Holders promptly upon receipt.

     Section 3.15   CUSIP Numbers.

     The Company in issuing the Securities may use "CUSIP" numbers (if then
generally in use), and, if so, the Trustee shall use "CUSIP" numbers in notices
of redemption as a convenience to Holders; provided that any such notice may
state that no representation is made as to the correctness of such numbers
either as printed on the Securities or as contained in any notice of a
redemption and that reliance may be placed only on the other identification
numbers printed on the Securities, and any such redemption shall not be affected
by any defect in or omission of such "CUSIP" numbers.

                                  ARTICLE IV

                          SATISFACTION AND DISCHARGE

     Section 4.1    Satisfaction and Discharge of Indenture.

     This Indenture shall, upon Company Request, cease to be of further effect
(except as to any surviving rights of registration of transfer or exchange of
Securities herein expressly provided for and as otherwise provided in this
Section 4.1) and the Trustee, on demand of and at the expense of the Company,
shall execute proper instruments acknowledging satisfaction and discharge of
this Indenture, when

     (1)   either

     (A)   all Securities theretofore authenticated and delivered (other than
(i) Securities which have been destroyed, lost or stolen and which have been
replaced or paid as provided in Section 3.6 and (ii) Securities for whose
payment money has theretofore been deposited in trust or segregated and held in
trust by the Company and thereafter repaid to the Company or discharged from
such trust, as provided in Section 10.3) have been delivered to the Trustee for
cancellation; or

     (B)   all such Securities not theretofore delivered to the Trustee for
cancellation

           (i)      have become due and payable, or

           (ii)     will become due and payable at their Stated Maturity within
                    one year of the date of deposit, or

           (iii)    are to be called for redemption within one year under
                    arrangements satisfactory to the Trustee for the giving of
                    notice of redemption by the Trustee in the name, and at the
                    expense, of the Company,

                                       31
<PAGE>

                    and the Company, in the case of Clause (B) (i), (ii) or
                    (iii) above, has deposited or caused to be deposited with
                    the Trustee as trust funds in trust for such purpose an
                    amount in the currency or currencies in which the Securities
                    of such series are payable sufficient to pay and discharge
                    the entire indebtedness on such Securities not theretofore
                    delivered to the Trustee for cancellation, for principal
                    (and premium, if any) and interest (including any Additional
                    Interest) to the date of such deposit (in the case of
                    Securities which have become due and payable) or to the
                    Stated Maturity or Redemption Date, as the case may be; and


     (2)   the Company has paid or caused to be paid all other sums payable
hereunder by the Company; and

     (3)   the Company has delivered to the Trustee an Officers' Certificate and
an Opinion of Counsel each stating that all conditions precedent herein provided
for relating to the satisfaction and discharge of this Indenture have been
complied with.

Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 6.7, the obligations of
the Trustee to any Authenticating Agent under Section 6.14 and, if money shall
have been deposited with the Trustee pursuant to subclause (B) of clause (1) of
this Section, the obligations of the Trustee under Section 4.2 and the last
paragraph of Section 10.3 shall survive.

     Section 4.2    Application of Trust Money.

     Subject to the provisions of the last paragraph of Section 10.3, all money
deposited with the Trustee pursuant to Section 4.1 shall be held in trust and
applied by the Trustee, in accordance with the provisions of the Securities and
this Indenture, to the payment, either directly or through any Paying Agent
(including the Company acting as its own Paying Agent) as the Trustee may
determine, to the Persons entitled thereto, of the principal (and premium, if
any) and interest for the payment of which such money or obligations have been
deposited with or received by the Trustee.

     Section 4.3    Satisfaction, Discharge and Defeasance of Securities of Any
Series.

     Unless otherwise provided in the Board Resolution adopted pursuant to
Section 3.1  or an indenture supplemental hereto establishing the terms of the
Securities of any series, the Company shall be deemed to have paid and
discharged the entire indebtedness on all the Outstanding Securities of any such
series and the Trustee, at the expense of the Company, shall execute proper
instruments acknowledging satisfaction and discharge of such indebtedness, when

     (1)   with respect to all Outstanding Securities of such series,

           (A)  the Company has irrevocably deposited or caused to be
     irrevocably deposited with the Trustee as trust funds in trust for such
     purpose an amount sufficient to pay and discharge the entire indebtedness
     on all Outstanding Securities of such series for principal (and premium, if
     any) and interest (including any Additional Interest) to the Stated
     Maturity or any Redemption Date as contemplated by the penultimate
     paragraph of this Section 4.3, as the case may be; or

                                       32
<PAGE>

           (B)  the Company has irrevocably deposited or caused to be
     irrevocably deposited with the Trustee as obligations in trust for such
     purpose an amount of trust funds as will, in the written opinion of
     independent public accountants delivered to the Trustee, together with
     predetermined and certain income to accrue thereon, without consideration
     of any reinvestment thereof, be sufficient to pay and discharge when due
     the entire indebtedness on all Outstanding Securities of such series for
     principal (and premium, if any) and interest (including any Additional
     Interest) to the Stated Maturity or any Redemption Date as contemplated by
     the penultimate paragraph of this Section 4.3, as the case may be;

     (2)   the Company has paid or caused to be paid all other sums payable with
respect to the Outstanding Securities of such series;

     (3)   the Company has delivered to the Trustee an Officers' Certificate and
     an Opinion of Counsel, each stating that all conditions precedent herein
     provided for relating to the satisfaction and discharge of the entire
     indebtedness on all Outstanding Securities of any such series have been
     complied with; and

     (4)   the Company has also delivered to the Trustee, together with such
     Officers' Certificate, either:

           (A) an instrument wherein the Company, notwithstanding the
     satisfaction and discharge of its indebtedness in respect of the
     Outstanding Securities of such series, shall assume the obligation (which
     shall be absolute and unconditional) to irrevocably deposit with the
     Trustee such additional sums of money, if any, or additional amounts
     (meeting the requirements of subsection (1) of this Section 4.3), if any,
     or any combination thereof, at such time or times, as shall be necessary,
     together with the money and/or amounts theretofore so deposited, to pay
     when due the principal of and interest due and to become due on such
     Outstanding Securities of such series or portions thereof, all in
     accordance with and subject to the provisions of this Section 4.3;
     provided, however, that such instrument may state that the obligation of
     the Company to make additional deposits as aforesaid shall be subject to
     the delivery to the Company by the Trustee of a notice asserting the
     deficiency accompanied by an opinion of an independent public accountant of
     nationally recognized standing, selected by the Trustee, showing the
     calculation thereof; or

           (B) an Opinion of Counsel, based on a change in law, to the effect
     that the Holders of such Outstanding Securities of such series, or portions
     of the principal amount thereof, will not recognize income, gain or loss
     for United States federal income tax purposes as a result of the
     satisfaction and discharge of the Company's indebtedness in respect thereof
     and will be subject to United States federal income tax on the same
     amounts, at the same times and in the same manner as if such satisfaction
     and discharge had not been effected.

     Any deposits with the Trustee referred to in Section 4.3(1) above shall be
irrevocable and shall be made under the terms of an escrow trust agreement in
form and substance reasonably satisfactory to the Trustee.  If any Outstanding
Securities of such series are to be redeemed prior to their Stated Maturity,
whether pursuant to any optional redemption provisions or in accordance with any
mandatory sinking fund requirement, the applicable escrow trust agreement shall
provide therefor and the Company shall make such arrangements as are
satisfactory to the Trustee for the giving of

                                       33
<PAGE>

notice of redemption by the Trustee in the name, and at the expense, of the
Company. If the Securities of such series are not to become due and payable at
their Stated Maturity or upon call for redemption within one (1) year of the
date of deposit, then the Company shall give, not later than the date of such
deposit, notice of such deposit to the Holders of Securities of such series.

     Upon satisfaction of the conditions set forth in this Section 4.3 with
respect to all the Outstanding Securities of any series, the terms and
conditions of such series, including the terms and conditions with respect
thereto set forth in this Indenture, shall no longer be binding upon, or
applicable to, the Company; provided, that the Company shall not be discharged
from any payment obligations in respect of Securities of such series which are
deemed not to be Outstanding under clause (iii) of the definition thereof if
such obligations continue to be valid obligations of the Company under
applicable law and provided further that the Company shall not be discharged
from its obligation to the Trustee under Section 6.7.


                                    ARTICLE V

                                    REMEDIES

     Section 5.1   Events of Default.

     "Event of Default," wherever used herein with respect to the Securities of
any series, means any one of the following events (whatever the reason for such
Event of Default and whether it shall be voluntary or involuntary or be effected
by operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

     (1)   the Company defaults in the payment of any interest upon any Security
of that series, including any Additional Interest in respect thereof, when it
becomes due and payable, and continuance of such default for a period of 30 days
(subject to the deferral of any due date in the case of an Extension Period); or

     (2)   the Company defaults in the payment of the principal of (or premium,
if any, on) any Security of that series at its Maturity; or

     (3)   the Company defaults in the performance, or breach, in any material
respect, of any of its covenants or warranties in this Indenture (other than a
covenant or warranty a default in the performance of which or the breach of
which is elsewhere in this Section specifically dealt with), and continuance of
such default or breach for a period of 90 days after there has been given, by
registered or certified mail, to the Company by the Trustee or to the Company
and the Trustee by the Holders of at least 25% in principal amount of the
Outstanding Securities of that series a written notice specifying such default
or breach and requiring it to be remedied; or

     (4)   the entry of a decree or order by a court having jurisdiction in the
premises adjudging the Company a bankrupt or insolvent, or approving as properly
filed a petition seeking reorganization, arrangement, adjustment or composition
of or in respect of the Company under any applicable United States federal or
state bankruptcy, insolvency, reorganization or other similar law, or appointing
a receiver, liquidator, assignee, trustee, sequestration (or other similar
official) of the Company or of

                                       34
<PAGE>

any substantial part of its property or ordering the winding up or liquidation
of its affairs, and the continuance of any such decree or order unstayed and in
effect for a period of 60 consecutive days; or

     (5)   the institution by the Company of proceedings to be adjudicated a
bankrupt or insolvent, or the consent by it to the institution of bankruptcy or
insolvency proceedings against it, or the filing by it of a petition or answer
or consent seeking reorganization or relief under any applicable United States
federal or state bankruptcy, insolvency, reorganization or other similar law, or
the consent by it to the filing of any such petition or to the appointment of a
receiver, liquidator, assignee, trustee, sequestration (or other similar
official) of the Company or of any substantial part of its property, or the
making by it of an assignment of the benefit of creditors, or the admission by
it in writing of its inability to pay its debts generally as they become due and
its willingness to be adjudicated a bankrupt, or the taking of corporate action
by the Company in furtherance of any such action; or

     (6)   any other Event of Default provided with respect to Securities of
that series.

     Section 5.2    Acceleration of Maturity; Rescission and Annulment.

     If an Event of Default (other than an Event of Default specified in Section
5.1(4) or 5.1(5)) with respect to Securities of any series at the time
Outstanding occurs and is continuing, then and in every such case the Trustee or
the Holders of not less than 25% in principal amount of the Outstanding
Securities of that series may declare the principal amount (or, if the
Securities of that series are Discount Securities, such portion of the principal
amount as may be specified in the terms of that series) of all the Securities of
that series to be due and payable immediately, by a notice in writing to the
Company (and to the Trustee if given by Holders), provided that, in the case of
the Securities of a series issued to a ONEOK Capital Trust, if, upon an Event of
Default, the Trustee or the Holders of not less than 25% in principal amount of
the Outstanding Securities of that series fail to declare the principal of all
the Securities of that series to be immediately due and payable, the holders of
at least 25% in aggregate liquidation amount of the corresponding series of
Preferred Securities then outstanding shall have such right by a notice in
writing to the Company and the Trustee; and upon any such declaration such
principal amount (or specified portion thereof) of and the accrued interest
(including any Additional Interest) on all the Securities of such series shall
become immediately due and payable.  Payment of principal and interest
(including any Additional Interest) on such Securities shall remain subordinated
to the extent provided in Article XIII notwithstanding that such amount shall
become immediately due and payable as herein provided.  If an Event of Default
specified in Section 5.1(4) or 5.1(5) with respect to Securities of any series
at the time Outstanding occurs, the principal amount of all the Securities of
that series (or, if the Securities of that series are Discount Securities, such
portion of the principal amount of such Securities as may be specified by the
terms of that series) shall automatically, and without any declaration or other
action on the part of the Trustee or any Holder, become immediately due and
payable.

     At any time after such a declaration of acceleration with respect to
Securities of any series has been made and before judgment or decree for payment
of the money due has been obtained by the Trustee as hereinafter in this Article
provided, the Holders of a majority in principal amount of the

                                       35
<PAGE>

Outstanding Securities of that series, by written notice to the Company and the
Trustee, may rescind and annul such declaration and its consequences if:

     (1)   the Company has paid or deposited with the Trustee a sum sufficient
to pay:

     (A)   all overdue installments of interest (including any Additional
Interest) on all Securities of that series,

     (B)   the principal of (and premium, if any, on) any Securities of that
series which have become due otherwise than by such declaration of acceleration
and interest thereon at the rate borne by the Securities, and

     (C)   all sums paid or advanced by the Trustee hereunder and the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and counsel; and

     (2)   all Events of Default with respect to Securities of that series,
other than the non-payment of the principal of Securities of that series which
has become due solely by such acceleration, have been cured or waived as
provided in Section 5.13.

     In the case of Securities of a series issued to a ONEOK Capital Trust, the
holders of  a majority in aggregate Liquidation Amount (as defined in the Trust
Agreement under which such ONEOK Capital Trust is formed) of the related series
of Preferred Securities issued by such ONEOK Capital Trust shall also have the
right to rescind and annul such declaration and its consequences by written
notice to the Company and the Trustee, subject to the satisfaction of the
conditions set forth in Clauses (1) and (2) above of this Section 5.2.

     No such rescission shall affect any subsequent default or impair any right
consequent thereon.

     Section 5.3  Collection of Indebtedness and Suits for Enforcement by
Trustee.

     The Company covenants that if:

     (1)   default is made in the payment of any installment of interest
(including any Additional Interest) on any Security when such interest becomes
due and payable and such default continues for a period of 30 days, or

     (2)   default is made in the payment of the principal of (and premium, if
any, on) any Security at the Maturity thereof the Company will, upon demand of
the Trustee, pay to the Trustee, for the benefit of the Holders of such
Securities, the whole amount then due and payable on such Securities for
principal, including any sinking fund payment or analogous obligations (and
premium, if any) and interest (including any Additional Interest); and, in
addition thereto, all amounts owing the Trustee under Section 6.7.

     If the Company fails to pay such amounts forthwith upon such demand, the
Trustee, in its own name and as trustee of an express trust, may institute a
judicial proceeding for the collection of the sums so due and unpaid, and may
prosecute such proceeding to judgment or final decree, and may enforce the same
against the Company or any other obligor upon the Securities and collect the

                                       36
<PAGE>

moneys adjudged or decreed to be payable in the manner provided by law out of
the property of the Company or any other obligor upon the Securities, wherever
situated.

     If an Event of Default with respect to Securities of any series occurs and
is continuing, the Trustee may in its discretion proceed to protect and enforce
its rights and the rights of the Holders of Securities of such series by such
appropriate judicial proceedings as the Trustee shall deem most effectual to
protect and enforce any such rights, whether for the specific enforcement of any
covenant or agreement in this Indenture or in aid of the exercise of any power
granted herein, or to enforce any other proper remedy.

     Section 5.4    Trustee May File Proofs of Claim.

     In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company of such other obligor or their
creditors, the Trustee (irrespective of whether the principal of the Securities
of any series shall then be due and payable as therein expressed or by
declaration or otherwise and irrespective of whether the Trustee shall have made
any demand on the Company for the payment of overdue principal (and premium, if
any) or interest (including any Additional Interest)) shall be entitled and
empowered, by intervention in such proceeding or otherwise,

     (i)   to file and prove a claim for the whole amount of principal (and
premium, if any) and interest (including any Additional Interest) owing and
unpaid in respect of the Securities and to file such other papers or documents
as may be necessary or advisable and to take any and all actions as are
authorized under the Trust Indenture Act in order to have the claims of the
Holders and any predecessor to the Trustee under Section 6.7 allowed in any such
judicial proceedings; and

     (ii)  in particular, the Trustee shall be authorized to collect and receive
any moneys or other property payable or deliverable on any such claims and to
distribute the same in accordance with Section 5.6; and

     (iii) any custodian, receiver, assignee, trustee, liquidator, sequesterator
(or other similar official) in any such judicial proceeding is hereby authorized
by each Holder to make such payments to the Trustee for distribution in
accordance with Section 5.6, and in the event that the Trustee shall consent to
the making of such payments directly to the Holders, to pay to the Trustee any
amount due to it and any predecessor Trustee under Section 6.7.

     Nothing herein contained shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment or composition affecting the Securities
or the rights of any Holder thereof, or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding; provided, however,
that the Trustee may, on behalf of the Holders, vote for the election of a
trustee in bankruptcy or similar official and be a member of a creditors' or
other similar committee.

     Section 5.5    Trustee May Enforce Claim Without Possession of Securities.

                                       37
<PAGE>

     All rights of action and claims under this Indenture or the Securities may
be prosecuted and enforced by the Trustee without the possession of any of the
Securities or the production thereof in any proceeding relating thereto, and any
such proceeding instituted by the Trustee shall be brought in its own name as
trustee of an express trust, and any recovery of judgment shall, after provision
for the payment of all the amounts owing the Trustee and any predecessor Trustee
under Section 6.7, its agents and counsel, be for the ratable benefit of the
Holders of the Securities in respect of which such judgment has been recovered.

     Section 5.6    Application of Money Collected.

     Any money or property collected or to be applied by the Trustee with
respect to a series of Securities pursuant to this Article shall be applied in
the following order, at the date or dates fixed by the Trustee and, in case of
the distribution of such money or property on account of principal (or premium,
if any) or interest (including any Additional Interest), upon presentation of
the Securities and the notation thereon of the payment if only partially paid
and upon surrender thereof if fully paid:

     FIRST:    To the payment of all amounts due the Trustee and any predecessor
Trustee under Section 6.7;

     SECOND:   Subject to Article XIII, to the payment of the amounts then due
and unpaid upon such series of Securities for principal (and premium, if any)
and interest (including any Additional Interest), in respect of which or for the
benefit of which such money has been collected, ratably, without preference or
priority of any kind, according to the amounts due and payable on such series of
Securities for principal (and premium, if any) and interest (including any
Additional Interest), respectively; and

     THIRD:    The balance, if any, to the Person or Persons entitled thereto.

     Section 5.7    Limitation on Suits.

     No Holder of any Securities of any series shall have any right to institute
any proceeding, judicial or otherwise, with respect to this Indenture or for the
appointment of a receiver, assignee, trustee, liquidator, sequesterator (or
other similar official) or for any other remedy hereunder, unless:

     (1)   such Holder has previously given written notice to the Trustee of a
continuing Event of Default with respect to the Securities of that series;

     (2)   the Holders of not less than 25% in principal amount of the
Outstanding Securities of that series shall have made written request to the
Trustee to institute proceedings in respect of such Event of Default in its own
name as Trustee hereunder;

     (3)   such Holder or Holders have offered to the Trustee reasonable
indemnity against the costs, expenses and liabilities to be incurred in
compliance with such request;

     (4)   the Trustee for 60 days after its receipt of such notice, request and
offer of indemnity has failed to institute any such proceeding; and

                                       38
<PAGE>

     (5)   no direction inconsistent with such written request has been given to
the Trustee during such 60-day period by the Holders of a majority in principal
amount of the Outstanding Securities of that series; it being understood and
intended that no one or more of such Holders shall have any right in any manner
whatever by virtue of, or by availing itself of, any provision of this Indenture
to affect, disturb or prejudice the rights of any other Holders of Securities,
or to obtain or to seek to obtain priority or preference over any other of such
Holders or to enforce any right under this Indenture, except in the manner
herein provided and for the equal and ratable benefit of all such Holders.

     Section 5.8    Unconditional Right of Holders to Receive Principal, Premium
and Interest; Direct Action by Holders of Preferred Securities.

     Notwithstanding any other provision in this Indenture, the Holder of any
Security shall have the right which is absolute and unconditional to receive
payment of the principal of (and premium, if any) and (subject to Section 3.7)
interest (including any Additional Interest) on such Security on the respective
Stated Maturities expressed in such Security (or, in the case of redemption, on
the Redemption Date) and to institute suit for the enforcement of any such
payment, and such right shall not be impaired without the consent of such
Holder.  In the case of Securities of a series issued to a ONEOK Capital Trust,
any holder of the corresponding series of Preferred Securities issued by such
ONEOK Capital Trust shall have the right, upon the occurrence of an Event of
Default described in Section 5.1(1) or 5.1(2), to institute a suit directly
against the Company for enforcement of payment to such holder of principal of
(premium, if any) and (subject to Section 3.7) interest (including any
Additional Interest) on the Securities having a principal amount equal to the
aggregate Liquidation Amount (as defined in the Trust Agreement under which such
ONEOK Capital Trust is formed) of such Preferred Securities of the corresponding
series held by such holder.

     Section 5.9    Restoration of Rights and Remedies.

     If the Trustee, any Holder or any holder of Preferred Securities has
instituted any proceeding to enforce any right or remedy under this Indenture
and such proceeding has been discontinued or abandoned for any reason, or has
been determined adversely to the Trustee, such Holder or such holder of
Preferred Securities, then and in every such case the Company, the Trustee, the
Holders and such holder of Preferred Securities shall, subject to any
determination in such proceeding, be restored severally and respectively to
their former positions hereunder, and thereafter all rights and remedies of the
Trustee, the Holders and the holders of Preferred Securities shall continue as
though no such proceeding had been instituted.

     Section 5.10   Rights and Remedies Cumulative.

     Except as otherwise provided in the last paragraph of Section 3.6, no right
or remedy herein conferred upon or reserved to the Trustee or to the Holders is
intended to be exclusive of any other right or remedy, and every right and
remedy shall, to the extent permitted by law, be cumulative and in addition to
every other right and remedy given hereunder or now or hereafter existing at law
or in equity or otherwise.  The assertion or employment of any right or remedy
hereunder, or otherwise, shall not prevent the concurrent assertion or
employment of any other appropriate right or remedy.

     Section 5.11   Delay or Omission Not Waiver.

                                       39
<PAGE>

     No delay or omission of the Trustee, any Holder of any Security or any
holder of any Preferred Security to exercise any right or remedy accruing upon
any Event of Default shall impair any such right or remedy or constitute a
waiver of any such Event of Default or an acquiescence therein.

     Every right and remedy given by this Article or by law to the Trustee or to
the Holders and the right and remedy given to the holders of Preferred
Securities by Section 5.8 may be exercised from time to time, and as often as
may be deemed expedient, by the Trustee, the Holders or the holders of Preferred
Securities, as the case may be.

     Section 5.12   Control by Holders.

     The Holders of a majority in principal amount of the Outstanding Securities
of any series shall have the right to direct the time, method and place of
conducting any proceeding for any remedy available to the Trustee or exercising
any trust or power conferred on the Trustee, with respect to the Securities of
such series, provided that:

     (1)   such direction shall not be in conflict with any rule of law or with
this Indenture,

     (2)   the Trustee may take any other action deemed proper by the Trustee
which is not inconsistent with such direction, and

     (3)   subject to the provisions of Section 6.1, the Trustee shall have the
right to decline to follow such direction if a Responsible Officer or Officers
of the Trustee shall, in good faith, determine that the proceeding so directed
would be unjustly prejudicial to the Holders not joining in any such direction
or would involve the Trustee in personal liability.

     Section 5.13   Waiver of Past Defaults.

     The Holders of  a majority in principal amount of the Outstanding
Securities of any series and, in the case of any Securities of a series issued
to a ONEOK Capital Trust, the holders of  a majority in aggregate liquidation
amount Preferred Securities issued by such ONEOK Capital Trust may waive any
past default hereunder and its consequences with respect to such series except a
default:

     (1)   in the payment of the principal of (or premium, if any) or interest
(including any Additional Interest) on any Security of such series, or

     (2)   in respect of a covenant or provision hereof which under Article IX
cannot be modified or amended without the consent of the Holder of each
Outstanding Security of such series affected.

     Any such waiver shall be deemed to be on behalf of the Holders of all the
Securities of such series or, in the case of a waiver by holders of Preferred
Securities issued by such ONEOK Capital Trust, by all holders of Preferred
Securities issued by such ONEOK Capital Trust.

                                       40
<PAGE>

     Upon any such waiver, such default shall cease to exist, and any Event of
Default arising therefrom shall be deemed to have been cured, for every purpose
of this Indenture; but no such waiver shall extend to any subsequent or other
default or impair any right consequent thereon.

     Section 5.14   Undertaking for Costs.

     All parties to this Indenture agree, and each Holder of any Security by his
acceptance thereof shall be deemed to have agreed, that any court may in its
discretion require, in any suit for the enforcement of any right or remedy under
this Indenture, or in any suit against the Trustee for any action taken or
omitted by it as Trustee, the filing by any party litigant in such suit of an
undertaking to pay the costs of such suit, and that such court may in its
discretion assess reasonable costs, including reasonable attorneys' fees,
against any party litigant in such suit, having due regard to the merits and
good faith of the claims or defenses made by such party litigant; but the
provisions of this Section shall not apply to any suit instituted by the
Trustee, to any suit instituted by any Holder, or group of Holders, holding in
the aggregate more than 10% in principal amount of the Outstanding Securities of
any series, or to any suit instituted by any Holder for the enforcement of the
payment of the principal of (or premium, if any) or interest (including any
Additional Interest) on any Security on or after the respective Stated
Maturities expressed in such Security.

     Section 5.15   Waiver of Usury, Stay or Extension Laws.

     The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, or plead, or in any manner whatsoever claim or
take the benefit or advantage of, any usury, stay or extension law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives any benefit or advantage of any such
law, and covenants that it will not hinder, delay or impede the execution of any
power herein granted to the Trustee, but will suffer and permit the execution of
every such power as though no such law had been enacted.


                                  ARTICLE VI

                                  THE TRUSTEE

     Section 6.1    Certain Duties and Responsibilities.

     (a)  Except during the continuance of an Event of Default,

          (1)  the Trustee undertakes to perform such duties and only such
duties as are specifically set forth in this Indenture, and no implied covenants
or obligations shall be read into this Indenture against the Trustee; and

          (2)  in the absence of bad faith on its part, the Trustee may
conclusively rely, as to the truth of the statements and the correctness of the
opinions expressed therein, upon certificates or opinions furnished to the
Trustee and conforming to the requirements of this Indenture; but in the case of
any such certificates or opinions which by any provisions hereof are
specifically required to

                                       41
<PAGE>

be furnished to the Trustee, the Trustee shall be under a duty to examine the
same to determine whether or not they conform to the requirements of this
Indenture.

     (b)  In case an Event of Default has occurred and is continuing, the
Trustee shall exercise such of the rights and powers vested in it by this
Indenture, and use the same degree of care and skill in their exercise, as a
prudent person would exercise or use under the circumstances in the conduct of
his own affairs.

     (c)  No provision of this Indenture shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act, or its own willful misconduct except that:

          (1)  this Subsection shall not be construed to limit the effect of
Subsection (a) of this Section;

          (2)  the Trustee shall not be liable for any error of judgment made in
good faith by a Responsible Officer; unless it shall be proved that the Trustee
was negligent in ascertaining the pertinent facts; and

          (3)  the Trustee shall not be liable with respect to any action taken
or omitted to be taken by it in good faith in accordance with the direction of
Holders pursuant to Section 5.12 relating to the time, method and place of
conducting any proceeding for any remedy available to the Trustee, or exercising
any trust or power conferred upon the Trustee, under this Indenture with respect
to the Securities of such series.

     (d)  No provision of this Indenture shall require the Trustee to expend or
risk its own funds or otherwise incur any financial liability in the performance
of any of its duties hereunder, or in the exercise of any of its rights or
powers, if there shall be reasonable grounds for believing that repayment of
such funds or adequate indemnity against such risk or liability is not
reasonably assured to it.

     (e)  Whether or not therein expressly so provided, every provision of this
Indenture relating to the conduct or affecting the liability of or affording
protection to the Trustee shall be subject to the provisions of this Section.

     Section 6.2    Notice of Defaults.

     Within 90 days after actual knowledge by a Responsible Officer of the
Trustee of the occurrence of any default hereunder with respect to the
Securities of any series, the Trustee shall transmit by mail to all Holders of
Securities of such series, as their names and addresses appear in the Securities
Register, notice of such default, unless such default shall have been cured or
waived; provided, however, that, except in the case of a default in the payment
of the principal of (or premium, if any) or interest (including any Additional
Interest) on any Security of such series, the Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee or a trust committee of directors and/or Responsible Officers of the
Trustee in good faith determines that the withholding of such notice is in the
interests of the Holders of Securities of such series; and provided, further,
that, in the case of any default of the character specified in Section 5.1(3),
no such notice to Holders of Securities of such series shall be given until

                                       42
<PAGE>

at least 30 days after the occurrence thereof. For the purpose of this Section,
the term "default" means any event which is, or after notice or lapse of time or
both would become, an Event of Default with respect to Securities of such
series.

     Section 6.3    Certain Rights of Trustee.

     Subject to the provisions of Section 6.1:

     (a)  the Trustee may rely and shall be protected in acting or refraining
from acting upon any resolution, certificate, statement, instrument, opinion,
report, notice, request, direction, consent, order, bond, debenture, Security or
other paper or document believed by it to be genuine and to have been signed or
presented by the proper party or parties;

     (b)  any request or direction of the Company mentioned herein shall be
sufficiently evidenced by a Company Request or Company Order and any resolution
of the Board of Directors may be sufficiently evidenced by a Board Resolution;

     (c)  whenever in the administration of this Indenture the Trustee shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, the Trustee (unless other evidence
be herein specifically prescribed) may, in the absence of bad faith on its part,
rely upon an Officers' Certificate;

     (d)  the Trustee may consult with counsel and the advice of such counsel or
any Opinion of Counsel shall be full and complete authorization and protection
in respect of any action taken, suffered or omitted by it hereunder in good
faith and in reliance thereon;

     (e)  the Trustee shall be under no obligation to exercise any of the rights
or powers vested in it by this Indenture at the request or direction of any of
the Holders pursuant to this Indenture, unless such Holders shall have offered
to the Trustee reasonable security or indemnity against the costs, expenses and
liabilities which might be incurred by it in compliance with such request or
direction;

     (f)  the Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, indenture,
Security or other paper or document, but the Trustee in its discretion may make
such inquiry or investigation into such facts or matters as it may see fit, and,
if the Trustee shall determine to make such inquiry or investigation, it shall
be entitled to examine the books, records and premises of the Company,
personally or by agent or attorney; and

     (g)  the Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through agents or
attorneys and the Trustee shall not be responsible for any misconduct or
negligence on the part of any agent or attorney appointed with due care by it
hereunder.

     Section 6.4    Not Responsible for Recitals or Issuance of Securities.

                                       43
<PAGE>

     The recitals contained herein and in the Securities, except the Trustee's
certificates of authentication, shall be taken as the statements of the Company,
and neither the Trustee nor any Authenticating Agent assumes any responsibility
for their correctness.  The Trustee makes no representations as to the validity
or sufficiency of this Indenture or of the Securities.  Neither the Trustee nor
any Authenticating Agent shall be accountable for the use or application by the
Company of the Securities or the proceeds thereof.

     Section 6.     May Hold Securities.

     The Trustee, any Authenticating Agent, any Paying Agent, any Securities
Registrar or any other agent of the Company, in its individual or any other
capacity, may become the owner or pledgee of Securities and, subject to Sections
6.8 and 6.13, may otherwise deal with the Company with the same rights it would
have if it were not Trustee, Authenticating Agent, Paying Agent, Securities
Registrar or such other agent.

     Section 6.6    Money Held in Trust.

     Money held by the Trustee in trust hereunder need not be segregated from
other funds except to the extent required by law.  The Trustee shall be under no
liability for interest on any money received by it hereunder except as otherwise
agreed with the Company.

     Section 6.7    Compensation and Reimbursement.

     The Company agrees:

     (1)  to pay to the Trustee from time to time reasonable compensation for
all services rendered by it hereunder in such amounts as the Company, and the
Trustee shall agree from time to time (which compensation shall not be limited
by any provision of law in regard to the compensation of a trustee of an express
trust);

     (2)  to reimburse the Trustee upon its request for all reasonable expenses,
disbursements and advances incurred or made by the Trustee in accordance with
any provision of this Indenture (including the reasonable compensation and the
expenses and disbursements of its agents and counsel), except any such expense,
disbursement or advance as may be attributable to its negligence or bad faith;
and

     (3)  to indemnify the Trustee for, and to hold it harmless against, any
loss, liability or expense (including the reasonable compensation and the
expenses and disbursements of its agents and counsel) incurred without
negligence or bad faith, arising out of or in connection with the acceptance or
administration of this trust or the performance of its duties hereunder,
including the costs and expenses of defending itself against any claim or
liability in connection with the exercise or performance of any of its powers or
duties hereunder.  This indemnification shall survive the termination of this
Indenture and the resignation or removal of the Trustee.

     To secure the Company's payment obligations in this Section, the Company,
and the Holders agree that the Trustee shall have a lien prior to the Securities
on all money or property held or collected by the Trustee.  Such lien shall
survive the satisfaction and discharge of this Indenture.

                                       44
<PAGE>

     When the Trustee incurs expenses or renders services after an Event of
Default specified in Section 5.1(4) or (5) occurs, the expenses and the
compensation for the services are intended to constitute expenses of
administration under the Bankruptcy Reform Act of 1978 or any successor statute.

     Section 6.8    Disqualification; Conflicting Interests.

     The Trustee for the Securities of any series issued hereunder shall be
subject to the provisions of Section 310(b) of the Trust Indenture Act.  Nothing
herein shall prevent the Trustee from filing with the Commission the application
referred to in the second to last paragraph of said Section 310(b).  Each Trust
Agreement and ONEOK Capital Guarantee are hereby excluded from the provision of
Section 310(b)(1) of the Trust Indenture Act.

     Section 6.9    Corporate Trustee Required; Eligibility.

     There shall at all times be a Trustee hereunder which shall be

     (a)  a corporation organized and doing business under the laws of the
United States of America or of any State or Territory or the District of
Columbia, authorized under such laws to exercise corporate trust powers and
subject to supervision or examination by United States federal, state,
territorial or District of Columbia authority, or

     (b)  a corporation or other Person organized and doing business under the
laws of a foreign government that is permitted to act as Trustee pursuant to a
rule, regulation or order of the Commission, authorized under such laws to
exercise corporate trust powers, and subject to supervision or examination by
authority of such foreign government or a political subdivision thereof
substantially equivalent to supervision or examination applicable to United
States institutional trustees, in either case having a combined capital and
surplus of at least $50,000,000, subject to supervision or examination by United
States federal or state authority. If such corporation publishes reports of
condition at least annually, pursuant to law or to the requirements of the
aforesaid supervising or examining authority, then, for the purposes of this
Section, the combined capital and surplus of such corporation shall be deemed to
be its combined capital and surplus as set forth in its most recent report of
condition so published. If at any time the Trustee shall cease to be eligible in
accordance with the provisions of this Section, it shall resign immediately in
the manner and with the effect hereinafter specified in this Article. Neither
the Company, nor any Person directly or indirectly controlling, controlled by or
under common control with the Company shall serve as Trustee for the Securities
of any series issued hereunder.

     Section 6.10   Resignation and Removal; Appointment of Successor.

     (a)  No resignation or removal of the Trustee and no appointment of a
successor Trustee pursuant to this Article shall become effective until the
acceptance of appointment by the successor Trustee under Section 6.11.

     (b)  The Trustee may resign at any time with respect to the Securities of
one or more series by giving written notice thereof to the Company.  If an
instrument of acceptance by a successor Trustee shall not have been delivered to
the Trustee within 30 days after the giving of such notice of

                                       45
<PAGE>

resignation, the resigning Trustee may petition any court of competent
jurisdiction for the appointment of a successor Trustee with respect to the
Securities of such series.

     (c)  The Trustee may be removed at any time with respect to the Securities
of any series by Act of the Holders of a majority in principal amount of the
Outstanding Securities of such series, delivered to the Trustee and to the
Company.

     (d)  If at any time:

          (1)  the Trustee shall fail to comply with Section 6.8 after written
request therefor by the Company, or by any Holder who has been a bona fide
Holder of a Security for at least six months, or

          (2)  the Trustee shall cease to be eligible under Section 6.9 and
shall fail to resign after written request therefor by the Company, or by any
such Holder, or

          (3)  the Trustee shall become incapable of acting or shall be adjudged
a bankrupt or insolvent or a receiver of the Trustee or of its property shall be
appointed or any public officer shall take charge or control of the Trustee or
of its property or affairs for the purpose of rehabilitation, conservation or
liquidation, then, in any such case, (i) the Company acting pursuant to the
authority of a Board Resolution, may remove the Trustee with respect to all
Securities, or (ii) subject to Section 5.14, any Holder who has been a bona fide
Holder of a Security for at least six months may, on behalf of himself and all
others similarly situated, petition any court of competent jurisdiction for the
removal of the Trustee with respect to all Securities and the appointment of a
successor Trustee or Trustees.

     (e)  If the Trustee shall resign, be removed or become incapable of acting,
or if a vacancy shall occur in the office of Trustee for any cause with respect
to the Securities of one or more series, the Company, by a Board Resolution,
shall promptly appoint a successor Trustee with respect to the Securities of
that or those series.  If, within one year after such resignation, removal or
incapability, or the occurrence of such vacancy, a successor Trustee with
respect to the Securities of any series shall be appointed by Act of the Holders
of a majority in principal amount of the Outstanding Securities of such series
delivered to the Company and the retiring Trustee, the successor Trustee so
appointed shall, forthwith upon its acceptance of such appointment, become the
successor Trustee with respect to the Securities of such series and supersede
the successor Trustee appointed by the Company.  If no successor Trustee with
respect to the Securities of any series shall have been so appointed by the
Company or the Holders and accepted appointment in the manner hereinafter
provided, any Holder who has been a bona fide Holder of a Security for at least
six months may, subject to Section 5.14, on behalf of himself and all others
similarly situated, petition any court of competent jurisdiction for the
appointment of a successor Trustee with respect to the Securities of such
series.

     (f)  The Company shall give notice of each resignation and each removal of
the Trustee with respect to the Securities of any series and each appointment of
a successor Trustee with respect to the Securities of any series by mailing
written notice of such event by first-class mail, postage prepaid, to the
Holders of Securities of such series as their names and addresses appear in the

                                       46
<PAGE>

Securities Register. Each notice shall include the name of the successor Trustee
with respect to the Securities of such series and the address of its Corporate
Trust Office.

     Section 6.1    Acceptance of Appointment by Successor.

     (a)  In case of the appointment hereunder of a successor Trustee with
respect to all Securities, every such successor Trustee so appointed shall
execute, acknowledge and deliver to the Company and to the retiring Trustee an
instrument accepting such appointment, and thereupon the resignation or removal
of the retiring Trustee shall become effective and such successor Trustee,
without any further act, deed or conveyance, shall become vested with all the
rights, powers, trusts and duties of the retiring Trustee; but, on the request
of the Company or the successor Trustee, such retiring Trustee shall, upon
payment of its charges, execute and deliver an instrument transferring to such
successor Trustee all the rights, powers and trusts of the retiring Trustee and
shall duly assign, transfer and deliver to such successor Trustee all property
and money held by such retiring Trustee hereunder.

     (b)  In case of the appointment hereunder of a successor Trustee with
respect to the Securities of one or more (but not all) series, the Company, the
retiring Trustee and each successor Trustee with respect to the Securities of
any series shall execute and deliver an indenture supplemental hereto wherein
each successor Trustee shall accept such appointment and which (1) shall contain
such provisions as shall be necessary or desirable to transfer and confirm to,
and to vest in, each successor Trustee all the rights, powers, trusts and duties
of the retiring Trustee with respect to the Securities of that or those series
to which the appointment of such successor Trustee relates, (2) if the retiring
Trustee is not retiring with respect to all Securities, shall contain such
provisions as shall be deemed necessary or desirable to confirm that all the
rights, powers, trusts and duties of the retiring Trustee with respect to the
Securities of that or those series as to which the retiring Trustee is not
retiring shall continue to be vested in the retiring Trustee, and (3) shall add
to or change any of the provisions of this Indenture as shall be necessary to
provide for or facilitate the administration of the trusts hereunder by more
than one Trustee, it being understood that nothing herein or in such
supplemental indenture shall constitute such Trustees co-trustees of the same
trust and that each such Trustee shall be trustee of a trust or trusts hereunder
separate and apart from any trust or trusts hereunder administered by any other
such Trustee; and upon the execution and delivery of such supplemental indenture
the resignation or removal of the retiring Trustee shall become effective to the
extent provided therein and each such successor Trustee, without any further
act, deed or conveyance, shall become vested with all the rights, powers,
trusts, and duties of the retiring Trustee with respect to the Securities of any
series to which the appointment of such successor Trustee relates; but, on
request of the Company or any successor Trustee, such retiring Trustee shall
duly assign, transfer and deliver to such successor Trustee all property and
money held by such retiring Trustee hereunder with respect to the Securities of
that or those series to which the appointment of such successor Trustee relates.

     (c)  Upon request of any such successor Trustee, the Company shall execute
any and all instruments for more fully and certainly vesting in and confirming
to such successor Trustee all rights, powers and trusts referred to in paragraph
(a) or (b) of this Section, as the case may be.

     (d)  No successor Trustee shall accept its appointment unless at the time
of such acceptance such successor Trustee shall be qualified and eligible under
this Article.

                                       47
<PAGE>

     Section 6.12   Merger, Conversion, Consolidation or Succession to Business.

     Any corporation into which the Trustee may be merged or converted or with
which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of the Trustee, shall be the successor of the Trustee hereunder,
provided such corporation shall be otherwise qualified and eligible under this
Article, without the execution or filing of any paper or any further act on the
part of any of the parties hereto.  In case any Securities shall have been
authenticated, but not delivered, by the Trustee then in office, any successor
by merger, conversion or consolidation to such authenticating Trustee may adopt
such authentication and deliver the Securities so authenticated, and in case any
Securities shall not have been authenticated, any successor to the Trustee may
authenticate such Securities either in the name of any predecessor Trustee or in
the name of such successor Trustee, and in all cases the certificate of
authentication shall have the full force which it is provided anywhere in the
Securities or in this Indenture that the certificate of the Trustee shall have.

     Section 6.13   Preferential Collection of Claims Against Company.

     If and when the Trustee shall be or become a creditor of the Company or any
other obligor upon the Securities, the Trustee shall be subject to the
provisions of the Trust Indenture Act regarding the collection of claims against
the Company or any such other obligor.

     Section 6.14   Appointment of Authenticating Agent.

     The Trustee may appoint an Authenticating Agent or Agents with respect to
one or more series of Securities which shall be authorized to act on behalf of
the Trustee to authenticate Securities of such series issued upon original issue
and upon exchange, registration of transfer or partial redemption thereof or
pursuant to Section 3.6, and Securities so authenticated shall be entitled to
the benefits of this Indenture and shall be valid and obligatory for all
purposes as if authenticated by the Trustee hereunder.  Wherever reference is
made in this Indenture to the authentication and delivery of Securities by the
Trustee or the Trustee's certificate of authentication, such reference shall be
deemed to include authentication and delivery on behalf of the Trustee by an
Authenticating Agent. Each Authenticating Agent shall be acceptable to the
Company shall at all times be a corporation organized and doing business under
the laws of the United States of America, or of any State or Territory or the
District of Columbia, authorized under such laws to act as Authenticating Agent,
having a combined capital and surplus of not less than $50,000,000, except for
Affiliates of the Trustee, and subject to supervision or examination by United
States federal or state authority.  If such Authenticating Agent publishes
reports of condition at least annually, pursuant to law or to the requirements
of said supervising or examining authority, then for the purposes of this
Section the combined capital and surplus of such Authenticating Agent shall be
deemed to be its combined capital and surplus as set forth in its most recent
report of condition so published.  If at any time an Authenticating Agent shall
cease to be eligible in accordance with the provisions of this Section, such
Authenticating Agent shall resign immediately in the manner and with the effect
specified in this Section.

     Any corporation into which an Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or

                                       48
<PAGE>

consolidation to which such Authenticating Agent shall be a party, or any
corporation succeeding to all or substantially all of the corporate trust
business of an Authenticating Agent shall be the successor Authenticating Agent
hereunder, provided such corporation shall be otherwise eligible under this
Section, without the execution or filing of any paper or any further act on the
part of the Trustee or the Authenticating Agent.

     An Authenticating Agent may resign at any time by giving written notice
thereof to the Trustee and the Company.  The Trustee may at any time terminate
the agency of an Authenticating Agent by giving written notice thereof to such
Authenticating Agent and the Company.  Upon receiving such a notice of
resignation or upon such a termination, or in case at any time such
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section, the Trustee may appoint a successor Authenticating
Agent which shall be acceptable to the Company and shall give notice of such
appointment in the manner provided in Section 1.6 to all Holders of Securities
of the series with respect to which such Authenticating Agent will serve.  Any
successor Authenticating Agent upon acceptance of its appointment hereunder
shall become vested with all the rights, powers and duties of its predecessor
hereunder, with like effect as if originally named as an Authenticating Agent.
No successor Authenticating Agent shall be appointed unless eligible under the
provision of this Section.

     The Trustee agrees to pay to each Authenticating Agent from time to time
reasonable compensation for its services under this Section, and the Trustee
shall be entitled to be reimbursed for such payments, subject to the provisions
of Section 6.7.

     If an appointment with respect to one or more series is made pursuant to
this Section, the Securities of such series may have endorsed thereon, in
addition to the Trustee's certificate of authentication, an alternative
certificate of authentication in the following form:

     This is one of the Securities referred to in the within-mentioned
Indenture.



Dated:_______________________________


As Trustee


By:__________________________________
     As Authenticating Agent


By:__________________________________
     Authorized Officer


                                   ARTICLE VII

                                       49
<PAGE>

               HOLDER'S LISTS AND REPORTS BY TRUSTEE AND COMPANY

     Section 7.1    Company to Furnish Trustee Names and Addresses of Holders.

     The Company will furnish or cause to be furnished to the Trustee:

     (a)  semi-annually, not more than 15 days after January 15 and July 15 in
each year, a list, in such form as the Trustee may reasonably require, of the
names and addresses of the Holders as of such January 1 and July 1, and

     (b)  at such other times as the Trustee may request in writing, within 30
days after the receipt by the Company of any such request, a list of similar
form and content as of a date not more than 15 days prior to the time such list
is furnished, excluding from any such list names and addresses received by the
Trustee in its capacity as Securities Registrar.

     Section 7.2    Preservation of Information, Communications to Holders.

     (a)  The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 7.1 and the names and
addresses of Holders received by the Trustee in its capacity as Securities
Registrar.  The Trustee may destroy any list furnished to it as provided in
Section 7.1 upon receipt of a new list so furnished.

     (b)  The rights of Holders to communicate with other Holders with respect
to their rights under this Indenture or under the Securities, and the
corresponding rights and privileges of the Trustee, shall be as provided in the
Trust Indenture Act.

     (c)  Every Holder of Securities, by receiving and holding the same, agrees
with the Company and the Trustee that none of the Company the Trustee or any
agent of either of them shall be held accountable by reason of the disclosure of
information as to the names and addresses of the Holders made pursuant to the
Trust Indenture Act.

     Section 7.2    Reports by Trustee.

     (a)  The Trustee shall transmit to Holders such reports concerning the
Trustee and its actions under this Indenture as may be required pursuant to the
Trust Indenture Act, at the times and in the manner provided pursuant thereto.

     (b)  Reports so required to be transmitted at stated intervals of not more
than 12 months shall be transmitted no later than 60 days following May 15 in
each calendar year, commencing after the first issuance of Securities under this
Indenture.

     (c)  A copy of each such report shall, at the time of such transmission to
Holders, be filed by the Trustee with each stock exchange upon which any
Securities are listed and also with the Commission.  The Company will notify the
Trustee when any Securities are listed on any stock exchange.

                                       50
<PAGE>

     Section 7.4    Reports by the Company.

     The Company shall file with the Trustee and with the Commission, and
transmit to Holders, such information, documents and other reports, and such
summaries thereof, as may be required pursuant to the Trust Indenture Act at the
times and in the manner provided in the Trust Indenture Act; provided that any
such information, documents or reports required to be filed with the Commission
pursuant to Section 13 or Section 15(d) of the Exchange Act shall be filed with
the Trustee within 15 days after the same is required to be filed with the
Commission.  Notwithstanding that the Company may not be required to remain
subject to the reporting requirements of Section 13 or 15(d) of the Exchange
Act, the Company shall continue to file with the Commission and provide the
Trustee with the annual reports and the information, documents and other reports
which are specified in Sections 13 and 15(d) of the Exchange Act.  The Company
also shall comply with the other provisions of Section 314(a) of the Trust
Indenture Act.


                                 ARTICLE VIII

             CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

     Section 8.1    Company May Consolidate, Etc., Only on Certain Terms.

     The Company shall not consolidate with or merge into any other Person or
convey, transfer or lease its properties and assets substantially as an entirety
to any Person, and no Person shall consolidate with or merge into the Company or
convey, transfer or lease its properties and assets substantially as an entirety
to the Company, unless:

     (1)  in case the Company shall consolidate with or merge into another
Person or convey, transfer or lease its properties and assets substantially as
an entirety to any Person, the corporation formed by such consolidation or into
which the Company is merged or the Person which acquires by conveyance or
transfer, or which leases, the properties and assets of the Company
substantially as an entirety shall be a corporation, partnership or trust and
shall expressly assume, by an indenture supplemental hereto, executed and
delivered to the Trustee, in form satisfactory to the Trustee, the due and
punctual payment of the principal of (and premium, if any) and interest
(including any Additional Interest) on all the Securities and the performance of
every covenant of this Indenture on the part of the Company to be performed or
observed;

     (2)  immediately after giving effect to such transaction, no Event of
Default, and no event which, after notice or lapse of time, or both, would
become an Event of Default, shall have happened and be continuing;

     (3)  in the case of the Securities of a series issued to a ONEOK Capital
Trust, such consolidation, merger, conveyance, transfer or lease is permitted
under the related Trust Agreement and ONEOK Capital Guarantee and does not give
rise to any breach or violation of the related Trust Agreement or ONEOK Capital
Guarantee; and

     (4)  the Company has delivered to the Trustee an Officers' Certificate and
an Opinion of Counsel, each stating that such consolidation, merger, conveyance,
transfer or lease and any such

                                       51
<PAGE>

supplemental indenture comply with this Article and that all conditions
precedent herein provided relating to such transaction have been complied with;
and the Trustee, subject to Section 6.1, may rely upon such Officers'
Certificate and Opinion of Counsel as conclusive evidence that such transaction
complies with this Section 8.1.

     Section 8.2    Successor Corporation Substituted.

     Upon any consolidation or merger by the Company with or into any other
Person, or any conveyance, transfer or lease by the Company of its properties
and assets substantially as an entirety to any Person in accordance with Section
8.1, the successor corporation formed by such consolidation or into which the
Company is merged or to which such conveyance, transfer or lease is made shall
succeed to, and be substituted for, and may exercise every right and power of,
the Company, under this Indenture with the same effect as if such successor
Person had been named as the Company herein; and in the event of any such
conveyance, transfer or lease the Company, shall be discharged from all
obligations and covenants under the Indenture and the Securities and may be
dissolved and liquidated.

     Such successor Person may cause to be signed, and may issue either in its
own name or in the name of the Company any or all of the Securities issuable
hereunder which theretofore shall not have been signed by the Company and
delivered to the Trustee; and, upon the order of such successor Person instead
of the Company and subject to all the terms, conditions and limitations in this
Indenture prescribed, the Trustee shall authenticate and shall deliver any
Securities which previously shall have been signed and delivered by the officers
of the Company to the Trustee for authentication pursuant to such provisions and
any Securities which such successor Person thereafter shall cause to be signed
and delivered to the Trustee on its behalf for the purpose pursuant to such
provisions.  All the Securities so issued shall in all respects have the same
legal rank and benefit under this Indenture as the Securities theretofore or
thereafter issued in accordance with the terms of this Indenture as though all
of such Securities had been issued at the date of the execution hereof.

     In case of any such consolidation, merger, sale, conveyance or lease, such
changes in phraseology and form may be made in the Securities thereafter to be
issued as may be appropriate.


                                  ARTICLE IX

                            SUPPLEMENTAL INDENTURES

     Section 9.1    Supplemental Indentures without Consent of Holders.

     Without the consent of any Holders, the Company, when authorized by a Board
Resolution, and the Trustee, at any time and from time to time, may enter into
one or more indentures supplemental hereto, in form satisfactory to the Trustee,
for any of the following purposes:

     (1)  to evidence the succession of another Person to the Company, and the
assumption by any such successor of the covenants of the Company herein and in
the Securities contained; or

                                       52
<PAGE>

     (2)  to convey, transfer, assign, mortgage or pledge any property to or
with the Trustee or to surrender any right or power herein conferred upon the
Company; or

     (3)  to establish the form or terms of Securities of any series as
permitted by Sections 2.1 or 3.1; or

     (4)  to add to the covenants of the Company for the benefit of the Holders
of all or any series of Securities (and if such covenants are to be for the
benefit of less than all series of Securities, stating that such covenants are
expressly being included solely for the benefit of such series) or to surrender
any right or power herein conferred upon the Company; or

     (5)  to add any additional Events of Default for the benefit of the Holders
of all or any series of Securities (and if such additional Events of Default are
to be for the benefit of less than all series of Securities, stating that such
additional Events of Default are expressly being included solely for the benefit
of such series); or

     (6)  to change or eliminate any of the provisions of this Indenture,
provided that any such change or elimination shall become effective only when
there is no Security Outstanding of any series created prior to the execution of
such supplemental indenture which is entitled to the benefit of such provision;
or

     (7)  to cure any ambiguity, to correct or supplement any provision herein
which may be defective or inconsistent with any other provision herein, or to
make any other provisions with respect to matters or questions arising under
this Indenture, provided that such action pursuant to this clause (7) shall not
adversely affect the interest of the Holders of Securities of any series in any
material respect or, in the case of the Securities of a series issued to a ONEOK
Capital Trust and for so long as any of the corresponding series of Preferred
Securities issued by such ONEOK Capital Trust shall remain outstanding, the
holders of such Preferred Securities; or

     (8)  to evidence and provide for the acceptance of appointment hereunder by
a successor Trustee with respect to the Securities of one or more series and to
add to or change any of the provisions of this Indenture as shall be necessary
to provide for or facilitate the administration of the trusts hereunder by more
than one Trustee, pursuant to the requirements of Section 6.11(b); or

     (9)  to comply with the requirements of the Commission in order to effect
or maintain the qualification of this Indenture under the Trust Indenture Act.

     Section 9.2    Supplemental Indentures with Consent of Holders.

     With the consent of the Holders of not less than a majority in principal
amount of the Outstanding Securities of each series affected by such
supplemental indenture, by Act of said Holders delivered to the Company and the
Trustee, the Company, when authorized by a Board Resolution, and the Trustee may
enter into an indenture or indentures supplemental hereto for the purpose of
adding any provisions to or changing in any manner or eliminating any of the
provisions of this Indenture or of modifying in any manner the rights of the
Holders of Securities of such series under this Indenture; provided, however,
that no such supplemental indenture shall, without the consent of the Holder of
each Outstanding Security affected thereby,

                                       53
<PAGE>

     (1)  except to the extent permitted by Section 3.11 or as otherwise
specified as contemplated by Section 2.1 or Section 3.1 with respect to the
deferral of the payment of interest on the Securities of any series, change the
Stated Maturity of the principal of, or any installment of interest (including
any Additional Interest) on, any Security, or reduce the principal amount
thereof or the rate of interest thereon or reduce any premium payable upon the
redemption thereof; or reduce the amount of principal of a Discount Security
that would be due and payable upon a declaration of acceleration of the Maturity
thereof pursuant to Section 5.2, or change the place of payment where, or the
coin or currency in which, any Security or interest thereon is payable, or
impair the right to institute suit for the enforcement of any such payment on or
after the Stated Maturity thereof (or, in the case of redemption, on or after
the Redemption Date), or

     (2)  reduce the percentage in principal amount of the Outstanding
Securities of any series, the consent of whose Holders is required for any such
supplemental indenture, or the consent of whose Holders is required for any
waiver of compliance with certain provisions of this Indenture or certain
defaults hereunder and their consequences provided for in this Indenture, or

     (3)  modify any of the provisions of this Section, Section 5.13 or Section
10.5, except to increase any such percentage or to provide that certain other
provisions of this Indenture cannot be modified or waived without the consent of
the Holder of each Security affected thereby; or

     (4)  modify the provisions in Article XIII of this Indenture with respect
to the subordination of Outstanding Securities of any series in a manner adverse
to the Holders thereof;

provided, further, that, in the case of the Securities of a series issued to a
ONEOK Capital Trust, so long as any of the corresponding series of Preferred
Securities issued by such ONEOK Capital Trust remains outstanding, (i) no such
amendment shall be made that adversely affects the holders of such Preferred
Securities in any material respect, and no termination of this Indenture shall
occur, and no waiver of any Event of Default or compliance with any covenant
under this Indenture shall be effective, without the prior consent of the
holders of a majority of the aggregate liquidation preference of such Preferred
Securities then outstanding unless and until the principal (and premium, if any)
of the Securities of such series and all accrued and, subject to Section 3.7,
unpaid interest (including any Additional Interest) thereon have been paid in
full and (ii) no amendment shall be made to Section 5.8 of this Indenture that
would impair the rights of the holders of Preferred Securities provided therein
without the prior consent of the holders of each Preferred Security then
outstanding of such series unless and until the principal (and premium, if any)
of the Securities of such series and all accrued and (subject to Section 3.7)
unpaid interest (including any Additional Interest) thereon have been paid in
full.

     A supplemental indenture that changes or eliminates any covenant or other
provision of this Indenture that has expressly been included solely for the
benefit of one or more particular series of Securities or Preferred Securities,
or which modifies the rights of the Holders of Securities or holders of
Preferred Securities of such series with respect to such covenant or other
provision, shall be deemed not to affect the rights under this Indenture of the
Holders of Securities or holders of Preferred Securities of any other series.

                                       54
<PAGE>

     It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such Act shall approve the substance thereof.

     Section 9.3    Execution of Supplemental Indentures.

     In executing or accepting the additional trusts created by any supplemental
indenture permitted by this Article or the modifications thereby of the trusts
created by this Indenture, the Trustee shall be entitled to receive, and
(subject to Section 6.1) shall be fully protected in relying upon, an Officers'
Certificate and an Opinion of Counsel of the Company stating that the execution
of such supplemental indenture is authorized or permitted by this Indenture, and
that all conditions precedent have been complied with.  The Trustee may, but
shall not be obligated to, enter into any such supplemental indenture which
affects the Trustee's own rights, duties or immunities under this Indenture or
otherwise.

     Section 9.4    Effect of Supplemental Indentures.

     Upon the execution of any supplemental indenture under this Article, this
Indenture shall be modified in accordance therewith, and such supplemental
indenture shall form a part of this Indenture for all purposes; and every Holder
of Securities theretofore or thereafter authenticated and delivered hereunder
shall be bound thereby.

     Section 9.5    Conformity with Trust Indenture Act.

     Every supplemental indenture executed pursuant to this Article shall
conform to the requirements of the Trust Indenture Act as then in effect.

     Section 9.6    Reference in Securities to Supplemental Indentures.

     Securities authenticated and delivered after the execution of any
supplemental indenture pursuant to this Article may, and shall if required by
the Company, bear a notation in form approved by the Company  as to any matter
provided for in such supplemental indenture.  If the Company shall so determine,
new Securities of any series so modified as to conform, in the opinion of the
Company, to any such supplemental indenture may be prepared and executed by the
Company and authenticated and delivered by the Trustee in exchange for
Outstanding Securities of such series.


                                   ARTICLE X

                                   COVENANTS

     Section 10.1   Payment of Principal, Premium and Interest.

     The Company covenants and agrees for the benefit of the Holders of each
series of Securities that it will duly and punctually pay the principal of (and
premium, if any) and interest and any other amounts payable on the Securities of
that series in accordance with the terms of such Securities and this Indenture.
Whenever in this Indenture or the Securities there is a reference in any context
to the

                                       55
<PAGE>

payment of interest on the Securities, such mention shall be deemed to include
payments of Additional Interest to the extent that Additional Interest is
payable on the Securities. Express mention of the payment of Additional Interest
(if applicable) in any provisions hereof shall not be construed as excluding
Additional Interest in those provisions hereof where such express mention is not
made.

     Section 10.2   Maintenance of Office or Agency.

     The Company will maintain in each Place of Payment for any series of
Securities, an office or agency where Securities of that series may be presented
or surrendered for payment and an office or agency where Securities of that
series may be surrendered for transfer or exchange and where notices and demands
to or upon the Company in respect of the Securities of that series and this
Indenture may be served.  The Company initially appoints the Trustee, acting
through its Corporate Trust Office, as its agent for said purposes.  The Company
will give prompt written notice to the Trustee of any change in the location of
any such office or agency.  If at any time the Company shall fail to maintain
such office or agency or shall fail to furnish the Trustee with the address
thereof; such presentations, surrenders, notices and demands may be made or
served at the Corporate Trust Office of the Trustee, and the Company hereby
appoints the Trustee as its agent to receive all such presentations, surrenders,
notices and demands.

     The Company may also from time to time designate one or more other offices
or agencies where the Securities may be presented or surrendered for any or all
of such purposes, and may from time to time rescind such designations; provided,
however, that no such designation or rescission shall in any manner relieve the
Company of its obligation to maintain an office or agency in each Place of
Payment for Securities of any series for such purposes.  The Company will give
prompt written notice to the Trustee of any such designation and any change in
the location of any such office or agency.

     Section 10.3   Money or Security Payments to be Held in Trust.

     If the Company shall at any time act as its own Paying Agent with respect
to any series of Securities, it will, on or before each due date of the
principal of (and premium, if any) or interest on any of the Securities of such
series, segregate and hold in trust for the benefit of the Persons entitled
thereto a sum sufficient to pay the principal (and premium, if any) or interest
so becoming due until such sums shall be paid to such Persons or otherwise
disposed of as herein provided, and will promptly notify the Trustee of its
failure so to act.

     Whenever the Company shall have one or more Paying Agents, it will, prior
to 10:00 a.m. New York City time on each due date of the principal of or
interest on any Securities, deposit with a Paying Agent a sum sufficient to pay
the principal (and premium, if any) or interest so becoming due, such sum to be
held in trust for the benefit of the Persons entitled to such principal and
premium (if any) or interest, and (unless such Paying Agent is the Trustee) the
Company will promptly notify the Trustee of its failure so to act.

     The Company will cause each Paying Agent other than the Trustee to execute
and deliver to the Trustee an instrument in which such Paying Agent shall agree
with the Trustee, subject to the provisions of this Section, that such Paying
Agent will:

                                       56
<PAGE>

     (1)  hold all sums held by it for the payment of the principal of (and
premium, if any) or interest on Securities in trust for the benefit of the
Persons entitled thereto until such sums shall be paid to such Persons or
otherwise disposed of as herein provided;

     (2)  give the Trustee notice of any default by the Company (or any other
obligor upon the Securities) in the making of any payment of principal (and
premium, if any) or interest;

     (3)  at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held in
trust by such Paying Agent; and

     (4)  comply with the provisions of the Trust Indenture Act applicable to it
as a Paying Agent.

     The Company may at any time, for the purpose of obtaining the satisfaction
and discharge of this Indenture or for any other purpose, pay, or by Company
Order direct any Paying Agent to pay, to the Trustee all sums held in trust by
the Company or such Paying Agent, such sums to be held by the Trustee upon the
same trusts as those upon which such sums were held by the Company or such
Paying Agent; and, upon such payment by any Paying Agent to the Trustee, such
Paying Agent shall be released from all further liability with respect to such
money.

     Any money deposited with the Trustee or any Paying Agent, or then held by
the Company, in trust for the payment of the principal of (and premium, if any)
or interest on any Security and remaining unclaimed for two years after such
principal (and premium, if any) or interest has become due and payable shall
(unless otherwise required by mandatory provision of applicable escheat or
abandoned or unclaimed property law) be paid on Company Request to the Company,
or (if then held by the Company) shall (unless otherwise required by mandatory
provision of applicable escheat or abandoned or unclaimed property law) be
discharged from such trust; and the Holder of such Security shall thereafter, as
an unsecured general creditor, look only to the Company for payment thereof; and
all liability of the Trustee or such Paying Agent with respect to such trust
money, and all liability of the Company as trustee thereof; shall thereupon
cease; provided, however, that the Trustee or such Paying Agent, before being
required to make any such repayment, may at the expense of the Company cause to
be published once, in a newspaper published in the English language, customarily
published on each Business Day and of general circulation in the Borough of
Manhattan, The City of New York, notice that such money remains unclaimed and
that, after a date specified therein, which shall not be less than 30 days from
the date of such publication, any unclaimed balance of such money then remaining
will be repaid to the Company.

     Section 10.4   Statement as to Compliance.

     The Company shall deliver to the Trustee, within 120 days after the end of
each calendar year ending after the date hereof; an Officers' Certificate
complying with Section 314(a)(4) of the Trust Indenture Act and covering the
preceding calendar year, stating whether or not to the best knowledge of the
signers thereof the Company is in default in the performance, observance or
fulfillment of or compliance with any of the terms, provisions, covenants and
conditions of this Indenture, and if the Company shall be in default, specifying
all such defaults and the nature and status thereof of which they may have
knowledge.  For the purpose of this Section 10.4, compliance shall be determined

                                       57
<PAGE>

without regard to any grace period or requirement of notice provided pursuant to
the terms of this Indenture.

     Section 10.5   Waiver of Certain Covenants.

     The Company may omit in any particular instance to comply with any covenant
or condition provided pursuant to Section 3.1, 9.1(3) or 9.1(4) with respect to
the Securities of any series, if before or after the time for such compliance
the Holders of at least a majority in principal amount of the Outstanding
Securities of such series shall, by Act of such Holders, either waive such
compliance in such instance or generally waive compliance with such covenant or
condition, but no such waiver shall extend to or affect such covenant or
condition except to the extent so expressly waived, and, until such waiver shall
become effective, the obligations of the Company in respect of any such covenant
or condition shall remain in full force and effect.

     Section 10.6   Additional Sums.

     In the case of the Securities of a series issued to a ONEOK Capital Trust,
so long as no Event of Default has occurred and is continuing and except as
otherwise specified as contemplated by Section 2.1 or Section 3.1, in the event
that (i) a ONEOK Capital Trust is the Holder of all of the Outstanding
Securities of such series, (ii) a Tax Event in respect of such ONEOK Capital
Trust shall have occurred and be continuing and (iii) the Company shall not have
(A) redeemed the Securities of such series pursuant to Section 11.7(b) or (B)
terminated such ONEOK Capital Trust pursuant to Section 9.2(b) of the related
Trust Agreement, the Company shall pay to such ONEOK Capital Trust (and its
permitted successors or assigns under the related Trust Agreement) for so long
as such ONEOK Capital Trust (or its permitted successor or assignee) is the
registered holder of any Securities of such series, such additional amounts as
may be necessary in order that the amount of Distributions (including any
Additional Amounts (as defined in such Trust Agreement)) then due and payable by
such ONEOK Capital Trust on the related Preferred Securities and Common
Securities that at any time remain outstanding in accordance with the terms
thereof shall not be reduced as a result of any Additional Taxes (the
"Additional Sums").  Whenever in this Indenture or the Securities there is a
reference in any context to the payment of principal of, premium, if any, or
interest on the Securities, such mention shall be deemed to include mention of
the payments of the Additional Sums provided for in this paragraph to the extent
that, in such context, Additional Sums are, were or would be payable in respect
thereof pursuant to the provisions of this paragraph and express mention of the
payment of Additional Sums (if applicable) in any provisions hereof shall not be
construed as excluding Additional Sums in those provisions hereof where such
express mention is not made; provided, however, that the deferral of the payment
of interest pursuant to Section 3.11 or the Securities shall not defer the
payment of any Additional Sums that may be due and payable.

     Section 10.7   Additional Covenants.

     The Company covenants and agrees with each Holder of Securities of each
series that it shall not, (a) declare or pay any dividends or distributions on,
or redeem purchase, acquire or make a liquidation payment with respect to, any
shares of the its capital stock, or (b) make any payment of principal of or
interest or premium, if any, on or repay, repurchase or redeem any debt
securities issued by it that rank pari passu with or junior in interest to the
Securities of such series or make any guarantee payments with respect to any
guarantee by the Company of debt securities of any

                                       58
<PAGE>

Subsidiary of the Company if such guarantee ranks pari passu with or junior in
interest to the Securities (other than (a) dividends or distributions in Common
Stock, (b) any declaration of a dividend in connection with the implementation
of a Rights Plan, the issuance of any rights, of any Common Stock or any class
or series of preferred stock of the Company or of any other property under any
Rights Plan or the repurchase of any rights distributed pursuant to a Rights
Plan, (c) payments under any ONEOK Capital Guarantee, and (d) purchases of
Common Stock related to the issuance of Common Stock under any of the Company's
benefit plans for its directors, officers or employees), if at such time (i)
there shall have occurred any event of which the Company has actual knowledge
that (A) with the giving of notice or the lapse of time or both, would
constitute an Event of Default with respect to the Securities of such series and
(B) in respect of which the Company shall have not taken reasonable steps to
cure, (ii) if the Securities of such series are held by a ONEOK Capital Trust,
the Company shall be in default with respect to its payment of any obligations
under the ONEOK Capital Guarantee relating to the Preferred Securities issued by
such ONEOK Capital Trust or (iii) the Company shall have given notice of its
election to begin an Extension Period with respect to the Securities of such
series as provided herein and shall not have rescinded such notice, or such
Extension Period, or any extension thereof, shall be continuing.

     The Company also covenants with each Holder of Securities of a series
issued to a ONEOK Capital Trust (i) to maintain directly or indirectly 100%
ownership of the Common Securities of such ONEOK Capital Trust; provided,
however, that any permitted successor of the Company hereunder may succeed to
the Company's ownership of such Common Securities, (ii) not to voluntarily
terminate, wind-up or liquidate such ONEOK Capital Trust, except (a) in
connection with a distribution of the Securities of such series to the holders
of Preferred Securities in liquidation of such ONEOK Capital Trust or (b) in
connection with certain mergers, consolidations or amalgamations permitted by
the related Trust Agreement and (iii) to use its reasonable efforts, consistent
with the terms and provisions of such Trust Agreement, to cause such ONEOK
Capital Trust to remain classified as a grantor trust and not an association
taxable as a corporation for United States federal income tax purposes.


                                  ARTICLE XI

                           REDEMPTION OF SECURITIES

     Section 11.1   Applicability of This Article.

     Redemption of Securities of any series (whether by operation of a sinking
fund or otherwise) as permitted or required by any form of Security issued
pursuant to this Indenture shall be made in accordance with such form of
Security and this Article; provided, however, that if any provision of any such
form of Security shall conflict with any provision of this Article, the
provision of such form of Security shall govern.  Except as otherwise set forth
in the form of Security of a particular series, each Security of such series
which is redeemed in part shall be subject to redemption only in the amount of
$25 or integral multiples thereof.

                                       59
<PAGE>

     Section 11.2   Election to Redeem; Notice to Trustee.

     The election of the Company to redeem any Securities shall be evidenced by
or pursuant to a Board Resolution.  In case of any redemption at the election of
the Company of less than all of the Securities of any particular series and
having the same terms, the Company shall, not less than 30 nor more than 60 days
prior to the Redemption Date (unless a shorter notice shall be satisfactory to
the Trustee), notify the Trustee of such date and of the principal amount of
Securities of that series to be redeemed.  In the case of any redemption of
Securities prior to the expiration of any restriction on such redemption
provided in the terms of such Securities, the Company shall furnish the Trustee
with an Officers' Certificate and an Opinion of Counsel evidencing compliance
with such restriction.

     Section 11.3   Selection of Securities to be Redeemed.

     If less than all the Securities of any series are to be redeemed (unless
all the Securities of such series and of a specified tenor are to be redeemed or
unless such redemption affects only a single Security), the particular
Securities to be redeemed shall be selected not more than 60 days prior to the
Redemption Date by the Trustee, from the Outstanding Securities of such series
not previously called for redemption, by such method as the Trustee shall deem
fair and appropriate and which may provide for the selection for redemption of a
portion of the principal amount of any Security of such series, provided that
the unredeemed portion of the principal amount of any Security shall be in an
authorized denomination (which shall not be less than the minimum authorized
denomination) for such Security.  If less than all the Securities of such series
and of a specified tenor are to be redeemed (unless such redemption affects only
a single Security), the particular Securities to be redeemed shall be selected
not more than 60 days prior to the Redemption Date by the Trustee, from the
Outstanding Securities of such series and specified tenor not previously called
for redemption in accordance with the preceding sentence.

     The Trustee shall promptly notify the Company in writing of the Securities
selected for partial redemption and the principal amount thereof to be redeemed.
For all purposes of this Indenture, unless the context otherwise requires, all
provisions relating to the redemption of Securities shall relate, in the case of
any Security redeemed or to be redeemed only in part, to the portion of the
principal amount of such Security which has been or is to be redeemed.  If the
Company shall so direct, Securities registered in the name of the Company, any
Affiliate or any Subsidiary thereof shall not be included in the Securities
selected for redemption.

     Section 11.4   Notice of Redemption.

     Notice of redemption shall be given by first-class mail, postage prepaid,
mailed not later than the thirtieth day, and not earlier than the sixtieth day,
prior to the Redemption Date, to each Holder of Securities to be redeemed, at
the address of such Holder as it appears in the Securities Register.

     With respect to Securities of each series to be redeemed, each notice of
redemption shall state:

     (a)  the Redemption Date;

     (b)  the Redemption Price;

                                       60
<PAGE>

     (c)  if less than all Outstanding Securities of such particular series and
having the same terms are to be redeemed, the identification (and, in the case
of partial redemption, the respective principal amounts) of the particular
Securities to be redeemed;

     (d)  that on the Redemption Date, the Redemption Price will become due and
payable upon each such Security or portion thereof; and that interest thereon,
if any, shall cease to accrue on and after said date;

     (e)  the place or places where such Securities are to be surrendered for
payment of the Redemption Price; and

     (f)  that the redemption is for a sinking fund, if such is the case.

     Notice of redemption of Securities to be redeemed at the election of the
Company shall be given by the Company or, at the Company's request, by the
Trustee in the name and at the expense of the Company and shall not be
revocable.  The notice if mailed in the manner herein provided shall be
conclusively presumed to have been duly given, whether or not the Holder
receives such notice. In any case, a failure to give such notice by mail or any
defect in the notice to the Holder of any Security designated for redemption as
a whole or in part shall not affect the validity of the proceedings for the
redemption of any other Security.

     Section 11.5  Deposit of Redemption Price.

     Prior to 10:00 a.m.  New York City time on the Redemption Date specified in
the notice of redemption given as provided in Section 11.4, the Company will
deposit with the Trustee or with one or more Paying Agents (or if the Company is
acting as its own Paying Agent, the Company will segregate and hold in trust as
provided in Section 10.3) an amount of money sufficient to pay the Redemption
Price of; and any accrued interest (including Additional Interest) on, all the
Securities which are to be redeemed on that date.

     Section 11.6  Payment of Securities Called for Redemption.

     If any notice of redemption has been given as provided in Section 11.4, the
Securities or portion of Securities with respect to which such notice has been
given shall become due and payable on the date and at the place or places stated
in such notice at the applicable Redemption Price.  On presentation and
surrender of such Securities at a Place of Payment in said notice specified, the
said securities or the specified portions thereof shall be paid and redeemed by
the Company at the applicable Redemption Price, together with accrued interest
(including any Additional Interest) to the Redemption Date; provided, however,
that, unless otherwise specified as contemplated by Section 3.1, installments of
interest whose Stated Maturity is on or prior to the Redemption Date will be
payable to the Holders of such Securities, or one or more Predecessor
Securities, registered as such at the close of business on the relevant Record
Dates according to their terms and the provisions of Section 3.7.

     Upon presentation of any Security redeemed in part only, the Company shall
execute and the Trustee shall authenticate and deliver to the Holder thereof, at
the expense of the Company, a new Security or Securities of the same series, of
authorized denominations, in aggregate principal amount

                                       61
<PAGE>

equal to the unredeemed portion of the Security so presented and having the same
Original Issue Date, Stated Maturity and terms. If a Global Security is so
surrendered, such new Security will also be a new Global Security.

     If any Security called for redemption shall not be so paid upon surrender
thereof for redemption, the principal of and premium, if any, on such Security
shall, until paid, bear interest from the Redemption Date at the rate prescribed
therefor in the Security.

     Section 11.7  Right of Redemption of Securities Initially Issued to a ONEOK
Capital Trust.

     In the case of the Securities of a series initially issued to a ONEOK
Capital Trust, except as otherwise specified as contemplated by Section 3.1, the
Company, at its option, may redeem such Securities (i) on or after the date five
years after the Original Issue Date of such Securities, in whole at any time or
in part from time to time, or (ii) upon the occurrence and during the
continuation of a Special Event, at any time within 90 days following the
occurrence of such Special Event in respect of such ONEOK Capital Trust, in
whole (but not in part), in each case at a Redemption Price equal to 100% of the
principal amount thereof.


                                   ARTICLE XII

                                 SINKING FUNDS

     Section 12.1  Applicability of Article.

     The provisions of this Article shall be applicable to any sinking fund for
the retirement of Securities of any series except as otherwise specified as
contemplated by Section 3.1 for such Securities.

     The minimum amount of any sinking fund payment provided for by the terms of
any Securities of any series is herein referred to as a "mandatory sinking fund
payment", and any sinking fund payment in excess of such minimum amount which is
permitted to be made by the terms of such Securities of any series is herein
referred to as an "optional sinking fund payment".  If provided for by the terms
of any Securities of any series, the cash amount of any sinking fund payment may
be subject to reduction as provided in Section 12.2.  Each sinking fund payment
shall be applied to the redemption of Securities of any series as provided for
by the terms of such Securities.

     Section 12.2  Satisfaction of Sinking Fund Payments with Securities.

     In lieu of making all or any part of a mandatory sinking fund payment with
respect to any Securities of a series in cash, the Company may at its option, at
any time no more than 16 months and no less than 30 days prior to the date on
which such sinking fund payment is due, deliver to the Trustee Securities of
such series (together with the unmatured coupons, if any, appertaining thereto)
theretofore purchased or otherwise acquired by the Company, or credit securities
previously canceled or otherwise delivered to the Trustee for cancellation,
except Securities of such series that have been redeemed through the application
of mandatory or optional sinking fund payments pursuant to the terms of the
Securities of such series, accompanied by a Company Order instructing the
Trustee to

                                       62
<PAGE>

cancel such Securities if not previously canceled or credit such obligations and
stating that the Securities of such series were originally issued by the Company
by way of bona fide sale or other negotiation for value; provided that the
Securities to be so credited have not been previously so credited. The
Securities to be so credited shall be received and credited for such purpose by
the Trustee at the Redemption Price for such Securities, as specified in the
Securities so to be redeemed, for redemption through operation of the sinking
fund and the amount of such sinking fund payment shall be reduced accordingly.

     Section 12.3  Redemption of Securities for Sinking Fund.

     Not less than 60 days prior to each sinking fund payment date for any
series of Securities, the Company will deliver to the Trustee an Officers'
Certificate specifying the amount of the next ensuing sinking fund payment for
such Securities pursuant to the terms of such Securities, the portion thereof;
if any, which is to be satisfied by payment of cash in the currency in which the
Securities of such series are payable (except as provided pursuant to Section
3.1) and the portion thereof; if any, which is to be satisfied by delivering and
crediting Securities pursuant to Section 12.2 and will also deliver to the
Trustee any Securities to be so delivered.  Such Officers' Certificate shall be
irrevocable and upon its delivery the Company shall be obligated to make the
cash payment or payments therein referred to, if any, on or before the
succeeding sinking fund payment date.  In the case of the failure of the Company
to deliver such Officers' Certificate (or, as required by this Indenture, the
Securities and coupons, if any, specified in such Officers' Certificate), the
sinking fund payment due on the succeeding sinking fund payment date for such
series shall be paid entirely in cash and shall be sufficient to redeem the
principal amount of the Securities of such series subject to a mandatory sinking
fund payment without the right to deliver or credit securities as provided in
Section 12.2 and without the right to make the optional sinking fund payment
with respect to such series at such time.

     Any sinking fund payment or payments (mandatory or optional) made in cash
plus any unused balance of any preceding sinking fund payments made with respect
to the Securities of any particular series shall be applied by the Trustee (or
by the Company if the Company is acting as its own Paying Agent) on the sinking
fund payment date on which such payment is made (or, if such payment is made
before a sinking fund payment date, on the sinking fund payment date immediately
following the date of such payment) to the redemption of Securities of such
series at the Redemption Price specified in such Securities with respect to the
sinking fund.  Any sinking fund moneys not so applied or allocated by the
Trustee (or, if the Company is acting as its own Paying Agent, segregated and
held in trust by the Company as provided in Section 10.3) for such series and
together with such payment (or such amount so segregated) shall be applied in
accordance with the provisions of this Section 12.3.  Any and all sinking fund
moneys with respect to the Securities of any particular series held by the
Trustee (or if the Company is acting as its own Paying Agent, segregated and
held in trust as provided in Section 10.3) on the last sinking fund payment date
with respect to Securities of such series and not held for the payment or
redemption of particular Securities of such series shall be applied by the
Trustee (or by the Company if the Company is acting as its own Paying Agent),
together with other moneys, if necessary, to be deposited (or segregated)
sufficient for the purpose, to the payment of the principal of the Securities of
such series at Maturity.  The Trustee shall select the Securities to be redeemed
upon such sinking fund payment date in the manner specified in Section 11.3 and
cause notice of the redemption thereof to be given in the name of and at the
expense of the Company in the manner provided in Section 11.4.  Such notice
having been duly given, the redemption of such Securities shall be made upon the
terms and in the manner stated in Section 11.6.  On or before each

                                       63
<PAGE>

sinking fund payment date, the Company shall pay to the Trustee (or, if the
Company is acting as its own Paying Agent, the Company shall segregate and hold
in trust as provided in Section 10.3) in cash a sum in the currency in which
Securities of such series are payable (except as provided pursuant to Section
3.1) equal to the principal and any interest accrued to the Redemption Date for
Securities or portions thereof to be redeemed on such sinking fund payment date
pursuant to this Section 12.3.

     Neither the Trustee nor the Company shall redeem any Securities of a series
with sinking fund moneys or mail any notice of redemption of Securities of such
series by operation of the sinking fund for such series during the continuance
of a default in payment of interest, if any, on any Securities of such series or
of any Event of Default (other than an Event of Default occurring as a
consequence of this paragraph) with respect to the Securities of such series,
except that if the notice of redemption shall have been provided in accordance
with the provisions hereof; the Trustee (or the Company, if the Company is then
acting as its own Paying Agent) shall redeem such Securities if cash sufficient
for that purpose shall be deposited with the Trustee (or segregated by the
Company) for that purpose in accordance with the terms of this Article XII.
Except as aforesaid, any moneys in the sinking fund for such series at the time
when any such default or Event of Default shall occur and any moneys thereafter
paid into such sinking fund shall, during the continuance of such default or
Event of Default, be held as security for the payment of the Securities and
coupons, if any, of such series; provided, however, that in case such default or
Event of Default shall have been cured or waived herein, such moneys shall
thereafter be applied on the next sinking fund payment date for the Securities
of such series on which such moneys may be applied pursuant to the provisions of
this Section 12.3.


                                   ARTICLE XII

                          SUBORDINATION OF SECURITIES

     Section 13.1  Securities Subordinate to Senior Debt.

     The Company covenants and agrees, and each Holder of a Security, by its
acceptance thereof, likewise covenants and agrees, that, to the extent and in
the manner hereinafter set forth in this Article, the payment of the principal
of (and premium, if any) and interest (including any Additional Interest) on
each and all of the Securities are hereby expressly made subordinate and subject
in right of payment to the prior payment in full of all Senior Debt of the
Company.

     Section 13.2  Payment Over of Proceeds Upon Dissolution, Etc.

     In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company (each such event, if any, herein
sometimes referred to as a "Proceeding"), then the holders of Senior Debt of the
Company shall be entitled to receive payment in full of all Allocable Amounts of
such Senior Debt, or provision shall be made for such payment in cash or cash
equivalents or otherwise in a manner satisfactory to the holders of Senior Debt
of the Company before the Holders of the Securities are entitled to receive or
retain any payment or distribution of any kind or character, whether in cash,
property or securities (including any payment or distribution which may be
payable or deliverable by reason of the payment of any other Debt of the Company
(including any series of

                                       64
<PAGE>

the Securities) subordinated to the payment of the Securities, such payment or
distribution being hereinafter referred to as a "Junior Subordinated Payment"),
on account of principal of (or premium, if any) or interest (including any
Additional Interest) on the Securities or on account of the purchase or other
acquisition of Securities by the Company and to that end the holders of Senior
Debt of the Company shall be entitled to receive, for application to the payment
thereof; any payment or distribution of any kind or character, whether in cash,
property or securities, including any Junior Subordinated Payment, which may be
payable or deliverable in respect of the Securities in any such Proceeding.

     In the event that, notwithstanding the foregoing provisions of this
Section, the Trustee or the Holder of any Security shall have received any
payment or distribution of assets of the Company of any kind or character,
whether in cash, property or securities, including any Junior Subordinated
Payment, before all Allocable Amounts of all Senior Debt of the Company are paid
in full or payment thereof is provided for in cash or cash equivalents or
otherwise in a manner satisfactory to the holders of Senior Debt of the Company,
and if such fact shall, at or prior to the time of such payment or distribution,
have been made known to the Trustee or, as the case may be, such Holder, then
and in such event such payment or distribution shall be paid over or delivered
forthwith to the trustee in bankruptcy, receiver, liquidating trustee,
custodian, assignee, agent or other Person making payment or distribution of
assets of the Company for application to the payment of all Allocable Amounts of
all Senior Debt of the Company remaining unpaid, to the extent necessary to pay
all Allocable Amounts of all Senior Debt of the Company in full, after giving
effect to any concurrent payment or distribution to or for the holders of Senior
Debt of the Company.

     For purposes of this Article only, the words "any payment or distribution
of any kind or character, whether in cash, property or securities" shall not be
deemed to include shares of stock of the Company as reorganized or readjusted,
or securities of the Company or any other corporation provided for by a plan of
reorganization or readjustment which securities are subordinated in right of
payment to all then outstanding Senior Debt of the Company to substantially the
same extent as the Securities are so subordinated as provided in this Article.
The consolidation of the Company with, or the merger of the Company into,
another Person or the liquidation or dissolution of the Company following the
sale of all or substantially all of its properties and assets as an entirety to
another Person upon the terms and conditions set forth in Article VIII shall not
be deemed a Proceeding for the purposes of this Section if the Person formed by
such consolidation or into which the Company is merged or the Person which
acquires by sale such properties and assets as an entirety, as the case may be,
shall, as a part of such consolidation, merger, or sale comply with the
conditions set forth in Article VIII.

     Section 13.3  Prior Payment to Senior Debt Upon Acceleration of Securities.

     In the event that any Securities are declared due and payable before their
Stated Maturity, then and in such event the holders of the Senior Debt of the
Company outstanding at the time such Securities so become due and payable shall
be entitled to receive payment in full of all Allocable Amounts due on or in
respect of such Senior Debt (including any amounts due upon acceleration), or
provision shall be made for such payment in cash or cash equivalents or
otherwise in a manner satisfactory to the holders of Senior Debt of the Company
before the Holders of the Securities are entitled to receive any payment or
distribution of any kind or character, whether in cash, properties or securities
(including any Junior Subordinated Payment) by the Company on account of the

                                       65
<PAGE>

principal of (or premium, if any) or interest (including any Additional
Interest) on the Securities or on account of the purchase or other acquisition
of Securities by the Company ; provided, however, that nothing in this Section
shall prevent the satisfaction of any sinking fund payment in accordance with
this Indenture or as otherwise specified as contemplated by Section 3.1 for the
Securities of any series by delivering and crediting pursuant to Section 12.2 or
as otherwise specified as contemplated by Section 3.1 for the Securities of any
series Securities which have been acquired (upon redemption or otherwise) prior
to such declaration of acceleration.

     In the event that, notwithstanding the foregoing, the Company shall make
any payment to the Trustee or the Holder of any Security prohibited by the
foregoing provisions of this Section, and if such fact shall, at or prior to the
time of such payment, have been made known to the Trustee or, as the case may
be, such Holder, then and in such event such payment shall be paid over and
delivered forthwith to the Company.

     The provisions of this Section shall not apply to any payment with respect
to which Section 13.2 would be applicable.

     Section 13.4  No Payment When Senior Debt in Default.

     (a)  In the event and during the continuation of any default in the payment
of principal of (or premium, if any) or interest on any Senior Debt of the
Company, or in the event that any event of default with respect to any Senior
Debt of the Company shall have occurred and be continuing and shall have
resulted in such Senior Debt becoming or being declared due and payable prior to
the date on which it would otherwise have become due and payable, unless and
until such event of default shall have been cured or waived or shall have ceased
to exist and such acceleration shall have been rescinded or annulled, or (b) in
the event any judicial proceeding shall be pending with respect to any such
default in payment or such event or default, then no payment or distribution of
any kind or character, whether in cash, properties or securities (including any
Junior Subordinated Payment) shall be made by the Company on account of
principal of (or premium, if any) or interest (including any Additional
Interest), if any, on the Securities or on account of the purchase or other
acquisition of Securities by the Company, in each case unless and until all
Allocable Amounts of such Senior Debt are paid in full; provided, however, that
nothing in this Section shall prevent the satisfaction of any sinking fund
payment in accordance with this Indenture or as otherwise specified as
contemplated by Section 3.1 for the Securities of any series by delivering and
crediting pursuant to Section 12.2 or as otherwise specified as contemplated by
Section 3.1 for the Securities of any series Securities which have been acquired
(upon redemption or otherwise) prior to such default in payment or event of
default.

     In the event that, notwithstanding the foregoing, the Company shall make
any payment to the Trustee or the Holder of any Security prohibited by the
foregoing provisions of this Section, and if such fact shall, at or prior to the
time of such payment, have been made known to the Trustee or, as the case may
be, such Holder, then and in such event such payment shall be paid over and
delivered forthwith to the Company.

     The provisions of this Section shall not apply to any payment with respect
to which Section 13.2 would be applicable.

                                       66
<PAGE>

     Section 13.5  Payment Permitted If No Default.

     Nothing contained in this Article or elsewhere in this Indenture or in any
of the Securities shall prevent (a) the Company at any time except during the
pendency of any Proceeding with respect to it referred to in Section 13.2 or
under the conditions described in Sections 13.3 and 13.4, from making payments
at any time of principal of (and premium, if any) or interest (including
Additional Interest) on the Securities or (b) the application by the Trustee of
any money deposited with it hereunder to the payment of or on account of the
principal of (and premium, if any) or interest (including any Additional
Interest) on the Securities or the retention of such payment by the Holders, if,
at the time of such application by the Trustee, it did not have knowledge that
such payment would have been prohibited by the provisions of this Article.

     Section 13.6  Subrogation to Rights of Holders of Senior Debt.

     Subject to the payment in full of all amounts due or to become due on all
Senior Debt of the Company or the provision for such payment in cash or cash
equivalents or otherwise in a manner satisfactory to the holders of Senior Debt
of the Company the Holders of the Securities shall be subrogated to the extent
of the payments or distributions made to the holders of such Senior Debt
pursuant to the provisions of this Article (equally and ratably with the holders
of all indebtedness of the Company which by its express terms is subordinated to
Senior Debt of the Company to substantially the same extent as the Securities
are subordinated to the Senior Debt of the Company and is entitled to like
rights of subrogation by reason of any payments or distributions made to holders
of such Senior Debt) to the rights of the holders of such Senior Debt to receive
payments and distributions of cash, property and securities applicable to the
Senior Debt of the Company until the principal of (and premium, if any) and
interest on the Securities shall be paid in full.  For purposes of such
subrogation, no payments or distributions to the holders of the Senior Debt of
the Company of any cash, property or securities to which the Holders of the
Securities or the Trustee would be entitled except for the provisions of this
Article, and no payments over pursuant to the provisions of this Article to the
holders of Senior Debt of the Company by Holders of the Securities or the
Trustee, shall, as among the Company its creditors other than holders of its
Senior Debt, and the Holders of the Securities, be deemed to be a payment or
distribution by the Company to or on account of its Senior Debt.

     Section 13.7  Provisions Solely to Define Relative Rights.

     The provisions of this Article are and are intended solely for the purpose
of defining the relative rights of the Holders of the Securities on the one hand
and the holders of Senior Debt of the Company on the other hand.  Nothing
contained in this Article or elsewhere in this Indenture or in the Securities is
intended to or shall (a) impair, as between the Company and the Holders of the
Securities, the obligations of the Company, which are absolute and
unconditional, to pay to the Holders of the Securities the principal of (and
premium, if any) and interest (including any Additional Interest) on the
Securities as and when the same shall become due and payable in accordance with
their terms; or (b) affect the relative rights against the Company of the
Holders of the Securities and creditors of the Company other than their rights
in relation to the holders of Senior Debt of the Company; or (c) prevent the
Trustee or the Holder of any Security from exercising all remedies otherwise
permitted by applicable law upon default under this Indenture including, without
limitation, filing and voting claims in any Proceeding with respect to the
Company subject to the rights, if any,

                                       67
<PAGE>

under this Article of the holders of Senior Debt with respect to the Company to
receive cash, property and securities otherwise payable or deliverable to the
Trustee or such Holder.

     Section 13.8  Trustee to Effectuate Subordination.

     Each Holder of a Security by his or her acceptance thereof authorizes and
directs the Trustee on his or her behalf to take such action as may be necessary
or appropriate to acknowledge or effectuate the subordination provided in this
Article and appoints the Trustee his or her attorney-in-fact for any and all
such purposes.

     Section 13.9  No Waiver of Subordination Provisions.

     No right of any present or future holder of any Senior Debt with respect to
the Company to enforce subordination as herein provided shall at any time in any
way be prejudiced or impaired by any act or failure to act on the part of the
Company or by any act or failure to act, in good faith, by any such holder, or
by any noncompliance by the Company with the terms, provisions and covenants of
this Indenture, regardless of any knowledge thereof that any such holder may
have or be otherwise charged with.

     Without in any way limiting the generality of the immediately preceding
paragraph, the holders of Senior Debt with respect to the Company may, at any
time and from to time, without the consent of or notice to the Trustee or the
Holders of the Securities, without incurring responsibility to the Holders of
the Securities and without impairing or releasing the subordination provided in
this Article or the obligations hereunder of the Holders of the Securities to
the holders of such Senior Debt, do any one or more of the following: (i) change
the manner, place or terms of payment or extend the time of payment of, or renew
or alter, Senior Debt with respect to the Company or otherwise amend or
supplement in any manner Senior Debt with respect to the Company or any
instrument evidencing the same or any agreement under which Senior Debt with
respect to the Company is outstanding; (ii) sell, exchange, release or otherwise
deal with any property pledged, mortgaged or otherwise securing Senior Debt with
respect to the Company; (iii) release any Person liable in any manner for the
collection of Senior Debt with respect to the Company; and (iv) exercise or
refrain from exercising any rights against the Company and any other Person.

     Section 13.10 Notice to Trustee.

     The Company shall give prompt written notice to the Trustee of any fact
known to it which would prohibit the making of any payment to or by the Trustee
in respect of the Securities. Notwithstanding the provisions of this Article or
any other provision of this Indenture, the Trustee shall not be charged with
knowledge of the existence of any facts which would prohibit the making of any
payment to or by the Trustee in respect of the Securities, unless and until the
Trustee shall have received written notice thereof from the Company or a holder
of Senior Debt thereof or from any trustee, agent or representative therefor;
provided, however, that if the Trustee shall not have received the notice
provided for in this Section at least two Business Days prior to the date upon
which by the terms hereof any monies may become payable for any purpose
(including, without limitation, the payment of the principal of (and premium, if
any) or interest (including any Additional Interest) on any Security), then,
anything herein contained to the contrary notwithstanding, the Trustee shall
have full power and authority to receive such monies and to apply the same to
the

                                       68
<PAGE>

purpose for which they were received and shall not be affected by any notice
to the contrary which may be received by it within two Business Days prior to
such date.

     Subject to the provisions of Section 6.1, the Trustee shall be entitled to
rely on the delivery to it of a written notice by a Person representing himself
to be a holder of Senior Debt of the Company, (or a trustee therefor) to
establish that such notice has been given by a holder of Senior Debt of the
Company, (or a trustee therefor).  In the event that the Trustee determines in
good faith that further evidence is required with respect to the right of any
Person as a holder of Senior Debt of the Company to participate in any payment
or distribution pursuant to this Article, the Trustee may request such Person to
furnish evidence to the reasonable satisfaction of the Trustee as to the amount
of Senior Debt of the Company held by such Person, the extent to which such
Person is entitled to participate in such payment or distribution and any other
facts pertinent to the rights of such Person under this Article, and if such
evidence is not furnished, the Trustee may defer any payment to such Person
pending judicial determination as to the right of such Person to receive such
payment.

     Section 13.11  Reliance on Judicial Order or Certificate of Liquidating
Agent.

     Upon any payment or distribution of assets of the Company referred to in
this Article, the Trustee, subject to the provisions of Section 6.1, and the
Holders of the Securities shall be entitled to rely upon any order or decree
entered by any court of competent jurisdiction in which such Proceeding is
pending, or a certificate of the trustee in bankruptcy, receiver, liquidating
trustee, custodian, assignee for the benefit of creditors, agent or other Person
making such payment or distribution, delivered to the Trustee or to the Holders
of Securities, for the purpose of ascertaining the Persons entitled to
participate in such payment or distribution, the holders of the Senior Debt and
other indebtedness of the Company the amount thereof or payable thereon, the
amount or amounts paid or distributed thereon and all other facts pertinent
thereto or to this Article.

     Section 13.12  Trustee Not Fiduciary for Holders of Senior Debt.

     The Trustee, in its capacity as trustee under this Indenture, shall not be
deemed to owe any fiduciary duty to the holders of Senior Debt of the Company
and shall not be liable to any such holders if it shall in good faith mistakenly
pay over or distribute to Holders of Securities or to the Company, or to any
other Person cash, property or securities to which any holders of Senior Debt of
the Company shall be entitled by virtue of this Article or otherwise.

     Section 13.13  Rights of Trustee as Holder of Senior Debt; Preservation of
Trustee 's Rights.

     The Trustee in its individual capacity shall be entitled to all the rights
set forth in this Article with respect to any Senior Debt of the Company which
may at any time be held by it, to the same extent as any other holder of such
Senior Debt, and nothing in this Indenture shall deprive the Trustee of any of
its rights as such holder.  Nothing in this Article shall be construed to apply
to claims of the Trustee or any predecessor Trustee under Section 5.6 or 6.7.

     Section 13.14  Article Applicable to Paying Agents.

     In case at any time any Paying Agent other than the Trustee shall have been
appointed by the Company and be then acting hereunder, the term "Trustee" as
used in this Article shall in such case

                                       69
<PAGE>

(unless the context otherwise requires) be construed as extending to and
including such Paying Agent within its meaning as fully for all intents and
purposes as if such Paying Agent were named in this Article in addition to or in
place of the Trustee.

     Section 13.15  Certain Conversions or Exchanges Deemed Payment.

     For the purposes of this Article only, (a) the issuance and delivery of
junior securities upon conversion or exchange of Securities shall not be deemed
to constitute a payment or distribution on account of the principal of (or
premium, if any) or interest (including any Additional Interest) on Securities
or on account of the purchase or other acquisition of Securities, and (b) the
payment, issuance or delivery of cash, property or securities (other than junior
securities) upon conversion or exchange of a Security shall be deemed to
constitute payment on account of the principal of such security.  For the
purposes of this Section, the term "junior securities" means (i) shares of any
stock of any class of the Company and (ii) securities of the Company which are
subordinated in right of payment to all Senior Debt thereof which may be
outstanding at the time of issuance or delivery of such securities to
substantially the same extent as, or to a greater extent than, the Securities
are so subordinated as provided in this Article.

                                    * * * *

                                       70
<PAGE>

     This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

     IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed, and their respective corporate seals to be hereunto affixed and
attested, all as of the day and year first above written.

ONEOK, INC.



_______________________________
By:

Attest:



_______________________________

_______________________________

[__________]
as Trustee


_______________________________
By:

Attest:



_______________________________

                                       71

<PAGE>

                                                                   Exhibit 4.2
________________________________________________________________________________



                                  ONEOK, INC.

                                      and

                          __________________________,

                                  as Trustee



                         SUPPLEMENTAL INDENTURE NO. 1



                       Dated as of ______________, 1999



                             $___________________
                _____% Junior Subordinated Debentures due 20__


________________________________________________________________________________
<PAGE>

                                  ONEOK, INC.
                              $_________________
                 ___% Junior Subordinated Debentures due 20__

                         SUPPLEMENTAL INDENTURE NO. 1

     SUPPLEMENTAL INDENTURE No. 1, dated as of _____________, 1999 among ONEOK,
Inc., an Oklahoma corporation (the "Company"), and _______________________, a
national banking association duly organized and existing under the laws of the
United States, as Trustee (the "Trustee").


                                   RECITALS
                                   --------

     The Company and the Trustee have heretofore executed a Junior Subordinated
Indenture dated as of ______________, 1999 (the "Indenture"), providing for the
issuance from time to time of series of the Company's Securities.

     Section 3.1 of the Indenture provides for various matters with respect to
any series of Securities issued under the Indenture to be established in an
indenture supplemental to the Indenture.

     Section 9.1(3) of the Indenture provides for the Company and the Trustee to
enter into an indenture supplemental to the Indenture to establish the form or
terms of Securities of any series as provided by Section 2.1 or 3.1 of the
Indenture.

     For and in consideration of the premises and the issuance of the series of
Securities provided for herein, it is mutually covenanted and agreed, for the
equal and proportionate benefit of the Holders of the Securities of such series,
as follows:

                                   ARTICLE 1

                      RELATION TO INDENTURE; DEFINITIONS

     Section 1.1  This Supplemental Indenture No. 1 constitutes an integral
part of the Indenture.

     Section 1.2  For all purposes of this Supplemental Indenture No. 1:

     (1) Capitalized terms used herein without definition shall have the
meanings specified in the Indenture or in the Amended and Restated Trust
Agreement dated as of ___________, 1999, among the Company, as Depositor,
________________, as Property Trustee, _______________, as Delaware Trustee, and
the Administrative Trustee named therein, of ONEOK Capital Trust I, a Delaware
statutory business trust ("ONEOK Capital Trust I"), as the case may be;

     (2) All references herein to Articles and Sections, unless otherwise
specified, refer to the corresponding Articles and Sections of this Supplemental
Indenture No. 1; and
<PAGE>

     (3) The terms "herein", "hereof", "hereunder" and other words of similar
import refer to this Supplemental Indenture No. 1.

                                   ARTICLE 2

                           THE SERIES OF SECURITIES

     Section 2.1  Title of the Debt Securities.  There shall be a series of
                  ----------------------------
Debt Securities designated the "____% Junior Subordinated Debentures due 20__"
(the "Debt Securities").

     Section 2.2  Limitation on Aggregate Principal Amount; Date of Debt
                  ------------------------------------------------------
Securities.  The aggregate principal amount of the Debt Securities shall be
- ----------
limited to $_______________.  Each Debt Security shall be dated the date of its
authentication.

     Section 2.3  Principal Payment Date.  The principal amount of the Debt
                  ----------------------
Securities Outstanding (together with any accrued and unpaid interest (including
any Additional Interest) thereon) shall be payable in a single installment on
___________, 20__.

     Section 2.4  Interest and Interest Rates.  The rate of interest on each
                  ---------------------------
Debt Security shall be ____% per annum, accruing from ____________, 1999 and,
subject to Section 2.5, interest shall be payable, quarterly in arrears, on
___________, ___________, ___________ and ___________ of each year (each such
date, an "Interest Payment Date"), commencing _____________, 1999.  The rate of
any Additional Interest that shall accrue on each Debt Security shall be at the
same rate per annum.  The amount of interest payable for any period shall be
computed on the basis of a 360-day year of twelve 30-day months.  For any period
of less than a full month, interest payable shall reflect interest on the Debt
Securities computed on the basis of the actual number of elapsed days based on a
month of 30 days in a 360-day year.  In the event that any date on which
interest is payable on a Debt Security is not a Business Day, then a payment of
the interest payable on such date will be made on the next succeeding day which
is a Business Day (and without any interest or other payment in respect of any
such delay), except that, if such Business Day is in the next succeeding
calendar year, such payment shall be made on the immediately preceding Business
Day, in each case with the same force and effect as if made on the date such
payment was originally payable.  The interest installment so payable, and
punctually paid or duly provided for, on any Interest Payment Date shall be paid
to the Person in whose name such Debt Security (or one or more Predecessor
Securities) is registered in the Securities Register at the close of business on
the Regular Record Date for such interest installment, which, if such Debt
Security is a Global Security issued to the Depositary, shall be the close of
business on the Business Day next preceding such Interest Payment Date.  The
interest so payable on any Debt Security which is not punctually paid or duly
provided for on any Interest Payment Date shall forthwith cease to be payable to
the Holder on such Regular Record Date and may either be paid to the Person in
whose name such Debt Security (or one or more Predecessor Securities) is
registered in the Securities Register at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Trustee, notice whereof shall be given to Holders of Debt Securities not less
than 10 days prior to such Special Record Date, or be paid at any time in any
other lawful manner not inconsistent with the requirements of any securities
exchange on which the Debt Securities may be listed, and upon such notice as may
be required by such exchange, all as more fully provided in the Indenture.

                                       2
<PAGE>

     Section 2.5  Extension of Interest Payment Period.   (a) So long as no
                  ------------------------------------
Event of Default shall have occurred and be continuing, the Company shall have
the right, at any time during the term of the Debt Securities, from time to
time, to defer the payment of interest on the Debt Securities for up to [20]
consecutive quarters with respect to each deferred period (each, an "Extension
Period"), during which Extension Periods the Company shall have the right to
make partial payments of interest on any Interest Payment Date.  No Extension
Period shall end on a date other than an Interest Payment Date.  At the end of
any such Extension Period the Company shall pay all interest then accrued and
unpaid on the Debt Securities (together with Additional Interest thereon, if
any, at the annual rate of  ____%, compounded quarterly, to the extent permitted
by applicable law), provided, that no Extension Period shall extend beyond the
Maturity of the principal of the Debt Securities; provided, further, that during
any such Extension Period, the Company shall not (i) declare or pay any
dividends or distributions on, or redeem, purchase, acquire or make a
liquidation payment with respect to, any of its capital stock or (ii) make any
payment of principal of or interest or premium, if any, on or repay, repurchase
or redeem, any debt security issued by it that ranks pari passu with or junior
in interest to the Debt Securities or make any guarantee payments with respect
to any guaranty by the Company of the debt securities of any Subsidiary of the
Company that by their terms rank pari passu with or junior in interest to the
Debt Securities (other than (a) dividends or distributions in Common Stock, (b)
any declaration of a dividend in connection with the implementation of a Rights
Plan, the issuance of any Common Stock or any class or series of preferred stock
of the Company under any Rights Plan or the repurchase of any rights distributed
pursuant to a Rights Plan, (c) purchases of Common Stock related to the issuance
of Common Stock under any of the Company's benefit plans for their respective
directors, officers or employees).  Prior to the termination of any such
Extension Period, the Company may further extend the interest payment period.
Notwithstanding any provision of this Supplemental Indenture No. 1 or the
Indenture to the contrary, no Extension Period shall exceed [20] consecutive
quarters or extend beyond the Maturity of the Debt Securities.  Upon termination
of any such Extension Period and upon the payment of all accrued and unpaid
interest and any Additional Interest then due, the Company may elect to begin a
new Extension Period, subject to the requirements hereof.  No interest shall be
due and payable during an Extension Period, except at the end thereof.  The
Company shall give the Holders of the Debt Securities and the Property Trustee,
the Administrative Trustee and the Trustee notice of its election to begin or
extend any such Extension Period at least one Business Day prior to the earlier
of (i) the next succeeding date on which Distributions on the Preferred
Securities of ONEOK Capital Trust I would have been payable except for the
election to begin or extend such Extension Period or (ii) the date the
Administrative Trustee is required to give notice to any securities exchange or
other applicable self-regulatory organization or to holders of such Preferred
Securities of ONEOK Capital Trust I of the record date or the date such
Distributions are payable, but in any event not less than one Business Day prior
to such record date.  The Trustee shall promptly give notice of the Company's
election to begin or extend any such Extension Period to the holders of the
outstanding Debt Securities, and pursuant to Section 8.2 of the Trust Agreement,
within five Business Days following receipt of notice of the Company's election
to defer the payment of interest on the Debt Securities, the Administrative
Trustee shall notify the holders of the Preferred Securities of ONEOK Capital
Trust I and the Property Trustee of such election.

     Section 2.6  Place of Payment.  The Place of Payment where the Debt
                  ----------------
Securities may be presented or surrendered for payment, where the Debt
Securities may be surrendered for registration

                                       3
<PAGE>

of transfer or exchange and where notices and demands to or upon the Company in
respect of the Debt Securities and the Indenture may be served shall be the
Corporate Trust Office of the Trustee.

     Section 2.7  Redemption.  At any time on or after ___________, 20__, the
                  ----------
Company may, at its option, subject to the terms and conditions of Article XI of
the Indenture, redeem the Debt Securities in whole at any time or in part from
time to time, without premium or penalty, at a redemption price equal to 100% of
the principal amount thereof plus the accrued and unpaid interest, including
Additional Interest, if any, to the date fixed for redemption.

     If a Special Event in respect of ONEOK Capital Trust I shall occur and be
continuing, the Company may, at its option, redeem the Debt Securities within 90
days of the occurrence of such Special Event, in whole but not in part, subject
to the provisions of Article XI of the Indenture.  The redemption price for any
Debt Security so redeemed shall be equal to 100% of the principal amount thereof
plus accrued and unpaid interest, including Additional Interest, if any, to the
date fixed for redemption.

     Section 2.8  Exchange.   At any time, the Company may terminate ONEOK
                  --------
Capital Trust I and cause the Debt Securities to be distributed to Holders of
the Trust Securities of ONEOK Capital Trust I in liquidation of ONEOK Capital
Trust I.

     Section 2.9  Denomination.  The Debt Securities shall be in registered
                  ------------
form without coupons and shall be issuable in denominations of [$25] and
integral multiples thereof.

     Section 2.10 Currency.   Principal and interest and other amounts payable
                  --------
on the Debt Securities shall be payable in Dollars.

     Section 2.11 Form of Debt Securities.   The Debt Securities shall be
                  -----------------------
substantially in the form attached as Exhibit A hereto.
                                      ---------

     Section 2.12 Securities Registrar and Paying Agent.  The Trustee shall
                  -------------------------------------
initially serve as Securities Registrar and Paying Agent.

     Section 2.13 Sinking Fund Obligations.  The Company has no obligation to
                  ------------------------
redeem or purchase any Debt Securities pursuant to any sinking fund or analogous
requirement or upon the happening of a specified event or at the option of a
Holder thereof.

                                   ARTICLE 3

                           Miscellaneous Provisions

     Section 3.1  The Indenture, as supplemented and amended by this
Supplemental Indenture No. 1, is in all respects hereby adopted, ratified and
confirmed.

     Section 3.2  This Supplemental Indenture No. 1 may be executed in any
number of counterparts, each of which shall be an original, but such
counterparts shall together constitute but one and the same instrument.

                                       4
<PAGE>

     Section 3.3  THIS SUPPLEMENTAL INDENTURE NO. 1 AND EACH SECURITY SHALL
BE DEEMED TO BE A CONTRACT MADE UNDER THE LAWS OF THE STATE OF NEW YORK AND
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
NEW YORK WITHOUT REGARD TO CONFLICTS OF LAWS PRINCIPLES THEREOF.

     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture No. 1 to be duly executed, as of the day and year first written above.

                              ONEOK, Inc.


                              By:________________________________
                              Its:

Attest:___________________
       Secretary
                              Executed in ___________________.



                              ___________________, as Trustee


                              By:________________________________
                              Name:
                              Title:

                              Executed in ____________________.

                                       5
<PAGE>

                                   EXHIBIT A

                          [FORM OF FACE OF SECURITY]

     [IF THE SECURITY IS TO BE A GLOBAL SECURITY - This Security is a Global
Security within the meaning of the Indenture hereinafter referred to and is
registered in the name of The Depository Trust Company (the "Depository") or a
nominee of the Depository.  This Security is exchangeable for Securities
registered in the name of a person other than the Depository or its nominee only
in the limited circumstances described in the Indenture and may not be
transferred except as a whole by the Depository to a nominee of the Depository
or by a nominee of the Depository to the Depository or another nominee of the
Depository.]


                                  ONEOK, INC.
                 ____% Junior Subordinated Debentures due 20__

No. ___________                $_____________                 CUSIP____________


     ONEOK, Inc., a corporation organized and existing under the laws of
Oklahoma (the "Company," which term includes any successor corporation under the
Indenture hereinafter referred to), for value received, hereby promises to pay
to _______________, or registered assigns, the principal sum of_________________
Dollars on _____________, 20__.  The Company further promises to pay interest on
said principal sum from _______________, 1999 or from the most recent interest
payment date (each such date, an "Interest Payment Date") on which interest has
been paid or duly provided for, quarterly (subject to deferral as set forth
herein) in arrears on ____________, ____________, ____________ and ____________
of each year, commencing ____________, 1999, at the rate of ____% per annum,
until the principal hereof shall have become due and payable, plus Additional
Interest, if any, until the principal hereof is paid or duly provided for or
made available for payment and on any overdue principal and (without duplication
and to the extent that payment of such interest is enforceable under applicable
law) on any overdue installment of interest at the rate of ____% per annum,
compounded quarterly.  The amount of interest payable for any period will be
computed on the basis of twelve 30-day months and a 360-day year.  The amount of
interest payable for any partial period shall be computed on the basis of the
actual number of elapsed days based on a 360-day year of twelve 30-day months.
In the event that any date on which interest is payable on this Security is not
a Business Day, then a payment of the interest payable on such date will be made
on the next succeeding day which is a Business Day (and without any interest or
other payment in respect of any such delay), except that, if such Business Day
is in the next succeeding calendar year, such payment shall be made on the
immediately preceding Business Day, in each case with the same force and effect
as if made on the date the payment was originally payable.  A "Business Day"
shall mean any day other than (i) a Saturday or Sunday, (ii) a day on which
banking institutions in The City of New York are authorized or required by law
or executive order to remain closed or (iii) a day on which the Corporate Trust
Office of the Trustee or the principal office of the Property Trustee under the
Trust Agreement hereinafter referred to for ONEOK Capital Trust I, is closed for
business.  The interest installment so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the Person in whose name

                                      A-1
<PAGE>

this Security (or one or more Predecessor Securities, as defined in the
Indenture) is registered at the close of business on the Regular Record Date for
such interest installment, which shall be (i) in the case of Securities of this
series represented by one or more Global Securities, the Business Day next
preceding such Interest Payment Date and (ii) in the case of Securities not
represented by one or more Global Securities, the date which is fifteen days
next preceding such Interest Payment Date (whether or not a Business Day). Any
such interest installment not so punctually paid or duly provided for shall
forthwith cease to be payable to the Holder on such Regular Record Date and may
either be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on a Special
Record Date for the payment of such Defaulted Interest to be fixed by the
Trustee, notice whereof shall be given to Holders of Securities of this series
not less than 10 days prior to such Special Record Date, or be paid at any time
in any other lawful manner not inconsistent with the requirements of any
securities exchange on which the Securities of this series may be listed or
traded, and upon such notice as may be required by such exchange, all as more
fully provided in said Indenture.

     So long as no Event of Default under the Indenture shall have occurred and
be continuing, the Company shall have the right at any time during the term of
this Security to defer the payment of interest on such Security, at any time or
from time to time for up to [20] consecutive quarterly interest payment periods
with respect to each deferral period (each an "Extension Period"), during which
Extension Periods the Company shall have the right to make payments of interest
on any Interest Payment Date, and at the end of which the Company shall pay all
interest then accrued and unpaid (together with Additional Interest thereon to
the extent permitted by applicable law); provided, however, that no Extension
Period shall extend beyond the Maturity of the principal of this Security;
provided further, that during any Extension Period, the Company shall not (i)
declare or pay any dividends or distributions on, or redeem, purchase, acquire
or make a liquidation payment with respect to, any of its capital stock or (ii)
make any payment of principal of, or interest or premium, if any, on, or repay,
repurchase or redeem any debt security issued by it that ranks pari passu with
or junior in interest to this Security or make any guarantee payments with
respect to any guarantee by the Company of the debt securities of any of its
Subsidiaries if such guarantee ranks pari passu with or junior in interest to
this Security (other than (a) dividends or distributions in Common Stock, (b)
any declaration of a dividend in connection with the implementation of a Rights
Plan, the issuance of any Common Stock or any class or series of preferred stock
of the Company under any Rights Plan or the repurchase of any rights distributed
pursuant to a Rights Plan, and (c) purchases of Common Stock related to the
issuance of Common Stock under any of the Company's benefit plans for their
respective directors, officers or employees).  Prior to the termination of any
such Extension Period, the Company may further extend the interest payment
period; provided that no Extension Period shall exceed [20] consecutive quarters
or extend beyond the Maturity of this Security.  Upon the termination of any
such Extension Period and upon the payment of all accrued and unpaid interest
and any Additional Interest then due, the Company may elect to begin a new
Extension Period, subject to the requirements hereof.  No interest shall be due
and payable during an Extension Period except at the end thereof.  The Company
shall give the Holder of this Security and the Trustee written notice of its
election to begin any Extension Period at least one Business Day prior to the
earlier of (i) the next succeeding date on which Distributions on the Preferred
Securities of ONEOK Capital Trust I would be payable but for such deferral or
(ii) the date the Administrative Trustee is required to give notice to any
securities exchange or other applicable self-regulatory organization or to
holders

                                      A-2
<PAGE>

of such Preferred Securities of the record date or the date such Distributions
are payable, but in any event not less than one Business Day prior to such
record date.

     Payment of the principal of and interest on this Security will be made at
the office or agency of the Company maintained for that purpose in the United
States, in such coin or currency of the United States of America as at the time
of payment is legal tender for payment of public and private debts; provided,
however, that at the option of the Company payment of interest may be made (i)
by check mailed to the address of the Person entitled thereto as such address
shall appear in the Securities Register or (ii) by wire transfer in immediately
available funds at such place and to such account as may be designated by the
Person entitled thereto as specified in the Securities Register.

     The indebtedness evidenced by this Security is, to the extent provided in
the Indenture, subordinate and subject in right of payments to the prior payment
in full of all Senior Debt of the Company, and this Security is issued subject
to the provisions of the Indenture with respect thereto. Each Holder of this
Security, by accepting the same, (a) agrees to and shall be bound by such
provisions, (b) authorizes and directs the Trustee on his behalf to take such
actions as may be necessary or appropriate to effectuate the subordination so
provided and (c) appoints the Trustee his attorney-in-fact for any and all such
purposes.  Each Holder hereof, by his acceptance hereof, waives all notice of
the acceptance of the subordination provisions contained herein and in the
Indenture by each holder of Senior Debt of the Company, whether now outstanding
or hereafter incurred, and waives reliance by each such holder upon said
provisions.

     Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been executed by the
Trustee referred to on the reverse hereof by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

                                      A-3
<PAGE>

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal.

Dated:
                                             ONEOK, Inc.


                                             By:_______________________________
                                                [President or Vice President]
Attest:

_____________________________________
[Secretary or Assistant Secretary]

  SWORN TO ME and subscribed in my presence in the City of _______________,
State of _______________ this ____ day of _______________, 1999.


                                             __________________________________
                                             Notary Public


                                             Commission Expires:_______________

                                             [NOTARIAL SEAL]


  This is one of the Securities referred to in the within-mentioned Indenture.


Dated:
                                             ______________________, as Trustee


                                             By:_______________________________
                                                      Authorized Officer

                                      A-4
<PAGE>

                         [FORM OF REVERSE OF SECURITY]

  This Security is one of a duly authorized issue of securities of the Company
(the "Securities"), issued and to be issued in one or more series under the
Junior Subordinated Indenture dated as of ________________, 1999, as
supplemented and amended (the "Indenture"), between the Company and
___________________, as Trustee (the "Trustee," which term includes any
successor trustee under the Indenture), to which Indenture and all indentures
supplemental thereto (including, without limitation, Supplemental Indenture No.
1 thereto) reference is hereby made for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Trustee, the
Company and the Holders of the Securities, and of the terms upon which the
Securities are, and are to be, authenticated and delivered.  This Security is
one of the series designated on the face hereof, limited in aggregate principal
amount to $____________.

  All terms used in this Security that are defined in the Indenture or in the
Amended and Restated Trust Agreement dated as of ______________, 1999 (the
"Trust Agreement"), for ONEOK Capital Trust I among the Company, as Depositor,
and the [Trustee] and the other trustees named therein, shall have the meanings
assigned to them in the Indenture or the Trust Agreement, as the case may be.

  The Company may at any time, at its option, on or after _____________, 20__,
and subject to the terms and conditions of Article XI of the Indenture, redeem
this Security in whole at any time or in part from time to time, without premium
or penalty, at a redemption price equal to 100% of the principal amount thereof
plus the accrued and unpaid interest, including Additional Interest, if any, to
the Redemption Date.

  Upon the occurrence and continuance of a Special Event in respect of ONEOK
Capital Trust I, the Company may, at its option, at any time within 90 days of
the occurrence of such Special Event, redeem this Security, in whole but not in
part, subject to the provisions of Section 11.7 and the other provisions of
Article XI of the Indenture, at a redemption price equal to 100% of the
principal amount thereof plus accrued and unpaid interest, including Additional
Interest, if any, to the Redemption Date.

  In the event of redemption of this Security in part only, a new Security or
Securities of this series for the unredeemed portion hereof will be issued in
the name of the Holder hereof upon the cancellation hereof.

  The Indenture contains provisions for satisfaction, discharge and defeasance
at any time of the entire indebtedness of this Security upon compliance by the
Company with certain conditions set forth in the Indenture.

  The Indenture permits, with certain exceptions as therein provided, the
Company and the Trustee at any time to enter into a supplemental indenture or
indentures for the purpose of modifying in any manner the rights and obligations
of the Company and of the Holders of the Securities, with the consent of the
Holders of a majority in principal amount of the Outstanding Securities of each
series to be affected by such supplemental indenture.  The Indenture also
contains provisions permitting Holders of specified percentages in principal
amount of the Securities of each series at the time

                                      A-5
<PAGE>

Outstanding, on behalf of the Holders of all Securities of such series, to waive
compliance by the Company with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Security shall be conclusive and binding upon such
Holder and upon all future Holders of this Security and of any Security issued
upon the registration of transfer hereof or in exchange herefor or in lieu
hereof, whether or not notation of such consent or waiver is made upon this
Security.

  As provided in and subject to the provisions of the Indenture, if an Event of
Default with respect to Securities of this series at the time Outstanding occurs
and is continuing, then and in every such case the Trustee or the Holders of not
less than 25% in principal amount of the Outstanding Securities of this series
may declare the principal amount of all the Securities of this series to be due
and payable immediately, by a notice in writing to the Company (and to the
Trustee if given by Holders), provided that, if upon an Event of Default, the
Trustee or the Holders of not less than 25% in principal amount of the
Outstanding Securities of this series fail to declare the principal of all the
Securities of this series to be immediately due and payable, the holders of at
least 25% in aggregate Liquidation Amount of the Preferred Securities of ONEOK
Capital Trust I then outstanding shall have such right by a notice in writing to
the Company and the Trustee; and upon any such declaration the principal amount
of and the accrued interest (including any Additional Interest) on all the
Securities of this series shall become immediately due and payable, provided
that the payment of principal and interest (including any Additional Interest)
on such Securities shall remain subordinated to the extent provided in Article
XIII of the Indenture.

  No reference herein to the Indenture and no provision of this Security or of
the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal and interest on this Security
at the times, place and rate, and in the coin or currency, herein prescribed.

  As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Security is registrable in the Securities Register,
upon surrender of this Security for registration of transfer at the office or
agency of the Company maintained under Section 10.2 of the Indenture duly
endorsed by, or accompanied by a written instrument of transfer in form
satisfactory to the Company and the Securities Registrar duly executed by, the
Holder hereof or his attorney duly authorized in writing, and thereupon one or
more new Securities of this series, of authorized denominations and for the same
aggregate principal amount, will be issued to the designated transferee or
transferees.  No service charge shall be made for any such registration of
transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith.

  Prior to due presentment of this Security for registration of transfer, the
Company and the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not this Security be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

  The Securities of this series are issuable only in registered form without
coupons in denominations of [$25] and any integral multiple thereof.  As
provided in the Indenture and subject to certain limitations therein set forth,
Securities of this series are exchangeable for a like aggregate principal

                                      A-6
<PAGE>

amount of Securities of such series of a different authorized denomination, as
requested by the Holder surrendering the same.

  The Company and, by its acceptance of this Security or a beneficial interest
therein, the Holder of, and any Person that acquires a beneficial interest in,
this Security agree that for United States federal, state and local tax purposes
it is intended that this Security constitute indebtedness.

  THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO CONFLICTS OF
LAWS PRINCIPLES THEREOF.

                                      A-7

<PAGE>

                                                                  Exhibit 4.3(a)

                            CERTIFICATE OF TRUST OF
                             ONEOK CAPITAL TRUST I

                  THIS Certificate of Trust of ONEOK CAPITAL TRUST I (the
"Trust") is being duly executed and filed on behalf of the Trust by the
undersigned, as trustees, to form a business trust under the Delaware Business
Trust Act (12 Del. C. (S) 3801 et seq.) (the "Act").
              ------           -- ---

                  1.  Name. The name of the business trust formed hereby is
                      ----
ONEOK CAPITAL TRUST I.


                  2.  Delaware Trustee. The name and business address of the
                      ----------------
trustee of the Trust in the State of Delaware is


                  3.  Effective Date. This Certificate of Trust shall be
                      --------------
effective upon filing with the Secretary of State.


                  IN WITNESS WHEREOF, the undersigned have duly executed this
Certificate of Trust in accordance with Section 3811(a)(1) of the Act.


                                                                              ,
                                                      as
                                                      trustee


                                                      By:______________________


                                                                              ,
                                                      as trustee


                                                      By:______________________

<PAGE>

                                                                  Exhibit 4.3(b)

                             CERTIFICATE OF TRUST OF
                             ONEOK CAPITAL TRUST II

                  THIS Certificate of Trust of ONEOK CAPITAL TRUST II (the
"Trust") is being duly executed and filed on behalf of the Trust by the
undersigned, as trustees, to form a business trust under the Delaware Business
Trust Act (12 Del. C. (S) 3801 et seq.) (the "Act").
              ------           -- ---

                  1.   Name. The name of the business trust formed hereby is
                       ----
ONEOK CAPITAL TRUST II.


                  2.   Delaware Trustee. The name and business address of the
                       ----------------
trustee of the Trust in the State of Delaware is.


                  3.   Effective Date. This Certificate of Trust shall be
                       --------------
effective upon filing with the Secretary of State.


                  IN WITNESS WHEREOF, the undersigned have duly executed this
Certificate of Trust in accordance with Section 3811(a)(1) of the Act.




                                                                            ,as
                                                    trustee


                                                    By:________________________



                                                                            ,as
                                                    trustee


                                                    By:________________________

<PAGE>

                                                                 EXHIBIT 4.4(A)

                                TRUST AGREEMENT
                                ---------------

     This TRUST AGREEMENT, dated as of ________, 1999 (this "Trust
Agreement"), among (i) ONEOK, INC., an Oklahoma corporation (the "Depositor"),
(ii),               , a Delaware corporation (the "Delaware Trustee"), and
(iii)                            , a national banking association (the
"Property Trustee") (collectively with the Delaware Trustee, the "Trustees").
The Depositor and the Trustees hereby agree as follows:

     1.   The trust created hereby (the "Trust") shall be known as "ONEOK
CAPITAL TRUST I" in which name the Trustees, or the Depositor to the extent
provided herein, may engage in the transactions contemplated hereby, make and
execute contracts, and sue and be sued.

     2.   The Depositor hereby assigns, transfers, conveys and sets over to
the Trust the sum of $10. The Trustees hereby acknowledge receipt of such amount
from the Depositor, which amount shall constitute the initial trust estate. The
Trustees hereby declare that they will hold the trust estate for the Depositor.
It is the intention of the parties hereto that the Trust created hereby
constitutes a business trust under Chapter 38 of Title 12 of the Delaware Code,
12 Del. C. (S) 3801, et seq. (the "Business Trust Act"), and that this document
   ------            ------
constitutes the governing instrument of the Trust. The Trustees are hereby
authorized and directed to execute and file a certificate of trust with the
Delaware Secretary of State in accordance with the provisions of the Business
Trust Act.

     3.   The Depositor, the Trustees and certain other trustees to be
hereafter appointed will enter into an amended and restated Trust Agreement,
satisfactory to each such party and substantially in the form included as an
exhibit to the 1933 Act Registration Statement (as defined below), to provide
for the contemplated operation of the Trust created hereby and the issuance of
the Preferred Securities and Common Securities referred to therein. Prior to the
execution and delivery of such amended and restated Trust Agreement, the
Trustees shall not have any duty or obligation hereunder or with respect to the
trust estate, except as otherwise required by applicable law or as may be
necessary to obtain prior to such execution and delivery any licenses, consents
or approvals required by applicable law or otherwise.

     4.   The Depositor and the Trustees hereby authorize and direct the
Depositor, as the Depositor of the Trust, (i) to file with the Securities and
Exchange Commission (the "Commission") and execute, in each case on behalf of
the Trust, (a) the Registration Statement on Form S-3 (the "1933 Act
Registration Statement"), including any pre-effective or post-effective
amendments to the 1933 Act Registration Statement, relating to the registration
under the Securities Act of 1933, as amended (the "1933 Act"), of the Preferred
Securities of the Trust and certain other securities, (b) any Prospectus or
Preliminary Prospectus relating to the Preferred Securities required to be filed
under the 1933 Act, and (c) a Registration Statement on Form 8-A (the "1934 Act
Registration Statement") (including all pre-effective and post-effective
amendments thereto) relating to the registration of the Preferred Securities of
the Trust under the Securities Exchange Act of 1934, as amended; (ii) to file
with the New York Stock Exchange or any other national stock exchange or The
Nasdaq National Market (each, an "Exchange") and execute on behalf of the Trust
one or more listing applications and all other applications, statements,
certificates, agreements and other instruments as shall be necessary or
desirable to cause the Preferred Securities to be listed on any of the
Exchanges; (iii) to file and execute on behalf of the Trust such applications,
reports, surety bonds, irrevocable consents, appointments of attorney for
service of process and other papers and documents as shall
<PAGE>

be necessary or desirable to register the Preferred Securities under the
securities or blue sky laws of such jurisdictions as the Depositor, on behalf of
the Trust, may deem necessary or desirable and (iv) to execute on behalf of the
Trust that certain Underwriting Agreement relating to the Preferred Securities,
among the Trust, the Depositor, and the several Underwriters named therein,
substantially in the form included as an exhibit to the 1933 Act Registration
Statement. In connection with the filings referred to above, the Depositor
hereby constitutes and appoints
                                                          as its true and lawful
attorneys-in-fact and agents, with full power of substitution and
resubstitution, for the Depositor or in the Depositor's name, place and stead,
in its capacity as Depositor of the Trust, to sign any and all amendments
(including post-effective amendments) to the 1933 Act Registration Statement and
the 1934 Act Registration Statement and to file the same, with all exhibits
thereto, and any other documents in connection therewith, with the Commission,
the Exchange and administrators of state securities or blue sky laws, granting
unto said attorneys-in-fact and agents full power and authority to do and
perform each and every act and thing requisite and necessary to be done in
connection therewith, as fully to all intents and purposes as the Depositor
might or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or their respective substitute or
substitutes, shall do or cause to be done by virtue hereof.

     5.   This Trust Agreement may be executed in one or more counterparts.

     6.   The number of Trustees initially shall be two (2) and thereafter the
number of Trustees shall be such number as shall be fixed from time to time by a
written instrument signed by the Depositor which may increase or decrease the
number of Trustees; provided, however, that to the extent required by the
Business Trust Act, one Trustee shall either be a natural person who is a
resident of the State of Delaware or, if not a natural person, an entity which
has its principal place of business in the State of Delaware and otherwise meets
the requirements of applicable Delaware law. Subject to the foregoing, the
Depositor is entitled to appoint or remove without cause any Trustee at any
time. The Trustees may resign upon thirty (30) days' prior notice to the
Depositor.

     7.   This Trust Agreement shall be governed by, and construed in
accordance with, the laws of the State of Delaware (without regard to conflict
of laws principles).

     8.   The Delaware Trustee shall not have any of the powers or duties of
the Trustees set forth herein, except as required under the Business Trust Act.
The Delaware Trustee shall be a Trustee hereunder for the sole and limited
purpose of fulfilling the requirements of ss. 3807(a) of the Business Trust Act.

                           [SIGNATURE PAGE FOLLOWS]

                                       2
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement
to be duly executed as of the day and year first above written.

                                ONEOK, INC., as Depositor

                                By:___________________________________________
                                                                        Signed
                                this   day of   , 1999, in the City of   , the
                                State of

                                                                         , as
                                Trustee

                                By:___________________________________________


                                                                         , as
                                Trustee

                                By:___________________________________________

                                       3

<PAGE>

                                                                  Exhibit 4.4(b)
                                TRUST AGREEMENT
                                ---------------

     This TRUST AGREEMENT, dated as of ________, 1999 (this "Trust Agreement"),
among (i) ONEOK, INC., an Oklahoma corporation (the "Depositor"), (ii)         ,
a Delaware corporation (the "Delaware Trustee"), and (iii)                  , a
national banking association (the "Property Trustee") (collectively with the
Delaware Trustee, the "Trustees"). The Depositor and the Trustees hereby agree
as follows:

     1.   The trust  created  hereby  (the  "Trust")  shall be known as "ONEOK
CAPITAL  TRUST II" in which name the  Trustees,  or the  Depositor to the extent
provided herein, may engage in the transactions  contemplated  hereby,  make and
execute contracts, and sue and be sued.

     2.   The Depositor hereby assigns, transfers, conveys and sets over to the
Trust the sum of $10. The Trustees hereby acknowledge receipt of such amount
from the Depositor, which amount shall constitute the initial trust estate. The
Trustees hereby declare that they will hold the trust estate for the Depositor.
It is the intention of the parties hereto that the Trust created hereby
constitutes a business trust under Chapter 38 of Title 12 of the Delaware Code,
12 Del. C. (S) 3801, et seq. (the "Business Trust Act"), and that this document
   -------           ------
constitutes the governing instrument of the Trust. The Trustees are hereby
authorized and directed to execute and file a certificate of trust with the
Delaware Secretary of State in accordance with the provisions of the Business
Trust Act.

     3.   The Depositor, the Trustees and certain other trustees to be
hereafter appointed will enter into an amended and restated Trust Agreement,
satisfactory to each such party and substantially in the form included as an
exhibit to the 1933 Act Registration Statement (as defined below), to provide
for the contemplated operation of the Trust created hereby and the issuance of
the Preferred Securities and Common Securities referred to therein. Prior to the
execution and delivery of such amended and restated Trust Agreement, the
Trustees shall not have any duty or obligation hereunder or with respect to the
trust estate, except as otherwise required by applicable law or as may be
necessary to obtain prior to such execution and delivery any licenses, consents
or approvals required by applicable law or otherwise.

     4.   The Depositor and the Trustees hereby authorize and direct the
Depositor, as the Depositor of the Trust, (i) to file with the Securities and
Exchange Commission (the "Commission") and execute, in each case on behalf of
the Trust, (a) the Registration Statement on Form S-3 (the "1933 Act
Registration Statement"), including any pre-effective or post-effective
amendments to the 1933 Act Registration Statement, relating to the registration
under the Securities Act of 1933, as amended (the "1933 Act"), of the Preferred
Securities of the Trust and certain other securities, (b) any Prospectus or
Preliminary Prospectus relating to the Preferred Securities required to be filed
under the 1933 Act, and (c) a Registration Statement on Form 8-A (the "1934 Act
Registration Statement") (including all pre-effective and post-effective
amendments thereto) relating to the registration of the Preferred Securities of
the Trust under the Securities Exchange Act of 1934, as amended; (ii) to file
with the New York Stock Exchange or any other national stock exchange or The
Nasdaq National Market (each, an "Exchange") and execute on behalf of the Trust
one or more listing applications and all other applications, statements,
certificates, agreements and other instruments as shall be necessary or
desirable to cause the Preferred Securities to be listed on any of the
Exchanges; (iii) to file and execute on behalf of the Trust such applications,
reports, surety bonds, irrevocable consents, appointments of attorney for
service of process and other papers and documents as shall
<PAGE>

be necessary or desirable to register the Preferred Securities under the
securities or blue sky laws of such jurisdictions as the Depositor, on behalf of
the Trust, may deem necessary or desirable and (iv) to execute on behalf of the
Trust that certain Underwriting Agreement relating to the Preferred Securities,
among the Trust, the Depositor, and the several Underwriters named therein,
substantially in the form included as an exhibit to the 1933 Act Registration
Statement. In connection with the filings referred to above, the Depositor
hereby constitutes and appoints as its true and lawful attorneys-in-fact and
agents, with full power of substitution and resubstitution, for the Depositor or
in the Depositor's name, place and stead, in its capacity as Depositor of the
Trust, to sign any and all amendments (including post-effective amendments) to
the 1933 Act Registration Statement and the 1934 Act Registration Statement and
to file the same, with all exhibits thereto, and any other documents in
connection therewith, with the Commission, the Exchange and administrators of
state securities or blue sky laws, granting unto said attorneys-in-fact and
agents full power and authority to do and perform each and every act and thing
requisite and necessary to be done in connection therewith, as fully to all
intents and purposes as the Depositor might or could do in person, hereby
ratifying and confirming all that said attorneys-in-fact and agents or any of
them, or their respective substitute or substitutes, shall do or cause to be
done by virtue hereof.

     5.   This Trust Agreement may be executed in one or more counterparts.

     6.   The number of Trustees initially shall be two (2) and thereafter the
number of Trustees shall be such number as shall be fixed from time to time by a
written instrument signed by the Depositor which may increase or decrease the
number of Trustees; provided, however, that to the extent required by the
Business Trust Act, one Trustee shall either be a natural person who is a
resident of the State of Delaware or, if not a natural person, an entity which
has its principal place of business in the State of Delaware and otherwise meets
the requirements of applicable Delaware law. Subject to the foregoing, the
Depositor is entitled to appoint or remove without cause any Trustee at any
time. The Trustees may resign upon thirty (30) days' prior notice to the
Depositor.

     7.   This  Trust  Agreement  shall be  governed  by,  and  construed  in
accordance  with, the laws of the State of Delaware  (without regard to conflict
of laws principles).

     8.   The Delaware  Trustee  shall not have any of the powers or duties of
the Trustees set forth herein,  except as required under the Business Trust Act.
The  Delaware  Trustee  shall be a Trustee  hereunder  for the sole and  limited
purpose of fulfilling the requirements of (S) 3807(a) of the Business Trust Act.

                           [SIGNATURE PAGE FOLLOWS]

                                       2
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement to
be duly executed as of the day and year first above written.

                                ONEOK, INC., as Depositor

                                By:_____________________________________________
                                                                          Signed
                                this   day of    , 1999, in the City of    , the
                                State of


                                                                            , as
                                Trustee

                                By:_____________________________________________



                                                                            , as
                                Trustee

                                By:_____________________________________________


                                       3

<PAGE>

                                                                     EXHIBIT 4.5

                              AMENDED AND RESTATED


                                TRUST AGREEMENT


                                     among


                                  ONEOK, INC.
                                 as Depositor,


                          [________________________],
                              as Property Trustee,



                          [________________________],
                              as Delaware Trustee,


                                      and


                          [_________________________],


                          Dated as of [______ __] 1999


                             ONEOK CAPITAL TRUST I
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                              Page
                                                                                                              ----
<S>                                                                                                           <C>
ARTICLE I.    DEFINED TERMS.................................................................................     1
     Section   1.1.   Definitions...........................................................................     1

ARTICLE II.    ESTABLISHMENT OF THE TRUST...................................................................     9
     Section   2.1.   Name..................................................................................     9
     Section   2.2.   Office of the Delaware Trustee; Principal Place of Business...........................    10
     Section   2.3.   Initial Contribution of Trust Property; Organizational Expenses.......................    10
     Section   2.4.   Issuance of the Preferred Securities..................................................    10
     Section   2.5.   Issuance of the Common Securities; Subscription and Purchase of Notes.................    10
     Section   2.6.   Declaration of Trust..................................................................    10
     Section   2.7.   Authorization to Enter into Certain Transactions......................................    11
     Section   2.8.   Assets of Trust.......................................................................    14
     Section   2.9.   Title to Trust Property...............................................................    14

ARTICLE III.  PAYMENT ACCOUNT...............................................................................    14
     Section   3.1.   Payment Account.......................................................................    14

ARTICLE IV.   DISTRIBUTIONS; REDEMPTION.....................................................................    15
      Section  4.1.   Distributions.........................................................................    15
      Section  4.2.   Redemption............................................................................    16
      Section  4.3.   Subordination of Common Securities....................................................    18
      Section  4.4.   Payment Procedures.  18...............................................................    18
      Section  4.5.   Tax Returns and Reports.      18......................................................    18
      Section  4.6.   Payment of Taxes, Duties, Etc.  of the Trust..........................................    19
      Section  4.7.   Payments under Indenture or Pursuant to Direct Actions................................    19

ARTICLE V.    TRUST SECURITIES CERTIFICATES.................................................................    19
     Section   5.1.   Initial Ownership.....................................................................    19
     Section   5.2.   The Trust Securities Certificates.....................................................    19
     Section   5.3.   Execution and Delivery of Trust Securities Certificates...............................    20
     Section   5.4.   Registration of Transfer and Exchange of Preferred Securities Certificates............    20
     Section   5.5.   Mutilated, Destroyed. Lost or Stolen Trust Securities Certificates....................    21
     Section   5.6.   Persons Deemed Securityholders........................................................    21
     Section   5.7.   Access to List of Securityholders' Names and Addresses................................    21
     Section   5.8.   Maintenance of Office or Agency.......................................................    22
     Section   5.9.   Appointment of Paying Agent...........................................................    22
     Section   5.10.  Ownership of Common Securities by Depositor...........................................    22
     Section   5.11.  Book-Entry Preferred Securities Certificates; Common Securities Certificate...........    23
     Section   5.12.  Notices to Clearing Agency............................................................    23
     Section   5.13.  Definitive Preferred Securities Certificates..........................................    24
</TABLE>

                                        i
<PAGE>

<TABLE>
<S>                                                                                                              <C>
     Section 5.14.  Rights of Securityholders..................................................................  24

ARTICLE VI.    ACTS OF SECURITYHOLDERS; MEETINGS; VOTING.......................................................  26
     Section 6.1.   Limitations on Voting Rights...............................................................  26
     Section 6.2.   Notice of Meetings.........................................................................  27
     Section 6.3.   Meetings of Preferred Securityholders......................................................  27
     Section 6.4.   Voting Rights..............................................................................  28
     Section 6.5.   Proxies, etc...............................................................................  28
     Section 6.6.   Securityholder Action by Written Consent...................................................  28
     Section 6.7.   Record Date for Voting and Other Purposes..................................................  28
     Section 6.8.   Acts of Securityholders....................................................................  29
     Section 6.9.   Inspection of Records......................................................................  30

ARTICLE VII.   REPRESENTATIONS AND WARRANTIES..................................................................  30
     Section 7.1.   Representations and Warranties of the Property Trustee and the Delaware Trustee............  30
     Section 7.2.   Representations and Warranties of Depositor................................................  31

ARTICLE VIII.  THE TRUSTEES....................................................................................  31
     Section 8.1.   Certain Duties and Responsibilities........................................................  31
     Section 8.2.   Certain Notices............................................................................  33
     Section 8.3.   Certain Rights of Property Trustee.........................................................  33
     Section 8.4.   Not Responsible for Recitals or Issuance of Securities.....................................  35
     Section 8.5.   May Hold Securities........................................................................  35
     Section 8.6.   Compensation; Indemnity; Fees..............................................................  35
     Section 8.7.   Corporate Property Trustee Required; Eligibility of Trustees...............................  36
     Section 8.8.   Conflicting Interests......................................................................  37
     Section 8.9.   Co-Trustees and Separate Trustee...........................................................  37
     Section 8.10.  Resignation and Removal; Appointment of Successor..........................................  38
     Section 8.11.  Acceptance of Appointment by Successor.....................................................  40
     Section 8.12.  Merger, Conversion, Consolidation or Succession to Business................................  40
     Section 8.13.  Preferential Collection of Claims Against Depositor or Trust...............................  41
     Section 8.14.  Reports by Property Trustee................................................................  41
     Section 8.15.  Reports to the Property Trustee............................................................  42
     Section 8.16.  Evidence of Compliance with Conditions Precedent...........................................  42
     Section 8.17.  Number of Trustees.........................................................................  42
     Section 8.18.  Delegation of Power........................................................................  43

ARTICLE IX.    TERMINATION, LIQUIDATION AND MERGER ............................................................  43
     Section 9.1.   Termination Upon Expiration Date...........................................................  43
     Section 9.4.   Liquidation................................................................................  44
     Section 9.5.   Mergers, Consolidations, Amalgamations or Replacements of the Trust........................  45

ARTICLE X.     MISCELLANEOUS PROVISIONS........................................................................  46
     Section 10.1.  Limitation of Rights of Securityholders....................................................  46
     Section 10.2.  Amendment..................................................................................  46
</TABLE>

                                      ii
<PAGE>

<TABLE>
          <S>                                                                                         <C>
          Section 10.3.  Separability..............................................................    47
          Section 10.4.  Governing Law.............................................................    48
          Section 10.5.  Payments Due on Non-Business Day..........................................    48
          Section 10.6.  Successors................................................................    48
          Section 10.7.  Headings..................................................................    48
          Section 10.8.  Reports, Notices and Demands..............................................    48
          Section 10.9.  Agreement Not to Petition.................................................    49
          Section 10.10. Trust Indenture Act; Conflict with Trust Indenture Act....................    49
          Section 10.11. Acceptance of Terms of Trust Agreement, Guarantee and Indenture...........    50
</TABLE>

                                      iii
<PAGE>

                             ONEOK CAPITAL TRUST I

             Certain Sections of this Trust Agreement relating to
                        Sections 310 through 318 of the
                         Trust Indenture Act of 1939:

<TABLE>
<CAPTION>
Trust Indenture                                                                                                Trust Agreement
Act Section                                                                                                         Section
- ---------------                                                                                                ---------------
<S>                                                                                                        <C>
(S) 310(a)(1) ..........................................................................................               8.7
       (a)(2) ..........................................................................................               8.7
       (a)(3) ..........................................................................................               8.9
       (a)(4) ..........................................................................................        2.7(a)(ii)
       (b) .............................................................................................               8.8
(S) 311(a) .............................................................................................              8.13
       (b) .............................................................................................            8.13
(S) 312(a) .............................................................................................               5.7
       (b) .............................................................................................               5.7
       (c) .............................................................................................               5.7
(S) 313(a) .............................................................................................          8.14(a)
       (a)(4) ..........................................................................................           8.14(b)
       (b) .............................................................................................           8.14(b)
       (c) .............................................................................................              10.8
       (d) .............................................................................................           8.14(c)
(S) 314(a) .............................................................................................              8.15
       (b) .............................................................................................    Not Applicable
       (c)(1) ..........................................................................................              8.16
       (c)(2) ..........................................................................................              8.16
       (c)(3) ..........................................................................................        Applicable
       (d) .............................................................................................        Applicable
       (e) .............................................................................................         1.1, 8.16
(S) 315(a) .............................................................................................   8.1 (a), 8.3(a)
       (b) .............................................................................................         8.2, 10.8
       (c) .............................................................................................            8.1(a)
       (d) .............................................................................................          8.1,.8.3
       (e) .............................................................................................    Not Applicable
(S) 316(a) .............................................................................................    Not Applicable
       (a)(1)(A) .......................................................................................    Not Applicable
       (a)(1)(B) .......................................................................................    Not Applicable
       (a)(2) ..........................................................................................    Not Applicable
       (b) .............................................................................................              5.14
       (c) .............................................................................................               6.7
(S) 317(a)(1) ..........................................................................................    Not Applicable
       (a)(2) ..........................................................................................    Not Applicable
       (b) .............................................................................................               5.9
(S) 318(a) .............................................................................................             10.10
</TABLE>

Note:  This reconciliation and tie sheet shall not, for any purpose, be deemed
to be a part of the Trust Agreement.

                                      iv
<PAGE>

     AMENDED AND RESTATED TRUST AGREEMENT, dated as of [______  __], 1999, among
(i) ONEOK, INC., an Oklahoma corporation (including any successors or assigns,
the "Depositor"), (ii) [____________________], a national banking association
duly organized and existing under the laws of the United States, as property
trustee, (in such capacity, the "Property Trustee" and, in its separate
corporate capacity and not in its capacity as Property Trustee, the "Bank"),
(iii) [_________________], a Delaware corporation, as Delaware trustee (the
"Delaware Trustee"), (iv) [_________________], an [__________] corporation,
whose address is [_____________________________] (the "Administrative Trustee")
(the Property Trustee, the Delaware Trustee and the Administrative Trustee(s)
referred to collectively as the "Trustees") and (v) the several Holders, as
hereinafter defined.

                                  Witnesseth

     Whereas, the Depositor, the Property Trustee and the Delaware Trustee have
heretofore duly declared and established a business trust pursuant to the
Delaware Business Trust Act by entering into that certain Trust Agreement dated
as of [_______ __], 1999 (the "Original Trust Agreement") and by execution and
filing with the Secretary of State of the State of Delaware of the Certificate
of Trust, filed on [________ __],1999, attached hereto as Exhibit A; and

     Whereas, the Depositor and the Trustees desire to amend and restate the
Original Trust Agreement in its entirety as set forth herein to provide for,
among other things, (i) the issuance of the Common Securities by the Trust to
the Depositor, (ii) the issuance and sale of the Preferred Securities by the
Trust pursuant to the Underwriting Agreement, (iii) the acquisition by the Trust
from the Depositor of all of the right, title and interest in the Notes and (iv)
the appointment of the Administrative Trustee(s);

     Now Therefore, in consideration of the agreements and obligations set forth
herein and for other good and valuable consideration, the sufficiency of which
is hereby acknowledged, each party, for the benefit of the other parties and for
the benefit of the Securityholders, hereby amends and restates the Original
Trust Agreement in its entirety and agrees as follows:


                                  ARTICLE I.

                                 Defined Terms

     Section 1.1  Definitions.

     For  all purposes of this Trust Agreement, except as otherwise expressly
provided or unless the context otherwise requires:

     (a)  the terms defined in this Article have the meanings assigned to them
in this Article and include the plural as well as the singular;

     (b)  all other terms used herein that are defined in the Trust Indenture
Act, either directly or by reference therein, have the meanings assigned to them
therein;

                                       1
<PAGE>

     (c)  unless the context otherwise requires, any reference to an "Article"
or a "Section" refers to an Article or a Section, as the case may be, of this
Trust Agreement; and

     (d)  the words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Trust Agreement as a whole and not to any
particular Article, Section or other subdivision.

     "Act" has the meaning specified in Section 6.8.

     "Additional Amount" means, with respect to Trust Securities of a given
Liquidation Amount and/or a given period, the amount of Additional Interest (as
defined in the Indenture) paid by the Depositor on a Like Amount of Notes for
such period.

     "Additional Sums" has the meaning specified in Section 10.6 of the
Indenture.

     "Administrative Trustee(s)" means each of the Persons identified as an
"Administrative Trustee" in the preamble to this Trustee Agreement solely in
such Persons capacity as an Administrative Trustee of the Trust formed and
continued hereunder and not in such Person's individual capacity, or such
Administrative Trustee's successor in interest in such capacity, or any
successor trustee appointed as herein provided.

     "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by, or under direct or indirect common
control with, such specified Person.  For the purposes of this definition,
"control" when used with respect to any specified Person means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise.
The terms "controlling" and "controlled" have meanings correlative to the
foregoing.

     "Bank" has the meaning specified in the preamble to this Trust Agreement.

     "Bankruptcy Event" means, with respect to any Person:

     (a)  the entry of a decree or order by a court having jurisdiction in the
premises judging such Person a bankrupt or insolvent, or approving as properly
filed a petition seeking reorganization, arrangement, adjudication or
composition of or in respect of such Person under any applicable federal or
state bankruptcy, insolvency, reorganization or other similar law, or appointing
a receiver, liquidator, assignee, trustee, sequestrator (or other similar
official) of such Person or of any substantial part of its property or ordering
the winding up or liquidation of its affairs, and the continuance of any such
decree or order unstayed and in effect for a period of 60 consecutive days; or

     (b)  the institution by such Person of proceedings to be adjudicated a
bankrupt or insolvent, or the consent by it to the institution of bankruptcy or
insolvency proceedings against it, or the filing by it of a petition or answer
or consent seeking reorganization or relief under any applicable Federal or
State bankruptcy, insolvency, reorganization or other similar law, or the
consent by it to the filing of any such petition or to the appointment of a
receiver, liquidator, assignee, trustee, sequestrator (or similar official) of
such Person or of any substantial part of its property, or the

                                       2
<PAGE>

making by it of an assignment for the benefit of creditors, or the admission by
it in writing of its inability to pay its debts generally as they become due and
its willingness to be adjudicated a bankrupt, or the taking of corporate action
by such Person in furtherance of any such action.

     "Bankruptcy Laws" has the meaning specified in Section 10.9.

     "Board Resolution" means a copy of a resolution certified by the Secretary
or an Assistant Secretary of the Depositor to have been duly adopted by the
Depositor's Board of Directors, or such committee of the Board of Directors or
officers of the Depositor to which authority to act on behalf of the Board of
Directors has been delegated, and to be in full force and effect on the date of
such certification, and delivered to the Trustees.

     "Book-Entry Preferred Securities Certificate" means a beneficial interest
in the Preferred Securities Certificates, ownership and transfers of which shall
be made through book entries by a Clearing Agency as described in Section 5.11.

     "Business Day" means a day other than (a) a Saturday or Sunday, (b) a day
on which banking institutions in The City of New York are authorized or required
by law or executive order to remain closed or (c) a day on which the Property
Trustee's Corporate Trust Office or the Corporate Trust Office of the Indenture
Trustee is closed for business.

     "Certificate Depository Agreement" means the agreement among the Trust, the
Depositor and The Depository Trust Company, as the initial Clearing Agency,
dated as of the Closing Date, relating to the Trust Securities Certificates,
substantially in the form attached as Exhibit B, as the same may be amended and
supplemented from time to time.

     "Clearing Agency" means an organization registered as a "clearing agency"
pursuant to Section 17A of the Securities Exchange Act of 1934, as amended.  The
Depository Trust Company will be the initial Clearing Agency.

     "Clearing Agency Participant" means a broker, dealer, bank, other financial
institution or other Person for whom from time to time a Clearing Agency effects
book-entry transfers and pledges of securities deposited with the Clearing
Agency.

     "Closing Date" has the meaning specified in the Underwriting Agreement,
which date is also the date of execution and delivery of this Trust Agreement.

     "Code" means the Internal Revenue Code of 1986, as amended.

     "Commission" means the Securities and Exchange Commission, as from time to
time constituted, created under the Securities Exchange Act of 1934, as amended,
or, if at any time after the execution of this instrument such Commission is not
existing and performing the duties now assigned to it under the Trust Indenture
Act, then the body performing such duties at such time.

                                       3
<PAGE>

     "Common Security" means an undivided beneficial interest in the assets of
the Trust, having a Liquidation Amount of $25 and having the rights provided
therefor in this Trust Agreement, including the right to receive Distributions
and a Liquidation Distribution as provided herein.

     "Common Securities Certificate" means a certificate evidencing ownership of
Common Securities, substantially in the form attached as Exhibit C.

     "Corporate Trust Office" means (i) when used with respect to the Property
Trustee, the principal office of the Property Trustee located in [____________],
and (ii) when used with respect to the Indenture Trustee, the principal office
of the Indenture Trustee located in [____________].

     "Definitive Preferred Securities Certificates" means either or both (as the
context requires) of (1) Preferred Securities Certificates issued as (a) Book-
Entry Preferred Securities Certificate or Certificates as provided in Section
5.11(a) and (2) Preferred Securities Certificates issued in certificated, fully
registered form as provided in Section 5.13.

     "Delaware Business Trust Act" means Chapter 38 of Title 12 of the Delaware
Code, 12 Del. C. ((S) ) 3801, et seq., as it may be amended from time to time.

     "Delaware Trustee" means the Person identified as the "Delaware Trustee" in
the preamble to this Trust Agreement solely in its capacity as Delaware Trustee
of the Trust formed and continued hereunder and not in its individual capacity,
or its successor in interest in such capacity, or any successor trustee
appointed as herein provided.

     "Depositor" has the meaning specified in the preamble to this Trust
Agreement.

     "Distribution Date" has the meaning specified in Section 4.1(a).

     "Distributions" means amounts payable in respect of the Trust Securities as
provided in Section 4.1.

     "Early Termination Event" has the meaning specified in Section 9.2.

     "Event of Default" means any one of the following events (whatever the
reason for such Event of Default and whether it shall be voluntary or
involuntary or be effected by operation of law or pursuant to any judgment,
decree or order of any court or any order, rule or regulation of any
administrative or governmental body):

     (a)  the occurrence of an Indenture Event of Default; or

     (b)  default by the Trust in the payment of any Distribution when it
becomes due and payable, and continuation of such default for a period of 30
days; or

     (c)  default by the Trust in the payment of any Redemption Price of any
Trust Security when it becomes due and payable; or

                                       4
<PAGE>

     (d)  default in the performance, or breach, in each case, in any material
respect, of any covenant or warranty of the Trustees in this Trust Agreement
(other than a covenant or warranty a default in the performance or breach of
which is dealt with in clause (b) or (c) above) and continuation of such default
or breach for a period of 90 days after there has been given, by registered or
certified mail, to each defaulting Trustee by the Holders of at least 25% in
aggregate liquidation preference of the Outstanding Preferred Securities a
written notice specifying such default or breach and requiring it to be remedied
and stating that such notice is a "Notice of Default" hereunder; or

     (e)  the occurrence of a Bankruptcy Event with respect to the Property
Trustee and the failure by the Depositor to appoint a successor Property Trustee
within 60 days thereof.

     "Expense Agreement" means the Agreement as to Expenses and Liabilities
between the Depositor and the Trust, substantially in the form attached as
Exhibit D, as amended from time to time.

     "Expiration Date" has the meaning specified in Section 9.1.

     "Guarantee" means the Guarantee Agreement executed and delivered by the
Depositor and [____________], as trustee thereunder, contemporaneously with the
execution and delivery of this Trust Agreement, for the benefit of the holders
of the Preferred Securities, as amended from time to time.

     "Indenture" means the Junior Subordinated Indenture dated as of [_______
__], 1999 between the Depositor and the Indenture Trustee, as trustee, as
amended or supplemented from time to time.

     "Indenture Event of Default" means an "Event of Default" as defined in the
Indenture.

     "Indenture Redemption Date" means, with respect to any Notes to be redeemed
under the Indenture, the date fixed for redemption under the Indenture.

     "Indenture Tax Event" means a "Tax Event" as defined in the Indenture.

     "Indenture Trustee" means [____________], a national banking association
duly organized and existing under the laws of the United States, and any
successor thereto.

     "Lien" means any lien, pledge, charge, encumbrance, mortgage, deed of
trust, adverse ownership interest, hypothecation, assignment, security interest
or preference, priority or other security agreement or preferential arrangement
of any kind or nature whatsoever.

     "Like Amount" means (a) with respect to a redemption of Trust Securities,
Trust Securities having a Liquidation Amount equal to the principal amount of
Notes to be contemporaneously redeemed in accordance with the Indenture the
proceeds of which will be used to pay the Redemption Price of such Trust
Securities, and (b) with respect to a distribution of Notes to Holders of Trust
Securities in connection with a dissolution or liquidation of the Trust, Notes
having a principal

                                       5
<PAGE>

amount equal to the Liquidation Amount of the Trust Securities of the Holder to
whom such Notes are distributed.

     "Liquidation Amount" means the stated amount of $25 per Trust Security.

     "Liquidation Date" means the date on which Notes are to be distributed to
Holders of Trust Securities in connection with a termination and liquidation of
the Trust pursuant to Section 9.4(a).

     "Liquidation Distribution" has the meaning specified in Section 9.4(d).

     "Notes" means the aggregate principal amount of the Depositor's [_____]%
Junior Subordinated Debentures due _______, issued pursuant to the Indenture.

     "1940 Act" means the Investment Company Act of 1940, as amended.

     "Officers' Certificate" means a certificate signed by the Chairman and
Chief Executive Officer, President or a Vice President, and by the Treasurer, an
Associate Treasurer, an Assistant Treasurer, the Controller, the Secretary or an
Assistant Secretary, of the Depositor, and delivered to the appropriate Trustee.
One of the officers signing an Officers' Certificate given pursuant to Section
8.15 shall be the principal executive, financial or accounting officer of the
Depositor. Any Officers' Certificate delivered with respect to compliance with a
condition or covenant provided for in this Trust Agreement shall include:

     (a)  a statement that each officer signing the Officers' Certificate has
read the covenant or condition and the definitions relating thereto;

     (b)  a brief statement of the nature and scope of the examination or
investigation undertaken by each officer in rendering the Officers' Certificate;

     (c)  a statement that each such officer has made such examination or
investigation as, in such officer's opinion, is necessary to enable such officer
to express an informed opinion as to whether or not such covenant or condition
has been complied with; and

     (d)  a statement as to whether, in the opinion of each such officer, such
condition or covenant has been complied with.

     "Opinion of Counsel" means a written opinion of counsel, who may be counsel
the Trust, the Property Trustee or the Depositor, and who shall be reasonably
acceptable to the Property Trustee.

     "Original Trust Agreement" has the meaning specified in the recitals to
this Trust Agreement.

     "Outstanding", when used with respect to Trust Securities, means, as of the
date of determination, all Trust Securities theretofore executed and delivered
under this Trust Agreement, except:

                                       6
<PAGE>

     (a)  Trust Securities theretofore canceled by the Property Trustee or
delivered to the Property Trustee for cancellation;

     (b)  Trust Securities for whose payment or redemption money in the
necessary amount has been theretofore deposited with the Property Trustee or any
Paying Agent for the Holders of such Trust Securities; provided that, if such
Trust Securities are to be redeemed, notice of such redemption has been duly
given pursuant to this Trust Agreement; and

     (c)  Trust Securities which have been paid or in exchange for or in lieu of
which other Preferred Securities have been executed and delivered pursuant to
Sections 5.4, 5.5, 5.11 and 5.13;

provided, however, that in determining whether the Holders of the requisite
Liquidation Amount of the Outstanding Preferred Securities have given any
request, demand, authorization, direction, notice, consent or waiver hereunder,
Preferred Securities owned by the Depositor, any Trustee or any Affiliate of the
Depositor or any Trustee shall be disregarded and deemed not to be Outstanding,
except that (a) in determining whether any Trustee shall be protected in relying
upon any such request, demand, authorization, direction, notice, consent or
waiver, only Preferred Securities that such Trustee knows to be so owned shall
be so disregarded and (b) the foregoing shall not apply at any time when all of
the outstanding Preferred Securities are owned by the Depositor, one or more of
the Trustees and/or any such Affiliate. Preferred Securities so owned which
have been pledged in good faith may be regarded as Outstanding if the pledgee
establishes to the satisfaction of each Administrative Trustee the pledgee's
right so to act with respect to such Preferred Securities and that the pledgee
is not the Depositor or any Affiliate of the Depositor.

     "Owner" means each Person who is the beneficial owner of a Book-Entry
Preferred Securities Certificate as reflected in the records of the Clearing
Agency or, if a Clearing Agency Participant is not the Owner, then as reflected
in the records of a Person maintaining an account with such Clearing Agency
(directly or indirectly, in accordance with the rules of such Clearing Agency).

     "Paying Agent" means any paying agent or co-paying agent appointed pursuant
to Section 5.9 and shall initially be the Bank.

     "Payment Account" means a segregated non-interest-bearing corporate trust
account maintained by the Property Trustee with the Bank in its trust department
for the benefit of the Securityholders in which all amounts paid in respect of
the Notes will be held and from which the Property Trustee, through the Paying
Agent, shall make payments to the Securityholders in accordance with Sections
4.1 and 4.2.

     "Person" means any individual, corporation, partnership, joint venture,
trust, limited liability company or corporation, unincorporated organization or
government or any agency or political subdivision thereof.

     "Preferred Security" means an undivided beneficial interest in the assets
of the Trust, having a Liquidation Amount of $25 and having the rights provided
therefor in this Trust Agreement, including the right to receive Distributions
and a Liquidation Distribution as provided herein.



                                       7
<PAGE>

     "Preferred Securities Certificate" means a certificate evidencing ownership
of Preferred Securities, substantially in the form attached as Exhibit E.

     "Property Trustee" means the Person identified as the "Property Trustee" in
the preamble to this Trust Agreement solely in its capacity as Property Trustee
of the Trust heretofore formed and continued hereunder and not in its individual
capacity, or its successor in interest in such capacity, or any successor
property trustee appointed as herein provided.

     "Redemption Date" means, with respect to any Trust Security to be redeemed.
the date fixed for such redemption by or pursuant to this Trust Agreement;
provided that each Indenture Redemption Date and the stated maturity of the
Notes shall be a Redemption Date for a Like Amount of Trust Securities.

     "Redemption Price" means, with respect to any Trust Security, the
Liquidation Amount of such Trust Security, plus accumulated and unpaid
Distributions to the Redemption Date, allocated on a pro rata basis (based on
Liquidation Amounts) among the Trust Securities.

     "Relevant Trustee" shall have the meaning specified in Section 8.10.

     "Securities Register" and "Securities Registrar" have the respective
meanings specified in Section 5.4.

     "Securityholder" or "Holder" means a Person in whose name a Trust Security
is registered in the Securities Register.  Any such Person shall be deemed to be
a beneficial owner within the meaning of the Delaware Business Trust Act;
provided, however, that in determining whether the Holders of the requisite
amount of Preferred Securities have voted on any matter provided for in this
Trust Agreement, then for the purpose of any such determination, so long as
Definitive Preferred Securities Certificates have not been issued, the term
Securityholders or Holders as used herein shall refer to the Owners.

     "Tax Event" means the receipt by the Trust of an Opinion of Counsel from
counsel experienced in such matters to the effect that, as a result of any
amendment to, or change (including any announced prospective change) in, the
laws (or any regulations thereunder) of the United States or any political
subdivision or taxing authority thereof or therein, or as a result of any
official administrative pronouncement or judicial decision interpreting or
applying such laws or regulations which amendment or change is effective or
which pronouncement or decision is announced on or after the date of issuance of
the Preferred Securities under this Trust Agreement, there is more than an
insubstantial risk that (i) the Trust is, or will be within 90 days after the
date of such Opinion of Counsel, subject to United States federal income tax
with respect to income received or accrued on the Notes, (ii) interest payable
by the Depositor on the Notes is not, or within 90 days after the date of such
Opinion of Counsel, will not be, deductible by the Depositor, in whole or in
part, for United States federal income tax purposes or (iii) the Trust is, or
will be within 90 days after the date of such Opinion of Counsel, subject to
more than a de minimis amount of other taxes, duties, assessments or other
governmental charges.

                                       8
<PAGE>

     "Trust" means the Delaware business trust created and continued hereby and
identified on the cover page of this Trust Agreement.

     "Trust Agreement" means this Amended and Restated Trust Agreement, as the
same may be modified amended or supplemented in accordance with the applicable
provisions hereof, including (i) all exhibits hereto and (ii) for all purposes
of this Trust Agreement and any such modification, amendment or supplement, the
provisions of the Trust Indenture Act that are deemed to be a part of and govern
this Trust Agreement and any such modification, amendment or supplement,
respectively.

     "Trust Indenture Act" means the Trust Indenture Act of 1939 as in force at
the date as of which this instrument was executed; provided, however, that in
the event the Trust Indenture Act of 1939 is amended after such date, "Trust
Indenture Act" means, to the extent required by any such amendment, the Trust
Indenture Act of 1939 as so amended.

     "Trust Property" means (a) the Notes, (b) the rights of the Property
Trustee under the Guarantee, (c) any cash on deposit in, or owing to, the
Payment Account and (d) all proceeds and rights in respect of the foregoing and
any other property and assets for the time being held or deemed to be held by
the Property Trustee pursuant to the trusts of this Trust Agreement.

     "Trust Security" means any one of the Common Securities or the Preferred
Securities.

     "Trust Securities Certificate" means any one of the Common Securities
Certificates or the Preferred Securities Certificates.

     "Trustees" means, collectively, the Property Trustee, the Delaware Trustee
and any Administrative Trustee).

     "Underwriting Agreement" means the Underwriting Agreement dated [______ __]
1999 among the Trust, the Depositor and the underwriters named therein.


                                  ARTICLE II.

                          Establishment Of The Trust

     Section 2.1  Name.

     The Trust continued hereby shall be known as "ONEOK Capital TRUST I," as
such name may be modified from time to time by the Administrative Trustee(s)
following written notice to the Holders of Trust Securities and the other
Trustees, in which name the Trustees may conduct the business of the Trust, make
and execute contracts and other instruments on behalf of the Trust and sue and
be sued.

                                       9
<PAGE>

     Section 2.2  Office of the Delaware Trustee; Principal Place of Business.

     The address of the Delaware Trustee in the State of Delaware is
[____________], [____________], Wilmington, Delaware 19801, or such other
address in the State of Delaware as the Delaware Trustee may designate by
written notice to the Depositor.  The principal executive office of the Trust is
[____________], Wilmington, Delaware 19801.

     Section 2.3  Initial Contribution of Trust Property; Organizational
Expenses.

     The Trustees acknowledge receipt from the Depositor in connection with the
Original Trust Agreement of the sum of $10, which constituted the initial Trust
Property. The Depositor shall pay organizational expenses of the Trust as they
arise or shall, upon request of any Trustee, promptly reimburse such Trustee for
any such expenses paid by such Trustee. The Depositor shall make no claim upon
the Trust Property for the payment of such expenses.

     Section 2.4  Issuance of the Preferred Securities.

     On [_____  __], 1999 the Depositor, on behalf of the Trust and pursuant to
the Original Trust Agreement, executed and delivered the Underwriting Agreement.
Contemporaneously with the execution and delivery of this Trust Agreement, an
Administrative Trustee(s), on behalf of the Trust, shall execute in accordance
with Section 5.2 and deliver to the Underwriters named in the Underwriting
Agreement Preferred Securities Certificates, registered in the name of the
nominee of the initial Clearing Agency, in an aggregate amount of [____________]
Preferred Securities having an aggregate Liquidation Amount of $[____________],
against receipt of such aggregate purchase price of such Preferred Securities of
$[____________], which amount the Administrative Trustee(s) shall promptly
deliver to the Property Trustee.

     Section 2.5  Issuance of the Common Securities; Subscription and Purchase
of Notes.

     Contemporaneously with the execution and delivery of this Trust Agreement,
an Administrative Trustee(s), on behalf of the Trust, shall execute in
accordance with Section 5.2 and deliver to the Depositor Common Securities
Certificates, registered in the name of the Depositor, in an aggregate amount of
[____________] Common Securities having an aggregate Liquidation Amount of
$[____________] against payment by the Depositor of such amount, which amount
such Administrative Trustee(s) shall promptly deliver to the Property Trustee.
Contemporaneously therewith, an Administrative Trustee(s), on behalf of the
Trust, shall subscribe to and purchase from the Depositor Notes, registered in
the name of the Trust and having an aggregate principal amount equal to
$[____________], and, in satisfaction of the purchase price for such Notes, the
Property Trustee, on behalf of the Trust, shall deliver to the Depositor the sum
of $[____________] (being the sum of the amounts delivered to the Property
Trustee pursuant to (i) the second sentence of Section 2.4 and (ii) the first
sentence of this Section 2.5).

     Section 2.6  Declaration of Trust.

     The exclusive purposes and functions of the Trust are (a) to issue and sell
Trust Securities and use the proceeds from such sale to acquire the Notes, and
(b) to engage in only those activities

                                       10
<PAGE>

necessary, appropriate, convenient or incidental thereto. The Depositor hereby
appoints the Trustees as trustees of the Trust, to have all the rights, powers
and duties to the extent set forth herein, and the Trustees hereby accept such
appointment, The Property Trustee hereby declares that it will hold the Trust
Property in trust upon and subject to the conditions set forth herein for the
benefit of the Trust and the Securityholders. The Administrative Trustee(s)
shall have all rights, powers and duties set forth herein and in accordance with
applicable law with respect to accomplishing the purposes of the Trust. The
Delaware Trustee shall not be entitled to exercise any powers, nor shall the
Delaware Trustee have any of the duties and responsibilities, of the Trustees
set forth herein. The Delaware Trustee shall be one of the Trustees of the Trust
for the sole and limited purpose of fulfilling the requirements of Section
3807(a) of the Delaware Business Trust Act.

      Section 2.7  Authorization to Enter into Certain Transactions.

     (a)  The Trustees shall conduct the affairs of the Trust in accordance with
the terms of this Trust Agreement.  Subject to the limitations set forth in
paragraph (b) of this Section, and in accordance with the following provisions
(i) and (ii), the Trustees shall have the authority to enter into all
transactions and agreements determined by the Trustees to be appropriate in
exercising the authority, express or implied, otherwise granted to the Trustees
under this Trust Agreement, and to perform all acts in furtherance thereof,
including without limitation, the following:

          (i)  As among the Trustees, each Administrative Trustee(s) shall have
     the power and authority to act on behalf of the Trust with respect to the
     following matters:

               (A)  the issuance and sale of the Trust Securities;

               (B)  to cause the Trust to enter into, and to execute, deliver
     and perform on behalf of the Trust, the Expense Agreement and the
     Certificate Depository Agreement and such other agreements as may be
     necessary or desirable in connection with the purposes and function of the
     Trust;

               (C)  assisting in the registration of the Preferred Securities
     under the Securities Act of 1933, as amended, and under state securities or
     blue sky laws, and the qualification of this Trust Agreement as a trust
     indenture under the Trust Indenture Act;

               (D)  assisting in the listing of the Preferred Securities upon
     such securities exchange or exchanges as shall be determined by the
     Depositor and the registration of the Preferred Securities under the
     Securities Exchange Act of 1934, as amended, and the preparation and filing
     of all periodic and other reports and other documents pursuant to the
     foregoing;

               (E)  the sending of notices (other than notices of default) and
     other information regarding the Trust Securities and the Notes to the
     Securityholders in accordance with this Trust Agreement;

                                       11
<PAGE>

           (F)  the appointment of a Paying Agent, authenticating agent and
     Securities Registrar in accordance with this Trust Agreement;

           (G)  registering transfer of the Trust Securities in accordance
     with this Trust Agreement;

           (H)  to the extent provided in this Trust Agreement, the winding
     up of the affairs of and liquidation of the Trust and the preparation,
     execution and filing of the certificate of cancellation with the Secretary
     of State of the State of Delaware;

           (I)  unless otherwise determined by the Depositor, the Property
     Trustee or the Administrative Trustee(s), or as otherwise required by the
     Delaware Business Trust Act or the Trust Indenture Act, to execute on
     behalf of the Trust (either acting alone or together with any or all of the
     Administrative Trustee(s)) any documents that the Administrative Trustee(s)
     have the power to execute pursuant to this Trust Agreement; and

           (J)  the taking of any action incidental to the foregoing as the
     Trustees may from time to time determine is necessary or advisable to give
     effect to the terms of this Trust Agreement for the benefit of the
     Securityholders (without consideration of the effect of any such action on
     any particular Securityholder).

     (ii)  As among the Trustees, the Property Trustee shall have the power,
duty and authority to act on behalf of the Trust with respect to the
following matters:

           (A)  the establishment of the Payment Account;

           (B)  the receipt of the Notes;

           (C)  the collection of interest, principal and any other payments
     made in respect of the Notes in the Payment Account;

           (D)  the distribution through the Paying Agent of amounts owed to
     the Securityholders in respect of the Trust Securities;

           (E)  the exercise of all of the rights, powers and privileges of a
     holder of the Notes;

           (F)  the sending of notices of default and other information
     regarding the Trust Securities and the Notes to the Securityholders in
     accordance with this Trust Agreement;

           (G)  the distribution of the Trust Property in accordance with
     the terms of this Trust Agreement;

                                       12
<PAGE>

               (H)   to the extent provided in this Trust Agreement, the winding
          up of the affairs of and liquidation of the Trust and the preparation,
          execution and filing of the certificate of cancellation with the
          Secretary of State of the State of Delaware;

               (I)   after an Event of Default (other than under paragraph (b),
          (c), (d) or (e) of the definition of such term if such Event of
          Default is by or with respect to the Property Trustee) the taking of
          any action incidental to the foregoing as the Property Trustee may
          from time to time determine is necessary or advisable to give effect
          to the terms of this Trust Agreement and protect and conserve the
          Trust Property for the benefit of the Securityholders (without
          consideration of the effect of any such action on any particular
          Securityholder); and

               (J)   except as otherwise provided in this Section 2.7(a)(ii),
          the Property Trustee shall have none of the duties, liabilities,
          powers or the authority of the Administrative Trustee(s) set forth in
          Section 2.7(a)(i).

     (b)  So long as this Trust Agreement remains in effect, the Trust (or the
Trustees acting on behalf of the Trust) shall not undertake any business,
activities or transaction except as expressly provided herein or contemplated
hereby. In particular, the Trustees (acting on behalf of the Trust) shall not
(i) acquire any investments or engage in any activities not authorized by this
Trust Agreement, (ii) sell, assign, transfer, exchange, mortgage, pledge, set-
off or otherwise dispose of any of the Trust Property or interests therein,
including to Securityholders, except as expressly provided herein, (iii) take
any action that would cause the Trust to fail or cease to qualify as a "grantor
trust" for United States Federal income tax purposes, (iv) incur any
indebtedness for borrowed money or issue any other debt or (v) take or consent
to any action that would result in the placement of a Lien on any of the Trust
Property. The Administrative Trustee(s) shall defend all claims and demands of
all Persons at any time claiming any Lien on any of the Trust Property adverse
to the interest of the Trust or the Securityholders in their capacity as
Securityholders.

     (c)  In connection with the issue and sale of the Preferred Securities, the
Depositor shall have the right and responsibility to assist the Trust with
respect to, or effect on behalf of the Trust, the following (and any actions
taken by the Depositor in furtherance of the following prior to the date of this
Trust Agreement are hereby ratified and confirmed in all respects):

          (i)   the preparation and filing by the Trust with the Commission and
     the execution on behalf of the Trust of a registration statement on the
     appropriate form in relation to the Preferred Securities, including any
     amendments thereto;

          (ii)  the determination of the States in which to take appropriate
     action to qualify or register for sale all or part of the Preferred
     Securities and the determination of any and all such acts, other than
     actions which must be taken by or on behalf of the Trust, and the advice to
     the Trustees of actions they must take on behalf of the Trust, and the
     preparation for execution and filing of any documents to be executed and
     filed by the Trust or on behalf of the Trust, as the Depositor deems
     necessary or advisable in order to comply with the applicable laws of any
     such States;

                                       13
<PAGE>

          (iii)  the preparation for filing by the Trust and execution on behalf
     of the Trust of an application to the New York Stock Exchange or any other
     national stock exchange or the Nasdaq National Market for listing upon
     notice of issuance of any Preferred Securities;

          (iv)   the preparation for filing by the Trust with the Commission and
     the execution on behalf of the Trust of a registration statement on Form 8-
     A relating to the registration of the Preferred Securities under Section
     12(b) or 12(g) of the Exchange Act, including any amendments thereto, if
     required;

          (v)    the negotiation of the terms of, and the execution and delivery
     of, the Underwriting Agreement providing for the sale of the Preferred
     Securities; and

          (vi)   the taking of any other actions necessary or desirable to carry
     out any of the foregoing activities.

     (d)  Notwithstanding anything herein to the contrary, the Administrative
Trustee(s) are authorized and directed to conduct the affairs of the Trust and
to operate the Trust so that the Trust will not be deemed to be an "investment
company" required to be registered under the 1940 Act, or fail to be classified
as a grantor trust for United States Federal income tax purposes and so that the
Notes will be treated as indebtedness of the Depositor for United States Federal
income tax purposes. In this connection, the Depositor and the Administrative
Trustee(s) are authorized to take any action, not inconsistent with applicable
law, the Certificate of Trust or this Trust Agreement, that each of the
Depositor and any Administrative Trustee(s) determines in its discretion to be
necessary or desirable for such purposes, as long as such action does not
adversely affect in any material respect the interests of the holders of the
Preferred Securities.

     Section 2.8  Assets of Trust.

     The assets of the Trust shall consist of the Trust Property.

     Section 2.9  Title to Trust Property.

     Legal title to all Trust Property shall be vested at all times in the
Property Trustee (in its capacity as such) and shall be held and administered by
the Property Trustee for the benefit of the Trust and the Securityholders in
accordance with this Trust Agreement.

                                  ARTICLE III.

                                Payment Account

     Section 3.1  Payment Account.

     (a) On or prior to the Closing Date, the Property Trustee shall establish
the Payment Account. The Property Trustee and any agent of the Property Trustee
shall have exclusive control and sole right of withdrawal with respect to the
Payment Account for the purpose of making deposits in and withdrawals from the
Payment Account in accordance with this Trust Agreement. All monies

                                       14
<PAGE>

and other property deposited or held from time to time in the Payment Account
shall be held by the Property Trustee in the Payment Account for the exclusive
benefit of the Securityholders and for distribution as herein provided,
including (and subject to) any priority of payments provided for herein.

     (b)  The Property Trustee shall deposit in the Payment Account, promptly
upon receipt, all payments of principal of or interest on, and any other
payments or proceeds with respect to, the Notes.  Amounts held in the Payment
Account shall not be invested by the Property Trustee pending distribution
thereof.

                                  ARTICLE IV.

                           Distributions; Redemption

     Section 4.1  Distributions.

     (a)  The Trust Securities represent undivided beneficial interests in the
Trust Property, and Distributions (including of Additional Amounts) will be made
on the Trust Securities at the rate and on the dates that payments of interest
(including of Additional Interest, as defined in the Indenture) are made on the
Notes.  Accordingly:

          (i)    Distributions on the Trust Securities shall be cumulative, and
     will accumulate whether or not there are funds of the Trust available for
     the payment of Distributions. Distributions shall accrue from [_____ __],
     1999, and, except in the event (and to the extent) that the Depositor
     exercises its right to defer the payment of interest on the Notes pursuant
     to the Indenture, shall be payable quarterly in arrears on [_________],
     [_________], [_________], and [______] of each year, commencing on [______
     __], 1999. If any date on which a Distribution is otherwise payable on the
     Trust Securities is not a Business Day, then the payment of such
     Distribution shall be made on the next succeeding day that is a Business
     Day (and without any interest or other payment in respect of any such
     delay) except that, if such Business Day is in the next succeeding calendar
     year, payment of such Distribution shall be made on the immediately
     preceding Business Day, in each case with the same force and effect as if
     made on such date (each date on which distributions are payable in
     accordance with this Section 4.1(a), a "Distribution Date").

          (ii)   Assuming payments of interest on the Notes are made when due
     (and before giving effect to Additional Amounts, if applicable),
     Distributions on the Trust Securities shall be payable at a rate of
     [______]% per annum of the Liquidation Amount of the Trust Securities,
     The amount of Distributions payable for any full period shall be computed
     on the basis of a 360-day year of twelve 30-day months. The amount of
     Distributions for any partial period shall be computed on the basis of the
     number of days elapsed in a 360-day year of twelve 30-day months. The
     amount of Distributions payable for any period shall include the Additional
     Amounts, if any.

          (iii)  Distributions on the Trust Securities shall be made by the
     Property Trustee from the Payment Account and shall be payable on each
     Distribution Date only to the extent

                                       15
<PAGE>

     that the Trust has funds then on hand and available in the Payment Account
     for the payment of such Distributions.

     (b)  Distributions on the Trust Securities with respect to a Distribution
Date shall be payable to the Holders thereof as they appear on the Securities
Register for the Trust Securities on the relevant record date, which shall be
one Business Day prior to such Distribution Date; provided, however, that in the
event that the Preferred Securities do not remain in book-entry-only form, the
relevant record date shall be the date 15 days prior to the relevant
Distribution Date.

     Section 4.2  Redemption.

     (a)  On each Indenture Redemption Date and on the stated maturity of the
Notes, the Trust will be required to redeem a Like Amount of Trust Securities at
the Redemption Price.

     (b)  Notice of redemption shall be given by the Property Trustee by first-
class mail, postage prepaid, mailed not less than 30 nor more than 60 days prior
to the Redemption Date to each Holder of Trust Securities to be redeemed, at
such Holder's address appearing in the Security Register.  All notices of
redemption shall state:

          (i)    the Redemption Date;

          (ii)   the Redemption Price;

          (iii)  the CUSIP number;

          (iv)   if less than all the Outstanding Trust Securities are to be
     redeemed, the identification and the total Liquidation Amount of the
     particular Trust Securities to be redeemed; and

          (v)    that on the Redemption Date the Redemption Price will become
     due and payable upon each such Trust Security to be redeemed and that
     Distributions thereon will cease to accrue on and after said date.

     (c)  The Trust Securities redeemed on each Redemption Date shall be
redeemed at the Redemption Price with the proceeds from the contemporaneous
redemption of Notes. Redemptions of the Trust Securities shall be made and the
Redemption Price shall be payable on each Redemption Date only to the extent
that the Trust has funds then on hand and available in the Payment Account for
the payment of such Redemption Price.

     (d)  If the Property Trustee gives a notice of redemption in respect of any
Preferred Securities, then, by 12:00 P.M., New York City time, on the Redemption
Date, subject to Section 4.2(c), the Property Trustee will, so long as the
Preferred Securities are in book-entry-only form, irrevocably deposit with the
Clearing Agency for the Preferred Securities funds sufficient to pay the
applicable Redemption Price and will give such Clearing Agency irrevocable
instructions and authority to pay the Redemption Price to the holders thereof.
If the Preferred Securities are no longer in book-entry-only form, the Property
Trustee, subject to Section 4.2(c), will irrevocably deposit with

                                       16
<PAGE>

the Paying Agent funds sufficient to pay the applicable Redemption Price and
will give the Paying Agent irrevocable instructions and authority to pay the
Redemption Price to the Holders thereof upon surrender of their Preferred
Securities Certificates. Notwithstanding the foregoing, Distributions payable on
or prior to the Redemption Date for any Trust Securities called for redemption
shall be payable to the Holders of such Trust Securities as they appear on the
Register for the Trust Securities on the relevant record dates for the related
Distribution Dates. If notice of redemption shall have been given and funds
deposited as required, then upon the date of such deposit, all rights of
Securityholders holding Trust Securities so called for redemption will cease,
except the right of such Securityholders to receive the Redemption Price and any
Distribution payable on or prior to the Redemption Date, but without interest,
and such Securities will cease to be outstanding. In the event that any date on
which any Redemption Price is payable is not a Business Day, then payment of the
Redemption Price payable on such date will be made on the next succeeding day
that is a Business Day (and without any interest or other payment in respect of
any such delay), except that, if such Business Day falls in the next calendar
year, such payment will be made on the immediately preceding Business Day, in
each case, with the same force and effect as if made on such date. In the event
that payment of the Redemption Price in respect of any Trust Securities called
for redemption is improperly withheld or refused and not paid either by the
Trust or by the Guarantor pursuant to the Guarantee, Distributions on such Trust
Securities will continue to accrue, at the then applicable rate, from the
Redemption Date originally established by the Trust for such Trust Securities to
the date such Redemption Price is actually paid, in which case the actual
payment date will be the date fixed for redemption for purposes of calculating
the Redemption Price.

     (e)  Payment of the Redemption Price on the Trust Securities shall be made
to the recordholders thereof as they appear on the Securities Register for the
Trust Securities on the relevant record date, which shall be one Business Day
prior to the relevant Redemption Date; provided, however, that in the event that
the Preferred Securities do not remain in book-entry-only form, the relevant
record date shall be the date fifteen days prior to the relevant Redemption
Date.

     (f)  Subject to Section 4.3(a), if less than all the Outstanding Trust
Securities are to be redeemed on a Redemption Date, then the aggregate
Liquidation Amount of Trust Securities to be redeemed shall be allocated on a
pro rata basis (based on Liquidation Amounts) among the Common Securities and
the Preferred Securities. The particular Preferred Securities to be redeemed
shall be selected on a pro rata basis (based upon Liquidation Amounts) not more
than 60 days prior to the Redemption Date by the Property Trustee from the
Outstanding Preferred Securities not previously called for redemption, by such
method (including, without limitation, by lot) as the Property Trustee shall
deem fair and appropriate and which may provide for the selection for redemption
of portions (equal to $25 or an integral multiple of $25 in excess thereof) of
the Liquidation Amount of Preferred Securities of a denomination larger than
$25. The Property Trustee shall promptly notify the Security Registrar in
writing of the Preferred Securities selected for redemption and, in the case of
any Preferred Securities selected for partial redemption, the Liquidation Amount
thereof to be redeemed. For all purposes of this Trust Agreement, unless the
context otherwise requires, all provisions relating to the redemption of
Preferred Securities shall relate, in the case of any Preferred Securities
redeemed or to be redeemed only in part, to the portion of the Liquidation
Amount of Preferred Securities that has been or is to be redeemed.

                                   17
<PAGE>

     SECTION 4.3.  Subordination of Common Securities.

     (a)  Payment of Distributions (including Additional Amounts, if applicable)
on, and the Redemption Price of, the Trust Securities, as applicable, shall be
made, subject to Section 4.2(f), pro rata among the Common Securities and the
Preferred Securities based on the Liquidation Amount of the Trust Securities;
provided, however, that if on any Distribution Date or Redemption Date any Event
of Default resulting from a Indenture Event of Default shall have occurred and
be continuing, no payment of any Distribution (including Additional Amounts, if
applicable) on, or Redemption Price of, any Common Security, and no other
payment on account of the redemption, liquidation or other acquisition of Common
Securities, shall be made unless payment in full in cash of all accumulated and
unpaid Distributions (including Additional Amounts, if applicable) on all
Outstanding Preferred Securities for all Distribution periods terminating on or
prior thereto, or in the case of payment of the Redemption Price the full amount
of such Redemption Price on all Outstanding Preferred Securities, shall have
been made or provided for, and all funds immediately available to the Property
Trustee shall first be applied to the payment in full in cash of all
Distributions (including Additional Amounts, if applicable) on, or the
Redemption Price of, Preferred Securities then due and payable.

     (b)  In the case of the occurrence of any Event of Default resulting from
any Indenture Event of Default, the Holder of Common Securities will be deemed
to have waived any right to act with respect to any such Event of Default under
this Trust Agreement until the effect of all such Events of Default with respect
to the Preferred Securities have been cured, waived or otherwise eliminated.
Until any such Event of Default under this Trust Agreement with respect to the
Preferred Securities has been so cured, waived or otherwise eliminated, the
Property Trustee shall act solely on behalf of the Holders of the Preferred
Securities and not the Holder of the Common Securities, and only the Holders of
the Preferred Securities will have the right to direct the Property Trustee to
act on their behalf.

     SECTION 4.4.  Payment Procedures.

     Payments of Distributions (including Additional Amounts, if applicable) in
respect of the Preferred Securities shall be made by check mailed to the address
of the Person entitled thereto as such address shall appear on the Securities
Register or, if the Preferred Securities are held by a Clearing Agency, such
Distributions shall be made to the Clearing Agency in immediately available
funds, which shall credit the relevant Person's accounts at such Clearing Agency
on the applicable Distribution Dates. Payments in respect of the Common
Securities shall be made in such manner as shall be mutually agreed between the
Property Trustee and the Common Securityholder.

     SECTION 4.5.  Tax Returns and Reports.

     The Administrative Trustee(s) shall prepare (or cause to be prepared), at
the Depositor's expense, and file all United States Federal, state and local tax
and information returns and reports required to be filed by or in respect of the
Trust. In this regard, the Administrative Trustee(s) shall (a) prepare and file
(or cause to be prepared and filed) the appropriate Internal Revenue Service
Form required to be filed in respect of the Trust in each taxable year of the
Trust and (b) prepare and furnish (or cause to be prepared and furnished) to
each Securityholder the appropriate Internal Revenue Service form required to be
provided on such form. The Administrative Trustee(s) shall

                                      18
<PAGE>

provide the Depositor and the Property Trustee with a copy of all such returns
and reports promptly after such filing or furnishing. The Trustees shall comply
with United States Federal withholding and backup withholding tax laws and
information reporting requirements with respect to any payments to
Securityholders under the Trust Securities.

     SECTION 4.6.  Payment of Taxes, Duties, Etc. of the Trust.

     Upon receipt under the Notes of Additional Sums, the Property Trustee shall
promptly pay any taxes, duties or governmental charges of whatsoever nature
(other than withholding taxes) imposed on the Trust by the United States or any
other taxing authority.

     SECTION 4.7.  Payments under Indenture or Pursuant to Direct Actions.

     Any amount payable hereunder to any Holder of Preferred Securities (and any
Owner with respect thereto) shall be reduced by the amount of any corresponding
payment such Holder (and Owner) has directly received pursuant to Section 5.8 of
the Indenture or Section 5.14 of this Trust Agreement.

                                   ARTICLE V.

                         Trust Securities Certificates

     SECTION 5.1.  Initial Ownership.

     Upon the formation of the Trust and the contribution by the Depositor
pursuant to Section 2.3 and until the issuance of the Trust Securities, and at
any time during which no Trust Securities are outstanding, the Depositor shall
be the sole beneficial owner of the Trust.

     SECTION 5.2.  The Trust Securities Certificates.

     The Preferred Securities Certificates shall be issued in minimum
denominations of $25 Liquidation Amount and integral multiples of $25 in excess
thereof, and the Common Securities Certificates shall be issued in denominations
of $25 Liquidation Amount and integral multiples thereof. The Trust Securities
Certificates shall be executed on behalf of the Trust by manual signature of at
least one Administrative Trustee(s). Trust Securities Certificates bearing the
manual signatures of individuals who were, at the time when such signatures
shall have been affixed, authorized to sign on behalf of the Trust, shall be
validly issued and entitled to the benefits of this Trust Agreement,
notwithstanding that such individuals or any of them shall have ceased to be so
authorized prior to the delivery of such Trust Securities Certificates or did
not hold such offices at the date of delivery of such Trust Securities
Certificates. A transferee of a Trust Securities Certificate shall become a
Securityholder, and shall be entitled to the rights and subject to the
obligations of a Securityholder hereunder, upon due registration of such Trust
Securities Certificate in such transferee's name pursuant to Sections 5.4, 5.11
and 5.13.

                                      19
<PAGE>

     SECTION 5.3.  Execution and Delivery of Trust Securities Certificates.

     At the Closing Date, the Administrative Trustee(s) shall cause Trust
Securities Certificates, in an aggregate Liquidation Amount as provided in
Sections 2.4 and 2.5, to be executed on behalf of the Trust and delivered to or
upon the written order of the Depositor, signed by its chairman of the board,
its president, any executive vice president or any vice president, treasurer or
assistant treasurer or controller without further corporate action by the
Depositor, in authorized denominations.

     SECTION 5.4.  Registration of Transfer and Exchange of Preferred Securities
                     Certificates.

     The Depositor shall keep or cause to be kept, at the office or agency
maintained pursuant to Section 5.8, a register or registers for the purpose of
registering Trust Securities Certificates and transfers and exchanges of
Preferred Securities Certificates (the "Securities Register") in which, the
registrar designated by the Depositor (the "Securities Registrar"), subject to
such reasonable regulations as it may prescribe, shall provide for the
registration of Preferred Securities Certificates and Common Securities
Certificates (subject to Section 5.10 in the case of the Common Securities
Certificates) and registration of transfers and exchanges of Preferred
Securities Certificates as herein provided. The Bank shall be the initial
Securities Registrar.

     Upon surrender for registration of transfer of any Preferred Securities
Certificate at the office or agency maintained pursuant to Section 5.8, the
Administrative Trustee(s) or any one of them shall execute and deliver, in the
name of the designated transferee or transferees, one or more new Preferred
Securities Certificates in authorized denominations of a like aggregate
Liquidation Amount dated the date of execution by such Administrative Trustee or
Trustees.

     The Securities Registrar shall not be required to register the transfer of
any Preferred Securities that have been called for redemption. At the option of
a Holder, Preferred Securities Certificates may be exchanged for other Preferred
Securities Certificates in authorized denominations of the same class and of a
like aggregate Liquidation Amount upon surrender of the Preferred Securities
Certificates to be exchanged at the office or agency maintained pursuant to
Section 5.8.

     Every Preferred Securities Certificate presented or surrendered for
registration of transfer or exchange shall be accompanied by a written
instrument of transfer in form satisfactory to an Administrative Trustee(s) and
the Securities Registrar duly executed by the Holder or his attorney duly
authorized in writing. Each Preferred Securities Certificate surrendered for
registration of transfer or exchange shall be canceled and subsequently disposed
of by an Administrative Trustee(s) in accordance with such Person's customary
practice.

     No service charge shall be made for any registration of transfer or
exchange of Preferred Securities Certificates, but the Securities Registrar may
require payment of a sum sufficient to cover any tax or governmental charge that
may be imposed in connection with any transfer or exchange of Preferred
Securities Certificates.

     Section 5.5.  Mutilated, Destroyed. Lost or Stolen Trust Securities
                     Certificates.

                                      20
<PAGE>

     If (a) any mutilated Trust Securities Certificate shall be surrendered to
the Securities Registrar, or if the Securities Registrar shall receive evidence
to its satisfaction of the destruction, loss or theft of any Trust Securities
Certificate and (b) there shall be delivered to the Securities Registrar and the
Administrative Trustee(s) such security or indemnity as may be required by them
to save each of them harmless, then in the absence of notice that such Trust
Securities Certificate shall have been acquired by a bona fide purchaser, the
Administrative Trustee(s), or any one of them, on behalf of the Trust shall
execute and make available for delivery, in exchange for or in lieu of any such
mutilated, destroyed, lost or stolen Trust Securities Certificate, a new Trust
Securities Certificate of like class, tenor and denomination. In connection with
the issuance of any new Trust Securities Certificate under this Section, the
Administrative Trustee(s) or the Securities Registrar may require the payment of
a sum sufficient to cover any tax or other governmental charge that may be
imposed in connection therewith. Any duplicate Trust Securities Certificate
issued pursuant to this Section shall constitute conclusive evidence of an
undivided beneficial interest in the assets of the Trust, as if originally
issued, whether or not the lost, stolen or destroyed Trust Securities
Certificate shall be found at any time.

     SECTION 5.6.  Persons Deemed Securityholders.

     The Trustees or the Securities Registrar shall treat the Person in whose
name any Trust Securities Certificate shall be registered in the Securities
Register as the owner of such Trust Securities Certificate for the purpose of
receiving Distributions and for all other purposes whatsoever, and neither the
Trustees nor the Securities Registrar shall be bound by any notice to the
contrary.

     SECTION 5.7.  Access to List of Securityholders' Names and Addresses.

     The Administrative Trustee(s) or the Depositor shall furnish or cause to be
furnished to the Property Trustee (a) semi-annually on or before January 15 and
July 15 in each year, a list, in such form as the Property Trustee may
reasonably require, of the names and addresses of the Securityholders as of the
most recent record date and (b) promptly after receipt by any Administrative
Trustee(s) or the Depositor of a request for such list from the Property Trustee
in order to enable the Property Trustee to discharge its obligations under this
Trust Agreement, a list of the type referred to in clause (a), in each case to
the extent such information is in the possession or control of the
Administrative Trustee(s) or the Depositor and is not identical to a previously
supplied list or has not otherwise been received by the Property Trustee in its
capacity as Securities Registrar. The rights of Securityholders to communicate
with other Securityholders with respect to their rights under this Trust
Agreement or under the Trust Securities, and the corresponding rights of the
Property Trustee shall be as provided in the Trust Indenture Act. Each
Securityholder and each Owner shall be deemed to have agreed not to hold the
Depositor, the Property Trustee or the Administrative Trustee(s) accountable by
reason of the disclosure of its name and address, regardless of the source from
which such information was derived.

     SECTION 5.8.  Maintenance of Office or Agency.

     The Administrative Trustee(s) shall maintain an office or offices or agency
or agencies where Preferred Securities Certificates may be surrendered for
registration of transfer or exchange and where notices and demands to or upon
the Trustees in respect of the Trust Securities Certificates may

                                      21
<PAGE>

be served. The Administrative Trustee(s) initially designate [____________],
[____________], [____________], Attn: [____________], as its principal corporate
trust office for such purposes. The Administrative Trustee(s) shall give prompt
written notice to the Depositor and to the Securityholders of any change in the
location of the Securities Register or any such office or agency.

     SECTION 5.9.   Appointment of Paying Agent.

     The Paying Agent shall make distributions to Securityholders from the
Payment Account and shall report the amounts of such distributions to the
Property Trustee and the Administrative Trustee(s). Any Paying Agent shall have
the revocable power to withdraw funds from the Payment Account for the purpose
of making the distributions referred to above. The Administrative Trustee(s) may
revoke such power and remove the Paying Agent if such Trustees determine in
their sole discretion that the Paying Agent shall have failed to perform its
obligations under this Trust Agreement in any material respect. The Paying Agent
shall initially be the Bank, and any co-paying agent chosen by the Bank, and
acceptable to the Administrative Trustee(s) and the Depositor. Any Person acting
as Paying Agent shall be permitted to resign as Paying Agent upon 30 days'
written notice to the Administrative Trustee(s), the Property Trustee and the
Depositor. In the event that the Bank shall no longer be the Paying Agent or a
successor Paying Agent shall resign or its authority to act be revoked, the
Administrative Trustee(s) shall appoint a successor that is acceptable to the
Property Trustee and the Depositor to act as Paying Agent (which shall be a bank
or trust company). The Administrative Trustee(s) shall cause such successor
Paying Agent or any additional Paying Agent appointed by the Administrative
Trustee(s) to execute and deliver to the Trustees an instrument in which such
successor Paying Agent or additional Paying Agent shall agree with the Trustees
that as Paying Agent, such successor Paying Agent or additional Paying Agent
will hold all sums, if any, held by it for payment to the Securityholders in
trust for the benefit of the Securityholders entitled thereto until such sums
shall be paid to such Securityholders. The Paying Agent shall return all
unclaimed funds to the Property Trustee and upon removal of a Paying Agent such
Paying Agent shall also return all funds in its possession to the Property
Trustee. The provisions of Sections 8.1, 8.3 and 8.6 herein shall apply to the
Bank also in its role as Paying Agent, for so long as the Bank shall act as
Paying Agent and, to the extent applicable, to any other paying agent appointed
hereunder. Any reference in this Agreement to the Paying Agent shall include any
co-paying agent unless the context requires otherwise.

     SECTION 5.10.  Ownership of Common Securities by Depositor.

     On the Closing Date, the Depositor shall acquire and retain beneficial and
record ownership of the Common Securities, To the fullest extent permitted by
law, other than a transfer in connection with a consolidation or merger of the
Depositor into another corporation, or any conveyance, transfer or lease by the
Depositor of its properties and assets substantially as an entirety to any
Person, pursuant to Section 8.1 of the Indenture, any attempted transfer of the
Common Securities shall be void. The Administrative Trustee(s) shall cause each
Common Securities Certificate issued to the Depositor to contain a legend
stating "THIS CERTIFICATE IS NOT TRANSFERABLE EXCEPT IN CERTAIN LIMITED
CIRCUMSTANCES SET FORTH IN THE AMENDED AND RESTATED TRUST AGREEMENT OF ONEOK
CAPITAL TRUST I."

     SECTION 5.11.  Book-Entry Preferred Securities Certificates; Common
                    Securities Certificate.

                                      22
<PAGE>

     (a)  The Preferred Securities Certificates, upon original issuance, will be
issued in the form of a typewritten Preferred Securities Certificate or
Certificates representing Book-Entry Preferred Securities Certificates, to be
delivered to The Depository Trust Company, the initial Clearing Agency, by, or
on behalf of, the Trust. Such Preferred Securities Certificate or Certificates
shall initially be registered on the Securities Register in the name of Cede &
Co., the nominee of the initial Clearing Agency, and no Owner will receive a
Definitive Preferred Securities Certificate representing such Owner's interest
in such Preferred Securities, except as provided in Section 5.13. Unless and
until Definitive Preferred Securities Certificates have been issued to Owners
pursuant to Section 5.13:

          (i)   the provisions of this Section 5.11(a) shall be in full force
     and effect;

          (ii)  the Securities Registrar, the Depositor, the Guarantor, and the
     Trustees shall be entitled to deal with the Clearing Agency for all
     purposes of this Trust Agreement relating to the Book-Entry Preferred
     Securities Certificates (including the payment of the Liquidation Amount of
     and Distributions or Redemption Price on the Preferred Securities evidenced
     by Book-Entry Preferred Securities Certificates and the giving of
     instructions or directions to Owners of Preferred Securities evidenced by
     Book-Entry Preferred Securities Certificates) as the sole Holder of
     Preferred Securities evidenced by Book-Entry Preferred Securities
     Certificates and shall have no obligations to the Owners thereof;

          (iii) to the extent that the provisions of this Section 5.11 conflict
     with any other provisions of this Trust Agreement, the provisions of this
     Section 5.11 shall control; and

          (iv)  the rights of the Owners of the Book-Entry Preferred Securities
     Certificates shall be exercised only through the Clearing Agency and shall
     be limited to those established by law and agreements between such Owners
     and the Clearing Agency and/or the Clearing Agency Participants.  Pursuant
     to the Certificate Depository Agreement, unless and until Definitive
     Preferred Securities Certificates are issued pursuant to Section 5.13, the
     initial Clearing Agency will make book-entry transfers among the Clearing
     Agency Participants and receive and transmit payments on the Preferred
     Securities to such Clearing Agency Participants.

     (b)  A single Common Securities Certificate representing the Common
Securities shall be issued to the Depositor in the form of a definitive Common
Securities Certificate.

     SECTION 5.12.  Notices to Clearing Agency.

     To the extent that a notice or other communication to the Owners is
required under this Trust Agreement, unless and until Definitive Preferred
Securities Certificates shall have been issued to Owners pursuant to Section
5.13, the Trustees shall give all such notices and communications specified
herein to be given to Owners to the Clearing Agency, and shall have no
obligations to the Owners.

     SECTION 5.13.  Definitive Preferred Securities Certificates.

                                      23
<PAGE>

     If (a) the Depositor advises the Trustees in writing that the Clearing
Agency is no longer willing or able to properly discharge its responsibilities
with respect to the Preferred Securities Certificates, and the Depositor is
unable to locate a qualified successor, (b) the Depositor at its option advises
the Trustees in writing that it elects to terminate the book-entry system
through the Clearing Agency or (c) after the occurrence of a Indenture Event of
Default, Owners of Preferred Securities Certificates representing beneficial
interests aggregating at least a majority of the Liquidation Amount advise the
Administrative Trustee(s) in writing that the continuation of a book entry
system through the Clearing Agency is no longer in the best interest of the
Owners of Preferred Securities Certificates, then the Administrative Trustee(s)
shall notify the Clearing Agency and the Clearing Agency shall notify all Owners
of Preferred Securities Certificates and the other Trustees of the occurrence of
any such event and of the availability of the Definitive Preferred Securities
Certificates to Owners of such class or classes, as applicable, requesting the
same. Upon surrender to the Administrative Trustee(s) of the typewritten
Preferred Securities Certificate or Certificates representing the Book Entry
Preferred Securities Certificates by the Clearing Agency, accompanied by
registration instructions, the Administrative Trustee(s), or any one of them,
shall execute the Definitive Preferred Securities Certificates in accordance
with the instructions of the Clearing Agency. Neither the Securities Registrar
nor the Trustees shall be liable for any delay in delivery of such instructions
and may conclusively rely on, and shall be protected in relying on, such
instructions. Upon the issuance of Definitive Preferred Securities Certificates,
the Trustees shall recognize the Holders of the Definitive Preferred Securities
Certificates as Securityholders. The Definitive Preferred Securities
Certificates shall be printed, lithographed or engraved or may be produced in
any other manner as is reasonably acceptable to the Administrative Trustee(s),
as evidenced by the execution thereof by the Administrative Trustee(s) or any
one of them.

     SECTION 5.14.  Rights of Securityholders.

     (a)  The legal title to the Trust Property is vested exclusively in the
Property Trustee (in its capacity as such) in accordance with Section 2.9, and
the Securityholders shall not have any right or title therein other than the
undivided beneficial interest in the assets of the Trust conferred by their
Trust Securities and they shall have no right to call for any partition or
division of property, profits or rights of the Trust except as described below.
The Trust Securities shall be personal property giving only the rights
specifically set forth therein and in this Trust Agreement. The Trust Securities
shall have no preemptive or similar rights and when issued and delivered to
Securityholders against payment of the purchase price therefor will be fully
paid and nonassessable by the Trust. The Holders of the Trust Securities, in
their capacities as such, shall be entitled to the same limitation of personal
liability extended to stockholders of private corporations for profit organized
under the General Corporation Law of the State of Delaware.

     (b)  For so long as any Preferred Securities remain Outstanding, if, upon a
Indenture Event of Default, the Indenture Trustee fails or the holders of not
less than 25% in principal amount of the outstanding Notes fail to declare the
principal of all of the Notes to be immediately due and payable, the Holders of
at least 25% in Liquidation Amount of the Preferred Securities then Outstanding
shall have such right by a notice in writing to the Depositor, the Guarantor and
the Indenture Trustee; and upon any such declaration such principal amount of
and the accrued interest on all of the Notes shall become immediately due and
payable, provided that the payment of principal and interest on such Notes shall
remain subordinated to the extent provided in the Indenture.

                                      24
<PAGE>

     At any time after such a declaration of acceleration with respect to the
Notes has been made and before a judgment or decree for payment of the money due
has been obtained by the Indenture Trustee as in the Indenture provided, the
Holders of a majority in Liquidation Amount of the Preferred Securities, by
written notice to the Property Trustee, the Depositor and the Indenture Trustee,
may rescind and annul such declaration and its consequences if:

          (i) the Depositor has paid or deposited with the Indenture Trustee a
     sum sufficient to pay

               (A) all overdue installments of interest (including any
          Additional Interest (as defined in the Indenture)) on all of the
          Notes,

               (B) the principal of any Notes which have become due otherwise
          than by such declaration of acceleration and interest thereon at the
          rate borne by the Notes, and

               (C) all sums paid or advanced by the Indenture Trustee under the
          Indenture and the reasonable compensation, expenses, disbursements and
          advances of the Indenture Trustee and the Property Trustee, their
          agents and counsel; and

          (ii) all Events of Default with respect to the Notes, other than the
     nonpayment of the principal of the Notes which has become due solely by
     such acceleration, have been cured or waived as provided in Section 5.13 of
     the Indenture.

     The holders of a majority in aggregate liquidation preference of the
Preferred Securities may, on behalf of the Holders of all the Preferred
Securities, waive any past default under the Indenture, except a default in the
payment of principal or interest (unless such default has been cured and a sum
sufficient to pay all matured installments of interest and principal due
otherwise than by acceleration has been deposited with the Indenture Trustee) or
a default in respect of a covenant or provision which under the Indenture cannot
be modified or amended without the consent of the holder of each outstanding
Note.  No such rescission shall affect any subsequent default or impair any
right consequent thereon.

     Upon receipt by the Property Trustee of written notice declaring such an
acceleration, or rescission and annulment thereof, by Holders of the Preferred
Securities all or part of which is represented by Book-Entry Preferred
Securities Certificates, a record date shall be established for determining
Holders of Outstanding Preferred Securities entitled to join in such notice,
which record date shall be at the close of business on the day the Property
Trustee receives such notice.  The Holders on such record date, or their duly
designated proxies, and only such Persons, shall be entitled to join in such
notice, whether or not such Holders remain Holders after such record date;
provided, that, unless such declaration of acceleration, or rescission and
annulment, as the case may be, shall have become effective by virtue of the
requisite percentage having joined in such notice prior to the day which is 90
days after such record date, such notice of declaration of acceleration, or
rescission and annulment, as the case may be, shall automatically and without
further action by any Holder be canceled and of no further effect.  Nothing in
this paragraph shall prevent a Holder, or a proxy of a Holder, from giving,
after expiration of such 90-day period, a new written notice of declaration of

                                       25
<PAGE>

acceleration, or rescission and annulment thereof, as the case may be, that is
identical to a written notice which has been canceled pursuant to the proviso to
the preceding sentence, in which event a new record date shall be established
pursuant to the provisions of this Section 5.14(b).

     (c)  For so long as any Preferred Securities remain Outstanding, to the
fullest extent permitted by law and subject to the terms of this Trust Agreement
and the Indenture, upon a Indenture Event of Default specified in Section 5.1(1)
or 5.1(2) of the Indenture, any Holder of Preferred Securities shall have the
right to institute a proceeding directly against the Depositor, pursuant to
Section 5.8 of the Indenture, for enforcement of payment to such Holder of the
principal amount of or interest on Notes having a principal amount equal to the
Liquidation Amount of the Preferred Securities of such Holder (a "Direct
Action").  Except as set forth in Section 5.14(b) and this Section 5.14(c), the
Holders of Preferred Securities shall have no right to exercise directly any
right or remedy available to the holders of, or in respect of, the Notes.


                                  ARTICLE VI.

                   Acts Of Securityholders; Meetings; Voting

     SECTION 6.1  Limitations on Voting Rights.

     (a)  Except as provided in this Section, in Sections 5.14, 8.10 and 10.2
and in the Indenture and as otherwise required by law, no Holder of Preferred
Securities shall have any right to vote or in any manner otherwise control the
administration, operation and management of the Trust or the obligations of the
parties hereto, nor shall anything herein set forth, or contained in the terms
of the Trust Securities Certificates, be construed so as to constitute the
Securityholders from time to time as partners or members of an association.

     (b) So long as any Notes are held by the Property Trustee, the Trustees
shall not (i) direct the time, method and place of conducting any proceeding for
any remedy available to the Indenture Trustee, or executing any trust or power
conferred on the Indenture Trustee with respect to such Notes, (ii) waive any
past default which is waivable under Section 5.13 of the Indenture, (iii)
exercise any right to rescind or annul a declaration that the principal of all
the Notes shall be due and payable or (iv) consent to any amendment,
modification or termination of the Indenture or the Notes, where such consent
shall be required, without, in each case, obtaining the prior approval of the
Holders of a majority in Liquidation Amount of all Outstanding Preferred
Securities, provided, however, that where a consent under the Indenture would
require the consent of each Holder of Notes affected thereby, no such consent
shall be given by the Property Trustee without the prior written consent of each
Holder of Preferred Securities.  The Trustees shall not revoke any action
previously authorized or approved by a vote of the Holders of Preferred
Securities, except by a subsequent vote of the Holders of Preferred Securities.
The Property Trustee shall notify all Holders of the Preferred Securities of any
notice of default received from the Indenture Trustee with respect to the Notes.
In addition to obtaining the foregoing approvals of the Holders of the Preferred
Securities, prior to taking any of the foregoing actions, the Trustees shall, at
the expense of the Depositor, obtain an Opinion of Counsel experienced in such
matters to the effect that such action shall not cause the Trust to fail to be
classified as a grantor trust for United States Federal income tax purposes.

                                       26
<PAGE>

     (c)  If any proposed amendment to the Trust Agreement provides for, or the
Trustees otherwise propose to effect, (i) any action that would adversely affect
in any material respect the powers, preferences or special rights of the
Preferred Securities, whether by way of amendment to the Trust Agreement or
otherwise, or (ii) the dissolution, winding-up or termination of the Trust,
other than pursuant to the terms of this Trust Agreement, then the Holders of
Outstanding Preferred Securities as a class will be entitled to vote on such
amendment or proposal and such amendment or proposal shall not be effective
except with the approval of the Holders of at least a majority in Liquidation
Amount of the Outstanding Preferred Securities.  Notwithstanding any other
provision of this Trust Agreement, no amendment to this Trust Agreement may be
made if, as a result of such amendment, it would cause the Trust to fail to be
classified as a grantor trust for United States Federal income tax purposes.

     SECTION 6.2  Notice of Meetings.

     Notice of all meetings of the Preferred Securityholders, stating the time,
place and purpose of the meeting, shall be given by the Property Trustee
pursuant to Section 10.8 to each Preferred Securityholder of record, at his
registered address, at least 15  days and not more than 90 days before the
meeting.  At any such meeting, any business properly before the meeting may be
so considered whether or not stated in the notice of the meeting.  Any adjourned
meeting may be held as adjourned without further notice.

     SECTION 6.3  Meetings of Preferred Securityholders.

     No annual meeting of Securityholders is required to be held.  The
Administrative Trustee(s), however, shall call a meeting of Preferred
Securityholders to vote on any matter upon the written request of the Preferred
Securityholders of record of 25% of the Preferred Securities (based upon their
Liquidation Amount) and the Administrative Trustee(s) or the Property Trustee
may, at any time in their discretion, call a meeting of Preferred
Securityholders to vote on any matters as to which Preferred Securityholders are
entitled to vote.

     Preferred Securityholders of record of 50% of the Outstanding Preferred
Securities (based upon their Liquidation Amount), present in person or by proxy,
shall constitute a quorum at any meeting of Securityholders.

     If a quorum is present at a meeting, an affirmative vote by the Preferred
Securityholders of record present, in person or by proxy, holding more than a
majority of the Preferred Securities (based upon their Liquidation Amount) held
by the Preferred Securityholders of record present, either in person or by
proxy, at such meeting shall constitute the action of the Preferred
Securityholders, unless this Trust Agreement requires a greater number of
affirmative votes.

     SECTION 6.4  Voting Rights.

     Securityholders shall be entitled to one vote for each $25 of Liquidation
Amount represented by their Trust Securities in respect of any matter as to
which such Securityholders are entitled to vote.

     SECTION 6.5  Proxies, etc.

                                       27
<PAGE>

     At any meeting of Securityholders, any Securityholder entitled to vote
thereat may vote by proxy, provided that no proxy shall be voted at any meeting
unless it shall have been placed on file with the Administrative Trustee(s), or
with such other officer or agent of the Trust as the Administrative Trustee(s)
may direct, for verification prior to the time at which such vote shall be
taken. Pursuant to a resolution of the Property Trustee, proxies may be
solicited in the name of the Property Trustee or one or more officers of the
Property Trustee. Only Securityholders of record shall be entitled to vote. When
Trust Securities are held jointly by several persons, any one of them may vote
at any meeting in person or by proxy in respect of such Trust Securities, but if
more than one of them shall be present at such meeting in person or by proxy,
and such joint owners or their proxies so present disagree as to any vote to be
cast, such vote shall not be received in respect of such Trust Securities. A
proxy purporting to be executed by or on behalf of a Securityholder shall be
deemed valid unless challenged at or prior to its exercise, and the burden of
proving invalidity shall rest on the challenger. No proxy shall be valid more
than three years after its date of execution.

     SECTION 6.6  Securityholder Action by Written Consent.

     Any action which may be taken by Securityholders at a meeting may be taken
without a meeting if Securityholders holding more than a majority of all
Outstanding Trust Securities (based upon their Liquidation Amount) entitled to
vote in respect of such action (or such larger proportion thereof as shall be
required by any express provision of this Trust Agreement) shall consent to the
action in writing.

     SECTION 6.7  Record Date for Voting and Other Purposes.

     For the purposes of determining the Securityholders who are entitled to
notice of and to vote at any meeting or by written consent, or to participate in
any distribution on the Trust Securities in respect of which a record date is
not otherwise provided for in this Trust Agreement, or for the purpose of any
other action, the Administrative Trustee(s) may from time to time fix a date,
not more than 90 days prior to the date of any meeting of Securityholders or the
payment of a distribution or other action, as the case may be, as a record date
for the determination of the identity of the Securityholders of record for such
purposes.

     SECTION 6.8  Acts of Securityholders.

     Any request, demand, authorization, direction, notice, consent, waiver or
other action provided or permitted by this Trust Agreement to be given, made or
taken by Securityholders or Owners may be embodied in and evidenced by one or
more instruments of substantially similar tenor signed by such Securityholders
or Owners in person or by an agent duly appointed in writing; and, except as
otherwise expressly provided herein, such action shall become effective when
such instrument or instruments are delivered to an Administrative Trustee(s).
Such instrument or instruments (and the action embodied therein and evidenced
thereby) are herein sometimes referred to as the "Act" of the Securityholders or
Owners signing such instrument or instruments.  Proof of execution of any such
instrument or of a writing appointing any such agent shall be sufficient for any
purpose of this Trust Agreement and (subject to Section 8.1) conclusive in favor
of the Trustees, if made in the manner provided in this Section.

                                       28
<PAGE>

     The fact and date of the execution by any Person of any such instrument or
writing may be proved by the affidavit of a witness of such execution or by a
certificate of a notary public or other officer authorized by law to take
acknowledgments of deeds, certifying that the individual signing such instrument
or writing acknowledged to him the execution thereof.  Where such execution is
by a signer acting in a capacity other than his individual capacity, such
certificate or affidavit shall also constitute sufficient proof of his
authority.  The fact and date of the execution of any such instrument or
writing, or the authority of the Person executing the same, may also be proved
in any other manner which any Trustee receiving the same deems sufficient.

     The ownership of Preferred Securities shall be proved by the Securities
     Register.

     Any request, demand, authorization, direction, notice, consent, waiver or
other Act of the Securityholder of any Trust Security shall bind every future
Securityholder of the same Trust Security and the Securityholder of every Trust
Security issued upon the registration of transfer thereof or in exchange
therefor or in lieu thereof in respect of anything done, omitted or suffered to
be done by the Trustees or the Trust in reliance thereon, whether or not
notation of such action is made upon such Trust Security.

     Without limiting the foregoing, a Securityholder entitled hereunder to take
any action hereunder with regard to any particular Trust Security may do so with
regard to all or any part of the Liquidation Amount of such Trust Security or by
one or more duly appointed agents each of which may do so pursuant to such
appointment with regard to all or any part of such liquidation amount.

     If any dispute shall arise between the Securityholders and the
Administrative Trustee(s) or among such Securityholders or Trustees with respect
to the authenticity, validity or binding nature of any request, demand,
authorization, direction, consent, waiver or other Act of such Securityholder or
Trustee under this Article VI, then the determination of such matter by the
Property Trustee shall be conclusive with respect to such matter.

     A Securityholder may institute a legal proceeding directly against the
Guarantor under the Guarantee to enforce its rights under the Guarantee without
first instituting a legal proceeding against the Guarantee Trustee (as defined
in the Guarantee), the Trust or any person or entity.

     SECTION 6.9  Inspection of Records.

     Upon reasonable notice to the Administrative Trustee(s) and the Property
Trustee, the records of the Trust shall be open to inspection by Securityholders
during normal business hours for any purpose reasonably related to such
Securityholder's interest as a Securityholder.

                                       29
<PAGE>

                                  ARTICLE VII

                        Representations and Warranties

     SECTION 7.1  Representations and Warranties of the Property Trustee and
the Delaware Trustee.

     The Property Trustee and the Delaware Trustee, each severally on behalf of
and as to itself, hereby represents and warrants for the benefit of the
Depositor and the Securityholders that:

     (a)  the Property Trustee is a national banking association duly organized,
validly existing and in good standing under the laws of the United States;

     (b)  the Property Trustee has full corporate power, authority and legal
right to execute, deliver and perform its obligations under this Trust Agreement
and has taken all necessary action to authorize the execution, delivery and
performance by it of this Trust Agreement;

     (c)  the Delaware Trustee is a Delaware corporation duly created, validly
existing and in good standing in the State of Delaware;

     (d)  the Delaware Trustee has full corporate power, authority and legal
right to execute, deliver and perform its obligations under this Trust Agreement
and has taken all necessary action to authorize the execution, delivery and
performance by it of this Trust Agreement;

     (e)  this Trust Agreement has been duly authorized, executed and delivered
by the Property Trustee and the Delaware Trustee and constitutes the valid and
legally binding agreement of each of the Property Trustee and the Delaware
Trustee enforceable against each of them in accordance with its terms, subject
to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and
similar laws of general applicability relating to or affecting creditor's rights
and to general equity principles;

     (f)  the execution, delivery and performance of this Trust Agreement has
been duly authorized by all necessary corporate or other action on the part of
the Property Trustee and the Delaware Trustee and does not require any approval
of stockholders of the Property Trustee and the Delaware Trustee and such
execution, delivery and performance will not (i) violate the Charter or By-laws
of the Property Trustee or the Delaware Trustee, (ii) violate any provision of,
or constitute, with or without notice or lapse of time, a default under, or
result in the creation or imposition of, any Lien on any properties included in
the Trust Property pursuant to the provisions of, any indenture, mortgage,
credit agreement, license or other agreement or instrument to which the Property
Trustee or the Delaware Trustee is a party or by which it is bound, or (iii)
violate any law, governmental rule or regulation of the United States or the
State of Delaware, as the case may be, governing the banking, trust or general
powers of the Property Trustee or the Delaware Trustee (as appropriate in
context) or any order, judgment or decree applicable to the Property Trustee or
the Delaware Trustee;

                                       30
<PAGE>

     (g)  neither the authorization, execution or delivery by the Property
Trustee or the Delaware Trustee of this Trust Agreement nor the consummation of
any of the transactions by the Property Trustee or the Delaware Trustee (as
appropriate in context) contemplated herein or therein requires the consent or
approval of, the giving of notice to, the registration with or the taking of any
other action with respect to any governmental authority or agency under any
existing Federal law governing the banking, trust or general powers of the
Property Trustee or the Delaware Trustee, as the case may be, under the laws of
the United States or the State of Delaware;

     (h)  there are no proceedings pending or, to the best of each of the
Property Trustee's and the Delaware Trustee's knowledge, threatened against or
affecting the Property Trustee or the Delaware Trustee in any court or before
any governmental authority, agency or arbitration board or tribunal which,
individually or in the aggregate, would materially and adversely affect the
Trust or would question the right, power and authority of the Property Trustee
or the Delaware Trustee, as the case may be, to enter into or perform its
obligations as one of the Trustees under this Trust Agreement.

     SECTION 7.2  Representations and Warranties of Depositor.

     The Depositor hereby represents and warrants for the benefit of the
     Securityholders that:

     (a)  the Trust Securities Certificates issued on the Closing Date on behalf
of the Trust have been duly authorized and will have been, duly and validly
executed, issued and delivered by the Trustees pursuant to the terms and
provisions of, and in accordance with the requirements of, this Trust Agreement
and the Securityholders will be, as of each such date, entitled to the benefits
of this Trust Agreement; and

     (b)  there are no taxes, fees or other governmental charges payable by the
Trust (or the Trustees on behalf of the Trust) under the laws of the State of
Delaware or any political subdivision thereof in connection with the execution,
delivery and performance by the Property Trustee or the Delaware Trustee, as the
case may be, of this Trust Agreement.


                                  ARTICLE VII

                                 The Trustees

     SECTION 8.1  Certain Duties and Responsibilities.

     (a)  The duties and responsibilities of the Trustees shall be as provided
by this Trust Agreement and, in the case of the Property Trustee, subject to the
Trust Indenture Act. Notwithstanding the foregoing, no provision of this Trust
Agreement shall require the Trustees to expend or risk their own funds or
otherwise incur any financial liability in the performance of any of their
duties hereunder, or in the exercise of any of their rights or powers, if they
shall have reasonable grounds for believing that repayment of such funds or
adequate indemnity against such risk or liability is not reasonably assured to
them. Whether or not therein expressly so provided, every provision of this
Trust Agreement relating to the conduct or affecting the liability of or
affording protection to the

                                       31
<PAGE>

Trustees shall be subject to the provisions of this Section. Nothing in this
Trust Agreement shall be construed to release a Trustee from liability for its
own gross negligent action, its own gross negligent failure to act, or its own
willful misconduct. To the extent that, at law or in equity, a Trustee has
duties (including fiduciary duties) and liabilities relating thereto to the
Trust or to the Securityholders, such Trustee shall not be liable to the Trust
or to any Securityholder for such Trustee's good faith reliance on the
provisions of this Trust Agreement. The provisions of this Trust Agreement, to
the extent that they restrict the duties and liabilities of the Trustees
otherwise existing at law or in equity, are agreed by the Depositor and the
Securityholders to replace such other duties and liabilities of the Trustees.

     (b)  All payments made by the Property Trustee or a Paying Agent in respect
of the Trust Securities shall be made only from the revenue and proceeds from
the Trust Property and only to the extent that there shall be sufficient revenue
or proceeds from the Trust Property to enable the Property Trustee or a Paying
Agent to make payments in accordance with the terms hereof.  Each
Securityholder, by its acceptance of a Trust Security, agrees that it will look
solely to the revenue and proceeds from the Trust Property to the extent legally
available for distribution to it as herein provided and that the Trustees are
not personally liable to it for any amount distributable in respect of any Trust
Security or for any other liability in respect of any Trust Security.  This
Section 8.1(b) does not limit the liability of the Trustees expressly set forth
elsewhere in this Trust Agreement or, in the case of the Property Trustee, in
the Trust Indenture Act.

     (c)  No provision of this Trust Agreement shall be construed to relieve the
Property Trustee from liability for its own negligent action, its own negligent
failure to act, or its own willful misconduct, except that:

          (i)  the Property Trustee shall not be liable for any error of
     judgment made in good faith by an authorized officer of the Property
     Trustee, unless it shall be proved that the Property Trustee was negligent
     in ascertaining the pertinent facts;

          (ii) the Property Trustee shall not be liable with respect to any
     action taken or omitted to be taken by it in good faith in accordance with
     the direction of the Holders of not less than a majority in Liquidation
     Amount of the Trust Securities relating to the time, method and place of
     conducting any proceeding for any remedy available to the Property Trustee,
     or exercising any trust or power conferred upon the Property Trustee under
     this Trust Agreement;

          (ii) the Property Trustee's sole duty with respect to the custody,
     safekeeping and physical preservation of the Notes and the Payment Account
     shall be to deal with such Property in a similar manner as the Property
     Trustee deals with similar property for its own account, subject to the
     protections and limitations on liability afforded to the Property Trustee
     under this Trust Agreement and the Trust Indenture Act;

          (iv) the Property Trustee shall not be liable for any interest on any
     money received by it except as it may otherwise agree with the Depositor;
     and money held by the Property Trustee need not be segregated from other
     funds held by it except in relation to the Payment

                                       32
<PAGE>

     Account maintained by the Property Trustee pursuant to Section 3.1 and
     except to the extent otherwise required by law; and

          (v)  the Property Trustee shall not be responsible for monitoring the
     compliance by the Administrative Trustee(s) or the Depositor with their
     respective duties under this Trust Agreement, nor shall the Property
     Trustee be liable for the default or misconduct of the Administrative
     Trustee(s) or the Depositor.

     SECTION 8.2.   Certain Notices.

     Within 90 days after the occurrence of any Event of Default actually known
to the Property Trustee, the Property Trustee shall transmit, in the manner and
to the extent provided in Section 10.8, notice of such Event of Default to the
Securityholders, the Administrative Trustee(s) and the Depositor, unless such
Event of Default shall have been cured or waived.

     Within five Business Days after the receipt of notice of the Depositor's
exercise of its right to defer the payment of interest on the Notes pursuant to
the Indenture, the Administrative Trustee(s) shall transmit, in the manner and
to the extent provided in Section 10.8, notice of such exercise to the
Securityholders and the Property Trustee, unless such exercise shall have been
revoked.

     SECTION 8.3.   Certain Rights of Property Trustee.

     Subject to the provisions of Section 8.1:

     (a)  the Property Trustee may rely and shall be protected in acting or
refraining from acting in good faith upon any resolution, Opinion of Counsel,
certificate, written representation of a Holder or transferee, certificate of
auditors or any other certificate, statement, instrument, opinion, report,
notice, request, consent, order, appraisal, bond, debenture, note, other
evidence of indebtedness or other paper or document believed by it to be genuine
and to have been signed or presented by the proper party or parties;

     (b)  if (i) in performing its duties under this Trust Agreement the
Property Trustee is required to decide between alternative courses of action or
(ii) in construing any of the provisions of this Trust Agreement the Property
Trustee finds the same ambiguous or inconsistent with any other provisions
contained herein or (iii) the Property Trustee is unsure of the application of
any provision of this Trust Agreement, then, except as to any matter as to which
the Preferred Securityholders are entitled to vote under the terms of this Trust
Agreement, the Property Trustee shall deliver a notice to the Depositor
requesting written instructions of the Depositor as to the course of action to
be taken and the Property Trustee shall take such action, or refrain from taking
such action, as the Property Trustee shall be instructed in writing to take, or
to refrain from taking, by the Depositor; provided, however, that if the
Property Trustee does not receive such instructions of the Depositor within ten
Business Days after it has delivered such notice, or such reasonably shorter
period of time set forth in such notice (which to the extent practicable shall
not be less than two Business Days), it may, but shall be under no duty to, take
or refrain from taking such action not inconsistent with this Trust Agreement as
it shall deem advisable and in the best interests of the Securityholders, in
which

                                       33
<PAGE>

event the Property Trustee shall have no liability except for its own bad faith,
negligence or willful misconduct;

     (c)  any direction or act of the Depositor or the Administrative Trustee(s)
contemplated by this Trust Agreement shall be sufficiently evidenced by an
Officers' Certificate;

     (d)  whenever in the administration of this Trust Agreement, the Property
Trustee shall deem it desirable that a matter be established before undertaking,
suffering or omitting any action hereunder, the Property Trustee (unless other
evidence is herein specifically prescribed) may, in the absence of bad faith on
its part, request and rely upon an Officer's Certificate which, upon receipt of
such request, shall be promptly delivered by the Depositor or the Administrative
Trustee(s);

     (e)  the Property Trustee shall have no duty to see to any recording,
filing or registration of any instrument (including any financing or
continuation statement or any filing under tax or securities laws) or any
rerecording, refiling or reregistration thereof;

     (f)  the Property Trustee may consult with counsel (which counsel may be
counsel to the Depositor or any of its Affiliates, and may include any of its
employees) and the advice of such counsel or any Opinion of Counsel shall be
full and complete authorization and protection in respect of any action taken,
suffered or omitted by it hereunder in good faith and in reliance thereon and in
accordance with such advice, such counsel may be counsel to the Depositor or any
of its Affiliates, and may include any of its employees; the Property Trustee
shall have the right at any time to seek instructions concerning the
administration of this Trust Agreement from any court of competent jurisdiction;

     (g)  the Property Trustee shall be under no obligation to exercise any of
the rights or powers vested in it by this Trust Agreement at the request or
direction of any of the Securityholders pursuant to this Trust Agreement, unless
such Securityholders shall have offered to the Property Trustee reasonable
security or indemnity against the costs, expenses and liabilities which might be
incurred by it in compliance with such request or direction;

     (h)  the Property Trustee shall not be bound to make any investigation into
the facts or matters stated in any resolution, certificate, statement,
instrument, opinion, report, notice, request, consent, order, approval, bond,
debenture, note or other evidence of indebtedness or other paper or document,
unless requested in writing to do so by one or more Securityholders, but the
Property Trustee may make such further inquiry or investigation into such facts
or matters as it may see fit;

     (i)  the Property Trustee may execute any of the trusts or powers hereunder
or perform any duties hereunder either directly or by or through its agents or
attorneys, provided that the Property Trustee shall be responsible for its own
negligence or recklessness with respect to selection of any agent or attorney
appointed by it hereunder;

     (j)  whenever in the administration of this Trust Agreement the Property
Trustee shall deem it desirable to receive instructions with respect to
enforcing any remedy or right or taking any other action hereunder the Property
Trustee (i) may request instructions from the Holders of the Trust Securities
which instructions may only be given by the Holders of the same proportion in

                                       34
<PAGE>

Liquidation Amount of the Trust Securities as would be entitled to direct the
Property Trustee under the terms of the Trust Securities in respect of such
remedy, right or action, (ii) may refrain from enforcing such remedy or right or
taking such other action until such instructions are received, and (iii) shall
be protected in acting in accordance with such instructions; and

     (k)  except as otherwise expressly provided by this Trust Agreement, the
Property Trustee shall not be under any obligation to take any action that is
discretionary under the provisions of this Trust Agreement.

     No provision of this Trust Agreement shall be deemed to impose any duty or
obligation on the Property Trustee to perform any act or acts or exercise any
right, power, duty or obligation conferred or imposed on it, in any jurisdiction
in which it shall be illegal, or in which the Property Trustee shall be
unqualified or incompetent in accordance with applicable law, to perform any
such act or acts, or to exercise any such right, power, duty or obligation.  No
permissive power or authority available to the Property Trustee shall be
construed to be a duty.

     SECTION 8.4.   Not Responsible for Recitals or Issuance of Securities.

     The recitals contained herein and in the Trust Securities Certificates
shall be taken as the statements of the Depositor, and the Trustees do not
assume any responsibility for their correctness. The Trustees shall not be
accountable for the use or application by the Depositor of the proceeds of the
Notes .

     SECTION 8.5.   May Hold Securities.

     Except as provided in the definition of the term "Outstanding" in Article
I, any Trustee or any other agent of any Trustee or the Trust, in its individual
or any other capacity, may become the owner or pledgee of Trust Securities and,
subject to Sections 8.8 and 8.13, may otherwise deal with the Trust with the
same rights it would have if it were not a Trustee or such other agent.

     SECTION 8.6.   Compensation; Indemnity; Fees.

     The Depositor agrees:

     (a)  to pay to the Trustees from time to time reasonable compensation for
all services rendered by them hereunder (which compensation shall not be limited
by any provision of law in regard to the compensation of a trustee of an express
trust);

     (b)  except as otherwise expressly provided herein, to reimburse the
Trustees upon request for all reasonable expenses, disbursements and advances
incurred or made by the Trustees in accordance with any provision of this Trust
Agreement (including the reasonable compensation and the expenses and
disbursements of its agents and counsel), except any such expense, disbursement
or advance as may be attributable to its negligence or bad faith; and

     (c)  to the fullest extent permitted by applicable law, to indemnify and
hold harmless (i) each Trustee, (ii) any Affiliate of any Trustee, (iii) any
officer, director, shareholder, employee,

                                       35
<PAGE>

representative or agent of any Trustee, and (iv) any employee or agent of the
Trust or its Affiliates, (referred to herein as an "Indemnified Person") from
and against any loss, damage, liability, tax, penalty, expense or claim of any
kind or nature whatsoever incurred by such Indemnified Person by reason of the
creation, operation or termination of the Trust or any act or omission performed
or omitted by such Indemnified Person in good faith on behalf of the Trust and
in a manner such Indemnified Person reasonably believed to be within the scope
of authority conferred on such Indemnified Person by this Trust Agreement,
except that no Indemnified Person shall be entitled to be indemnified in respect
of any loss, damage or claim incurred by such Indemnified Person by reason of
negligence or willful misconduct with respect to such acts or omissions.

     The provisions of this Section 8.6 shall survive the termination of this
Trust Agreement or the resignation or removal of any Trustee.

     No Trustee may claim any lien or charge on any Trust Property as a result
of any amount due pursuant to this Section 8.6.

     The Depositor and any Trustee may engage in or possess an interest in other
business ventures of any nature or description, independently or with others,
similar or dissimilar to the business of the Trust, and the Trust and the
Holders of Trust Securities shall have no rights by virtue of this Trust
Agreement in and to such independent ventures or the income or profits derived
therefrom, and the pursuit of any such venture, even if competitive with the
business of the Trust, shall not be deemed wrongful or improper.  Neither the
Depositor, nor any Trustee, shall be obligated to present any particular
investment or other opportunity to the Trust even if such opportunity is of a
character that, if presented to the Trust, could be taken by the Trust, and the
Depositor or any Trustee shall have the right to take for its own account
(individually or as a partner or fiduciary) or to recommend to others any such
particular investment or other opportunity.  Any Trustee may engage or be
interested in any financial or other transaction with the Depositor or any
Affiliate of the Depositor, or may act as depository for, trustee or agent for,
or act on any committee or body of holders of, securities or other obligations
of the Depositor or its Affiliates.

     SECTION 8.7.   Corporate Property Trustee Required; Eligibility of
                    Trustees.

     (a)  There shall at all times be a Property Trustee hereunder. The Property
Trustee shall be a Person that is eligible pursuant to the Trust Indenture Act
to act as such and has a combined capital and surplus of at least $50,000,000.
If any such Person publishes reports of condition at least annually, pursuant to
law or to the requirements of its supervising or examining authority, then for
the purposes of this Section, the combined capital and surplus of such Person
shall be deemed to be its combined capital and surplus as set forth in its most
recent report of condition so published. If at any time the Property Trustee
with respect to the Trust Securities shall cease to be eligible in accordance
with the provisions of this Section, it shall resign immediately in the manner
and with the effect hereinafter specified in this Article.

     (b)  There shall at all times be one or more Administrative Trustee(s)
hereunder. Each Administrative Trustee(s) shall be either a natural person who
is at least 21 years of age or a legal entity that shall act through one or more
persons authorized to bind that entity.

                                       36
<PAGE>

     (c)  There shall at all times be a Delaware Trustee. The Delaware Trustee
shall either be (i) a natural person who is at least 21 years of age and a
resident of the State of Delaware or (ii) a legal entity with its principal
place of business in the State of Delaware and that otherwise meets the
requirements of applicable Delaware law that shall act through one or more
persons authorized to bind such entity.

     SECTION 8.8.   Conflicting Interests.

     If the Property Trustee has or shall acquire a conflicting interest within
the meaning of the Trust Indenture Act, the Property Trustee shall either
eliminate such interest or resign, to the extent and in the manner provided by,
and subject to the provisions of, the Trust Indenture Act and this Trust
Agreement.  The Indenture and the guarantee are hereby excluded for purposes of
Section 310(b)(1) of the Trust Indenture Act.

     SECTION 8.9.   Co-Trustees and Separate Trustee.

     Unless an Event of Default shall have occurred and be continuing, at any
time or times, for the purpose of meeting the legal requirements of the Trust
Indenture Act or of any jurisdiction in which any part of the Trust Property may
at the time be located, the Depositor and the Administrative Trustee(s), by
agreed action of the majority of such Trustees, shall have power to appoint, and
upon the written request of the Administrative Trustee(s), the Depositor shall
for such purpose join with the Administrative Trustee(s) in the execution,
delivery, and performance of all instruments and agreements necessary or proper
to appoint, one or more Persons approved by the Property Trustee either to act
as co-trustee, jointly with the Property Trustee, of all or any part of such
Trust Property, or to the extent required by law to act as separate trustee of
any such property, in either case with such powers as may be provided in the
instrument of appointment, and to vest in such Person or Persons in the capacity
aforesaid, any property, title, right or power deemed necessary or desirable,
subject to the other provisions of this section.  If the Depositor does not join
in such appointment within 15 days after the receipt by it of a request so to
do, or in case a Indenture Event of Default has occurred and is continuing, the
Property Trustee alone shall have power to make such appointment. Any co-trustee
or separate trustee appointed pursuant to this Section shall either be (i) a
natural person who is at least 21 years of age and a resident of the United
States or (ii) a legal entity with its principal place of business in the United
States that shall act through one or more persons authorized to bind such
entity.

     Should any written instrument from the Depositor be required by any co-
trustee or separate trustee so appointed for more fully confirming to such co-
trustee or separate trustee such property, title, right, or power, any and all
such instruments shall, on request, be executed, acknowledged and delivered by
the Depositor.

     Every co-trustee or separate trustee shall, to the extent permitted by law,
but to such extent only, be appointed subject to the following terms, namely:

     (a) The Trust Securities shall be executed and delivered and all rights,
powers, duties, and obligations hereunder in respect of the custody of
securities, cash and other personal property held

                                       37
<PAGE>

by, or required to be deposited or pledged with, the Trustees specified
hereunder shall be exercised solely by such Trustees and not by such co-trustee
or separate trustee.

     (b)  The rights, powers, duties, and obligations hereby conferred or
imposed upon the Property Trustee in respect of any property covered by such
appointment shall be conferred or imposed upon and exercised or performed by the
Property Trustee or by the Property Trustee and such co-trustee or separate
trustee jointly, as shall be provided in the instrument appointing such co-
trustee or separate trustee, except to the extent that under any law of any
jurisdiction in which any particular act is to be performed, the Property
Trustee shall be incompetent or unqualified to perform such act, in which event
such rights, powers, duties and obligations shall be exercised and performed by
such co-trustee or separate trustee.

     (c)  The Property Trustee at any time, by an instrument in writing executed
by it, with the written concurrence of the Depositor, may accept the resignation
of or remove any co-trustee or separate trustee appointed under this Section,
and, in case a Indenture Event of Default has occurred and is continuing, the
Property Trustee shall have power to accept the resignation of, or remove, any
such co-trustee or separate trustee without the concurrence of the Depositor.
Upon the written request of the Property Trustee, the Depositor shall join with
the Property Trustee in the execution, delivery and performance of all
instruments and agreements necessary or proper to effectuate such resignation or
removal. A successor to any co-trustee or separate trustee so resigned or
removed may be appointed in the manner provided in this Section.

     (d)  No co-trustee or separate trustee hereunder shall be personally liable
by reason of any act or omission of the Property Trustee or any other trustee
hereunder.

     (e)  The Property Trustee shall not be liable by reason of any act of a co-
trustee or separate trustee.

     (f)  Any Act of Holders delivered to the Property Trustee shall be deemed
to have been delivered to each such co-trustee and separate trustee.

     SECTION 8.10.  Resignation and Removal; Appointment of Successor.

     No resignation or removal of any Trustee (the "Relevant Trustee") and no
appointment of a successor Trustee pursuant to this Article shall become
effective until the acceptance of appointment by the successor Trustee in
accordance with the applicable requirements of Section 8.11.

     Subject to the immediately preceding paragraph, the Relevant Trustee may
resign at any time by giving written notice thereof to the Securityholders.  If
the instrument of acceptance by the successor Trustee required by Section 8.11
shall not have been delivered to the Relevant Trustee within 30 days after the
giving of such notice of resignation, the Relevant Trustee may petition, at the
expense of the Trust, any court of competent jurisdiction for the appointment of
a successor Relevant Trustee.

     Unless a Indenture Event of Default shall have occurred and be continuing,
any Trustee may be removed at any time by Act of the Common Securityholder.  If
a Indenture Event of Default shall

                                       38
<PAGE>

have occurred and be continuing, the Property Trustee or the Delaware Trustee,
or both of them, may be removed at such time by Act of the Holders of a majority
in Liquidation Amount of the Preferred Securities, delivered to the Relevant
Trustee (in its individual capacity and on behalf of the Trust). An
Administrative Trustee(s) may be removed by the Common Securityholder at any
time.

     If any Trustee shall resign, be removed or become incapable of acting as
Trustee, or if a vacancy shall occur in the office of any Trustee for any cause,
at a time when no Indenture Event of Default shall have occurred and be
continuing, the Common Securityholder, by Act of the Common Securityholder
delivered to the retiring Trustee, shall promptly appoint a successor Trustee or
Trustees, which successor Trustee shall be domiciled outside of the State of
Oklahoma, and the retiring Trustee shall comply with the applicable requirements
of Section 8.11.  If the Property Trustee or the Delaware Trustee shall resign,
be removed or become incapable of continuing to act as the Property Trustee or
the Delaware Trustee, as the case may be, at a time when a Indenture Event of
Default shall have occurred and be continuing, the Preferred Securityholders, by
Act of the Securityholders of a majority in Liquidation Amount of the Preferred
Securities then Outstanding delivered to the retiring Relevant Trustee, shall
promptly appoint a successor Relevant Trustee or Trustees, and such successor
Trustee shall comply with the applicable requirements of Section 8.11. If an
Administrative Trustee shall resign, be removed or become incapable of acting as
Administrative Trustee, at a time when a Indenture Event of Default shall have
occurred and be continuing, the Common Securityholder by Act of the Common
Securityholder delivered to the Administrative Trustee(s) shall promptly appoint
a successor Administrative Trustee or Administrative Trustee(s) and such
successor Administrative Trustee or Trustees shall comply with the applicable
requirements of Section 8.11.  If no successor Relevant Trustee shall have been
so appointed by the Common Securityholder or the Preferred Securityholders and
accepted appointment in the manner required by Section 8.11, any Securityholder
who has been a Securityholder of Trust Securities for at least six months may,
on behalf of himself and all others similarly situated, petition any court of
competent jurisdiction for the appointment of a successor Relevant Trustee.

     The Property Trustee shall give notice of each resignation and each removal
of a Trustee and each appointment of a successor Trustee to all Securityholders
in the manner provided in Section 10.8 and shall give notice to the Depositor.
Each notice shall include the name of the successor Relevant Trustee and the
address of its Corporate Trust Office if it is the Property Trustee.

     Notwithstanding the foregoing or any other provision of this Trust
Agreement, in the event any Administrative Trustee or a Delaware Trustee who is
a natural person dies or becomes, in the opinion of the Depositor, incompetent
or incapacitated, the vacancy created by such death, incompetence or incapacity
may be filled by (a) the unanimous act of the remaining Administrative
Trustee(s) if there are at least two of them or (b) otherwise by the Depositor
(with the successor in each case being a Person who satisfies the eligibility
requirement for Administrative Trustee(s) or Delaware Trustee, as the case may
be, set forth in Section 8.7).

     SECTION 8.11.  Acceptance of Appointment by Successor.

     In case of the appointment hereunder of a successor Trustee such successor
Trustee so appointed shall execute, acknowledge and deliver to the Trust and to
the retiring Trustee an instrument accepting such appointment, and thereupon the
resignation or removal of the retiring

                                       39
<PAGE>

Trustee shall become effective and such successor Trustee, without any further
act, deed or conveyance, shall become vested with all the rights, powers, trusts
and duties of the retiring Trustee; but, on the request of the Depositor or the
successor Trustee, such retiring Trustee shall, upon payment of its charges,
execute and deliver an instrument transferring to such successor Trustee all the
rights, powers and trusts of the retiring Trustee and if the Property Trustee is
the resigning Trustee shall duly assign, transfer and deliver to the successor
Trustee all property and money held by such retiring Property Trustee hereunder.

     In case of the appointment hereunder of a successor Relevant Trustee, the
retiring Relevant Trustee and each successor Relevant Trustee with respect to
the Trust Securities shall execute and deliver an amendment hereto wherein each
successor Relevant Trustee shall accept such appointment and which (a) shall
contain such provisions as shall be necessary or desirable to transfer and
confirm to, and to vest in, each successor Relevant Trustee all the rights,
powers, trusts and duties of the retiring Relevant Trustee with respect to the
Trust Securities and the Trust and (b) shall add to or change any of the
provisions of this Trust Agreement as shall be necessary to provide for or
facilitate the administration of the Trust by more than one Relevant Trustee, it
being understood that nothing herein or in such amendment shall constitute such
Relevant Trustees co-trustees and upon the execution and delivery of such
amendment the resignation or removal of the retiring Relevant Trustee shall
become effective to the extent provided therein and each such successor Relevant
Trustee, without any further act, deed or conveyance, shall become vested with
all the rights, powers, trusts and duties of the retiring Relevant Trustee; but,
on request of the Trust or any successor Relevant Trustee such retiring Relevant
Trustee shall duly assign, transfer and deliver to such successor Relevant
Trustee all Trust Property, all proceeds thereof and money held by such retiring
Relevant Trustee hereunder with respect to the Trust Securities and the Trust.

     Upon request of any such successor Relevant Trustee, the Trust shall
execute any and all instruments for more fully and certainly vesting in and
confirming to such successor Relevant Trustee all such rights, powers and trusts
referred to in the first or second preceding paragraph, as the case may be.

     No successor Relevant Trustee shall accept its appointment unless at the
time of such acceptance such successor Relevant Trustee shall be qualified and
eligible under this Article.

     SECTION 8.12.  Merger, Conversion, Consolidation or Succession to Business.

     Any corporation into which the Property Trustee or the Delaware Trustee may
be merged or converted or with which it may be consolidated, or any corporation
resulting from any merger, conversion or consolidation to which such Relevant
Trustee shall be a party, or any corporation succeeding to all or substantially
all the corporate trust business of such Relevant Trustee, shall be the
successor of such Relevant Trustee hereunder, provided such corporation shall be
otherwise qualified and eligible under this Article, without the execution or
filing of any paper or any further act on the part of any of the parties hereto.

     SECTION 8.13.  Preferential Collection of Claims Against Depositor or
                    Trust.

                                       40
<PAGE>

     In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
similar judicial proceeding relative to the Trust or any other obligor upon the
Trust Securities or the property of the Trust or of such other obligor or their
creditors, the Property Trustee (irrespective of whether any Distributions on
the Trust Securities shall then be due and payable as therein expressed or by
declaration or otherwise and irrespective of whether the Property Trustee shall
have made any demand on the Trust for the payment of any past due Distributions)
shall be entitled and empowered, to the fullest extent permitted by law, by
intervention in such proceeding or otherwise:

     (a)  to file and prove a claim for the whole amount of any Distributions
owing and unpaid in respect of the Trust Securities and to file such other
papers or documents as may be necessary or advisable in order to have the claims
of the Property Trustee (including any claim for the reasonable compensation,
expenses, disbursements and advances of the Property Trustee, its agents and
counsel) and of the Holders allowed in such judicial proceeding, and

     (b)  to collect and receive any moneys or other property payable or
deliverable on any such claims and to distribute the same;

and any custodian, receiver, assignee, trustee, liquidator, sequestrator or
other similar official in any such judicial proceeding is hereby authorized by
each Holder to make such payments to the Property Trustee and, in the event the
Property Trustee shall consent to the making of such payments directly to the
Holders, to pay to the Property Trustee any amount due it for the reasonable
compensation, expenses, disbursements and advances of the Property Trustee, its
agents and counsel, and any other amounts due the Property Trustee.

     Nothing herein contained shall be deemed to authorize the Property Trustee
to authorize or consent to or accept or adopt on behalf of any Holder any plan
of reorganization, arrangement adjustment or compensation affecting the Trust
Securities or the rights of any Holder thereof or to authorize the Property
Trustee to vote in respect of the claim of any Holder in any such proceeding.

     SECTION 8.14.  Reports by Property Trustee.

     (a)  Not later than 60 days following May 15 of each year commencing with
May 15, 2000, the Property Trustee shall transmit to all Securityholders in
accordance with Section 10.8, and to the Depositor, a brief report dated as of
such May 15 with respect to:

          (i)       its eligibility under Section 8.7 or, in lieu thereof, if to
     the best of its knowledge it has continued to be eligible under said
     Section, a written statement to such effect;

          (ii)      a statement that the Property Trustee has complied with all
     of its obligations under this Trust Agreement during the twelve-month
     period (or, in the case of the initial report, the period since the Closing
     Date) ending with such May 15 or, if the Property Trustee has not complied
     in any material respect with such obligations, a description of such
     noncompliance; and

                                       41
<PAGE>

          (iii)     any change in the property and funds in its possession as
     Property Trustee since the date of its last report and any action taken by
     the Property Trustee in the performance of its duties hereunder which it
     has not previously reported and which in its opinion materially affects the
     Trust Securities.

     (b)  In addition the Property Trustee shall transmit to Securityholders
such reports concerning the Property Trustee and its actions under this Trust
Agreement as may be required pursuant to the Trust Indenture Act at the times
and in the manner provided pursuant thereto.

     (c)  A copy of each such report shall, at the time of such transmission to
Holders, be filed by the Property Trustee with each national stock exchange, the
NASDAQ National Market or such other interdealer quotation system or self-
regulatory organization upon which the Trust Securities are listed or traded,
with the Commission and with the Depositor.

     SECTION 8.15.  Reports to the Property Trustee.

     The Depositor and the Administrative Trustee(s) on behalf of the Trust
shall provide to the Property Trustee such documents, reports and information as
required by Section 314 of the Trust Indenture Act (if any) and the compliance
certificate required by Section 314(a) of the Trust Indenture Act in the form,
in the manner and at the times required by Section 314 of the Trust Indenture
Act.

     SECTION 8.16.  Evidence of Compliance with Conditions Precedent.

     Each of the Depositor and the Administrative Trustee(s) on behalf of the
Trust shall provide to the Property Trustee such evidence of compliance with any
conditions precedent, if any, provided for in this Trust Agreement that relate
to any of the matters set forth in Section 314 (c) of the Trust Indenture Act.
Any certificate or opinion required to be given by an officer pursuant to
Section 314(c)(1) of the Trust Indenture Act shall be given in the form of an
Officer's Certificate.

     SECTION 8.17.  Number of Trustees.

     (a)  The number of Trustees shall initially be three, provided that the
Holder of all of the Common Securities by written instrument may increase or
decrease the number of Administrative Trustee(s). The Property Trustee and the
Delaware Trustee may be the same Person.

     (b)  If a Trustee ceases to hold office for any reason and the number of
Administrative Trustee(s) is not reduced pursuant to Section 8.17(a), or if the
number of Trustees is increased pursuant to Section 8.17(a), a vacancy shall
occur. The vacancy shall be filled with a Trustee appointed in accordance with
Section 8.10.

     (c)  The death, resignation, retirement, removal, bankruptcy, incompetence
or incapacity to perform the duties of a Trustee shall not operate to annul the
Trust. Whenever a vacancy in the number of Administrative Trustee(s) shall
occur, until such vacancy is filled by the appointment of an Administrative
Trustee(s) in accordance with Section 8.10, the Administrative Trustee(s) in
office, regardless of their number (and notwithstanding any other provision of
this Agreement), shall have

                                       42
<PAGE>

all the powers granted to the Administrative Trustee(s) and shall discharge all
the duties imposed upon the Administrative Trustee(s) by this Trust Agreement.

     SECTION 8.18.  Delegation of Power.

     (a)  Any Administrative Trustee may, by power of attorney consistent with
applicable law, delegate to any other natural person over the age of 21 his or
her power for the purpose of executing any documents contemplated in Section
2.7(a), including any registration statement or amendment thereto filed with the
Commission, or making any other governmental filing; and

     (b)  The Administrative Trustee(s) shall have power to delegate from time
to time to such of their number or to the Depositor the doing of such things and
the execution of such instruments either in the name of the Trust or the names
of the Administrative Trustee(s) or otherwise as the Administrative Trustee(s)
may deem expedient, to the extent such delegation is not prohibited by
applicable law or contrary to the provisions of this Trust Agreement, as set
forth herein.


                                  ARTICLE IX.

                      TERMINATION, LIQUIDATION AND MERGER

     SECTION 9.1.   Termination Upon Expiration Date.

     Unless earlier terminated, the Trust shall automatically terminate on
December 31, 2040 (the "Expiration Date"), following the distribution of the
Trust Property in accordance with Section 9.4.

     SECTION 9.2.   Early Termination.

     The first to occur of any of the following events is an "Early Termination
Event":

     (a)  the occurrence of a Bankruptcy Event in respect of, or the dissolution
or liquidation of, the Depositor;

     (b)  the written direction to the Property Trustee from the Depositor at
any time to terminate the Trust and distribute Notes to Securityholders in
exchange for the Preferred Securities (which direction is optional and wholly
within the discretion of the Depositor);

     (c)  the redemption of all of the Preferred Securities in connection with
the redemption of all the Notes; and

     (d)  the entry of an order for dissolution of the Trust by a court of
competent jurisdiction.

     SECTION 9.3.   Termination.

     The respective obligations and responsibilities of the Trustees and the
Trust created and continued hereby shall terminate upon the latest to occur of
the following:  (a) the distribution by the

                                       43
<PAGE>

Property Trustee to Securityholders upon the liquidation of the Trust pursuant
to Section 9.4, or upon the redemption of all of the Trust Securities pursuant
to Section 4.2, of all amounts required to be distributed hereunder upon the
final payment of the Trust Securities; (b) the payment of any expenses owed by
the Trust; and (c) the discharge of all administrative duties of the
Administrative Trustee(s), including the performance of any tax reporting
obligations with respect to the Trust or the Securityholders.

     SECTION 9.4.   Liquidation.

     (a)  If an Early Termination Event specified in clause (a), (b) or (d) of
Section 9.2 occurs or upon the Expiration Date, the Trust shall be liquidated by
the Trustees as expeditiously as the Trustees determine to be possible by
distributing, after satisfaction of liabilities to creditors of the Trust as
provided by applicable law, to each Securityholder a Like Amount of Notes,
subject to Section 9.4(d). Notice of liquidation shall be given by the Property
Trustee by first-class mail, postage prepaid mailed not later than 30 nor more
than 60 days prior to the Liquidation Date to each Holder of Trust Securities at
such Holder's address appearing in the Securities Register. All notices of
liquidation shall:

          (i)       state the Liquidation Date;

          (ii)      state that from and after the Liquidation Date, the Trust
     Securities will no longer be deemed to be Outstanding and any Trust
     Securities Certificates not surrendered for exchange will be deemed to
     represent a Like Amount of Notes; and

          (iii)     provide such information with respect to the mechanics by
     which Holders may exchange Trust Securities Certificates for Notes, or if
     Section 9.4(d) applies receive a Liquidation Distribution, as the
     Administrative Trustee(s) or the Property Trustee shall deem appropriate.

     (b)  Except where Section 9.2(c) or 9.4(d) applies, in order to effect the
liquidation of the Trust and distribution of the Notes to Securityholders, the
Property Trustee shall establish a record date for such distribution (which
shall be not more than 45 days prior to the Liquidation Date) and, either itself
acting as exchange agent or through the appointment of a separate exchange
agent, shall establish such procedures as it shall deem appropriate to effect
the distribution of Notes in exchange for the Outstanding Trust Securities
Certificates.

     (c)  Except where Section 9.2(c) or 9.4(d) applies, after the Liquidation
Date, (i) the Trust Securities will no longer be deemed to be Outstanding, (ii)
certificates representing a Like Amount of Notes will be issued to holders of
Trust Securities Certificates, upon surrender of such certificates to the
Administrative Trustee(s) or their agent for exchange, (iii) the Depositor shall
use its best efforts to have the Notes listed on the New York Stock Exchange or
on such other exchange, interdealer quotation system or self-regulatory
organization as the Preferred Securities are then listed, (iv) any Trust
Securities Certificates not so surrendered for exchange will be deemed to
represent a Like Amount of Notes, accruing interest at the rate provided for in
the Notes from the last Distribution Date on which a Distribution was made on
such Trust Securities Certificates until such certificates are so surrendered
(and until such certificates are so surrendered, no payments of interest

                                       44
<PAGE>

or principal will be made to Holders of Trust Securities Certificates with
respect to such Notes) and (v) all rights of Securityholders holding Trust
Securities will cease, except the right of such Securityholders to receive Notes
upon surrender of Trust Securities Certificates.

     (d)  In the event that, notwithstanding the other provisions of this
Section 9.4, whether because of an order for dissolution entered by a court of
competent jurisdiction or otherwise, distribution of the Notes in the manner
provided herein is determined by the Property Trustee not to be practical, the
Trust Property shall be liquidated, and the Trust shall be dissolved, wound-up
or terminated, by the Property Trustee in such manner as the Property Trustee
determines. In such event, on the date of the dissolution, winding-up or other
termination of the Trust, Securityholders will be entitled to receive out of the
assets of the Trust available for distribution to Securityholders, after
satisfaction of liabilities to creditors of the Trust as provided by applicable
law, an amount equal to the Liquidation Amount per Trust Security plus
accumulated and unpaid Distributions thereon to the date of payment (such amount
being the "Liquidation Distribution"). If, upon any such dissolution, winding up
or termination, the Liquidation Distribution can be paid only in part because
the Trust has insufficient assets available to pay in full the aggregate
Liquidation Distribution, then, subject to the next succeeding sentence, the
amounts payable by the Trust on the Trust Securities shall be paid on a pro rata
basis (based upon Liquidation Amounts). The holder of the Common Securities will
be entitled to receive Liquidation Distributions upon any such dissolution,
winding-up or termination pro rata (determined as aforesaid) with Holders of
Preferred Securities, except that, if a Indenture Event of Default has occurred
and is continuing, the Preferred Securities shall have a priority over the
Common Securities.

     SECTION 9.5.   Mergers, Consolidations, Amalgamations or Replacements of
the Trust.

     The Trust may not merge with or into, consolidate, amalgamate, or be
replaced by, or convey, transfer or lease its properties and assets
substantially as an entirety to any corporation or other body, except pursuant
to this Section 9.5. At the request of the Depositor, with the consent of the
Guarantor and the Administrative Trustee(s) and without the consent of the
Holders of the Preferred Securities, the Property Trustee or the Delaware
Trustee, the Trust may merge with or into, consolidate, amalgamate, or be
replaced by or convey, transfer or lease its properties and assets substantially
as an entirety to a trust organized as such under the laws of any State;
provided, that (i) such successor entity either (a) expressly assumes all of the
obligations of the Trust with respect to the Preferred Securities or (b)
substitutes for the Preferred Securities other securities having substantially
the same terms as the Preferred Securities (the "Successor Securities") so long
as the Successor Securities rank the same as the Preferred Securities rank in
priority with respect to distributions and payments upon liquidation, redemption
and otherwise, (ii) the Depositor expressly appoints a trustee of such successor
entity possessing the same powers and duties as the Property Trustee as the
holder of the Notes, (iii) the Successor Securities are listed or traded, or any
Successor Securities will be listed upon notification of issuance, on any
national securities exchange or other organization on which the Preferred
Securities are then listed or traded, if any, (iv) such merger, consolidation,
amalgamation, replacement, conveyance, transfer or lease does not cause the
Preferred Securities (including any Successor Securities) to be downgraded by
any nationally recognized statistical rating organization, (v) such merger,
consolidation, amalgamation, replacement, conveyance, transfer or lease does not
adversely affect the rights, preferences and privileges of the holders of the
Preferred Securities (including any Successor Securities) in any material
respect, (vi)

                                       45
<PAGE>

such successor entity has a purpose identical to that of the Trust, (vii) prior
to such merger, consolidation, amalgamation, replacement, conveyance, transfer
or lease, the Depositor has received an Opinion of Counsel to the effect that
(a) such merger, consolidation, amalgamation, replacement, conveyance, transfer
or lease does not adversely affect the rights, preferences and privileges of the
holders of the Preferred Securities (including any Successor Securities) in any
material respect, and (b) following such merger, consolidation, amalgamation,
replacement, conveyance, transfer or lease, neither the Trust nor such successor
entity will be required to register as an investment company under the 1940 Act
and (viii) the Depositor owns all of the Common Securities of such successor
entity and the Guarantor guarantees the obligations of such successor entity
under the Successor Securities at least to the extent provided by the Guarantee.
Notwithstanding the foregoing, the Trust shall not, except with the consent of
holders of 100% in Liquidation Amount of the Preferred Securities, consolidate,
amalgamate, merge with or into, or be replaced by or convey, transfer or lease
its properties and assets substantially as an entirety to any other entity or
permit any other entity to consolidate, amalgamate, merge with or into, or
replace it if such consolidation, amalgamation, merger, replacement, conveyance,
transfer or lease would cause the Trust or the successor entity to be classified
as other than a grantor trust for United States Federal income tax purposes.

                                  ARTICLE X.

                           MISCELLANEOUS PROVISIONS

     SECTION 10.1.  Limitation of Rights of Securityholders.

     The death or incapacity of any person having an interest, beneficial or
otherwise, in Trust Securities shall not operate to terminate this Trust
Agreement, nor entitle the legal representatives or heirs of such person or any
Securityholder for such person, to claim an accounting, take any action or bring
arty proceeding in any court for a partition or winding up of the arrangements
contemplated hereby, nor otherwise affect the rights, obligations and
liabilities of the parties hereto or any of them.

     SECTION 10.2.  Amendment.

     (a)  This Trust Agreement may be amended from time to time by the Property
Trustee, the Administrative Trustee(s) and the Depositor, without the consent of
any Securityholders, (i) to cure any ambiguity, correct or supplement any
provision herein which may be inconsistent with any other provision herein, or
to make any other provisions with respect to matters or questions arising under
this Trust Agreement, which shall not be inconsistent with the other provisions
of this Trust Agreement, or (ii) to modify, eliminate or add to any provisions
of this Trust Agreement to such extent as shall be necessary to ensure that the
Trust will be classified for United States Federal income tax purposes as a
grantor trust at all times that any Trust Securities are outstanding or to
ensure that the Trust will not be required to register as an investment company
under the 1940 Act; provided, however, that in the case of clause (i), such
action shall not adversely affect in any material respect the interests of any
Securityholder, and any amendments of this Trust Agreement shall become
effective when notice thereof is given to the Securityholders.

     (b)  Except as provided in Section 10.2(c) hereof, any provision of this
Trust Agreement may be amended by the Trustees and the Depositor with (i) the
consent of Trust Securityholders

                                       46
<PAGE>

representing a majority (based upon Liquidation Amounts) of the Trust Securities
then Outstanding and (ii) receipt by the Trustees of an Opinion of Counsel to
the effect that such amendment or the exercise of any power granted to the
Trustees in accordance with such amendment will not affect the Trust's status as
a grantor trust for United States Federal income tax purposes or the Trust's
exemption from status of an investment company under the 1940 Act.

     (c)  In addition to and notwithstanding any other provision in this Trust
Agreement, without the consent of each affected Securityholder (such consent
being obtained in accordance with Section 6.3 or 6.6 hereof), this Trust
Agreement may not be amended to (i) change the amount or timing of any
Distribution on the Trust Securities or otherwise adversely affect the amount of
any Distribution required to be made in respect of the Trust Securities as of a
specified date or (ii) restrict the right of a Securityholder to institute suit
for the enforcement of any such payment on or after such date; notwithstanding
any other provision herein, without the unanimous consent of the Securityholders
(such consent being obtained in accordance with Section 6.3 or 6.6 hereof), this
paragraph (c) of this Section 10.2 may not be amended.

     (d)  Notwithstanding any other provisions of this Trust Agreement, no
Trustee shall enter into or consent to any amendment to this Trust Agreement
which would cause the Trust to fail or cease to qualify for the exemption from
status of an investment company under the 1940 Act or fail or cease to be
classified as a grantor trust for United States Federal income tax purposes.

     (e)  Notwithstanding anything in this Trust Agreement to the contrary, this
Trust Agreement may not be amended in a manner which imposes any additional
obligation on the Depositor, the Property Trustee or the Delaware Trustee
without the consent of the Depositor, the Property Trustee or the Delaware
Trustee, as the case may be.

     (f)  In the event that any amendment to this Trust Agreement is made, the
Administrative Trustee(s) shall promptly provide to the Depositor a copy of such
amendment.

     (g)  Neither the Property Trustee nor the Delaware Trustee shall be
required to enter into any amendment to this Trust Agreement which affects its
own rights, duties or immunities under this Trust Agreement. The Property
Trustee shall be entitled to receive an Opinion of Counsel and an Officer's
Certificate stating that any amendment to this Trust Agreement is in compliance
with this Trust Agreement.

     SECTION 10.3.  Separability.

     In case any provision in this Trust Agreement or in the Trust Securities
Certificates shall be invalid, illegal or unenforceable, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby.

     SECTION 10.4.  Governing Law.

     THIS TRUST AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF EACH OF THE
SECURITYHOLDERS, THE TRUST AND THE TRUSTEES WITH RESPECT TO THIS TRUST AGREEMENT
AND THE TRUST SECURITIES SHALL BE CONSTRUED

                                       47
<PAGE>

IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF DELAWARE WITHOUT
REGARD TO THE CONFLICT OF LAWS PRINCIPLES THEREOF.

     SECTION 10.5.  Payments Due on Non-Business Day.

     If the date fixed for any payment on any Trust Security shall be a day that
is not a Business Day, then such payment need not be made on such date but may
be made on the next succeeding day that is a Business Day (except as otherwise
provided in Sections 4.1(a) and 4.2(d)), with the same force and effect as
though made on the date fixed for such payment, and no interest shall accrue
thereon for the period after such date.

     SECTION 10.6.  Successors.

     This Trust Agreement shall be binding upon and shall inure to the benefit
of any successor to the Depositor, the Trust or the Relevant Trustee, including
any successor by operation of law. Except in connection with a consolidation,
merger or sale involving the Depositor that is permitted under Article Eight of
the Indenture and pursuant to which the assignee agrees in writing to perform
the Depositor's obligations hereunder, the Depositor shall not assign its
obligations hereunder.

     SECTION 10.7.  Headings.

     The Article and Section headings are for convenience only and shall not
affect the construction of this Trust Agreement.

     SECTION 10.8.  Reports, Notices and Demands.

     Any report, notice, demand or other communication which by any provision of
this Trust Agreement is required or permitted to be given or served to or upon
any Securityholder or the Depositor may be given or served in writing by deposit
thereof, first-class postage prepaid, in the United States mail, hand delivery
or facsimile transmission, in each case, addressed, (a) in the case of a
Preferred Securityholder, to such Preferred Securityholder as such
Securityholder's name and address may appear on the Securities Register; and (b)
in the case of the Common Securityholder or the Depositor, to ONEOK, Inc.,
[____________], Wilmington, Delaware 19801, Attention: Treasurer.  Any notice to
Preferred Securityholders shall also be given to such owners as have, within two
years preceding the giving of such notice, filed their names and addresses with
the Property Trustee for that purpose. Such notice, demand or other
communication to or upon a Securityholder shall be deemed to have been
sufficiently given or made, for all purposes, upon hand delivery, mailing or
transmission.

Any notice, demand or other communication which by any provision of this Trust
Agreement is required or permitted to be given or served to or upon the Trust,
the Property Trustee, the Delaware Trustee or the Administrative Trustee(s)
shall be given in writing addressed (until another address is published by the
Trust) as follows: (a) with respect to the Property Trustee to [____________],
[____________], Attention: [____________]; (b) with respect to the Delaware
Trustee, to [____________], [____________], Attention: [____________] and (c)
with respect to the

                                       48
<PAGE>

Administrative Trustee(s), to them c/o [__________________________________],
marked "Attention Administrative Trustee(s) of ONEOK Capital Trust I." Such
notice, demand or other communication to or upon the Trust or the Property
Trustee shall be deemed to have been sufficiently given or made only upon actual
receipt of the writing by the Trust or the Property Trustee.

     Section 10.9  Agreement Not to Petition.

     Each of the Trustees and the Depositor agree for the benefit of the
Securityholders that, until at least one year and one day after the Trust has
been terminated in accordance with Article IX, they shall not file, or join in
the filing of, a petition against the Trust under any bankruptcy, insolvency,
reorganization or other similar law (including, without limitation, the United
States Bankruptcy Code) (collectively, "Bankruptcy Laws") or otherwise join in
the commencement of any proceeding against the Trust under any Bankruptcy Law.
In the event the Depositor takes action in violation of this Section 10.9, the
Property Trustee agrees, for the benefit of Securityholders, that at the expense
of the Depositor, it shall file an answer with the bankruptcy court or otherwise
properly contest the filing of such petition by the Depositor against the Trust
or the commencement of such action and raise the defense that the Depositor has
agreed in writing not to take such action and should be stopped and precluded
therefrom and such other defenses, if any, as counsel for the Trustee or the
Trust may assert.  The provisions of this Section 10.9 shall survive the
termination of this Trust Agreement.

     Section 10.10 Trust Indenture Act; Conflict with Trust Indenture Act.

     (a) This Trust Agreement is subject to the provisions of the Trust
Indenture Act that are required to be part of this Trust Agreement and shall, to
the extent applicable, be governed by such provisions.

     (b) The Property Trustee shall be the only Trustee which is a trustee for
the purposes of the Trust Indenture Act.

     (c) If any provision hereof limits, qualifies or conflicts with another
provision hereof which is required to be included in this Trust Agreement by any
of the provisions of the Trust Indenture Act, such required provision shall
control.  If any provision of this Trust Agreement modifies or excludes any
provision of the Trust Indenture Act which may be so modified or excluded, the
latter provision shall be deemed to apply to this Trust Agreement as so modified
or excluded, as the case may be.

     (d) The application of the Trust Indenture Act to this Trust Agreement
shall not affect the nature of the Securities as equity securities representing
undivided beneficial interests in the assets of the Trust.

     Section 10.11 Acceptance of Terms of Trust Agreement, Guarantee and
Indenture.

     THE RECEIPT AND ACCEPTANCE OF A TRUST SECURITY OR ANY INTEREST THEREIN BY
OR ON BEHALF OF A SECURITYHOLDER OR ANY BENEFICIAL OWNER, WITHOUT ANY SIGNATURE
OR FURTHER MANIFESTATION OF ASSENT, SHALL CONSTITUTE THE UNCONDITIONAL
ACCEPTANCE BY THE SECURITYHOLDER AND

                                       49
<PAGE>

ALL OTHERS HAVING A BENEFICIAL INTEREST IN SUCH TRUST SECURITY OF ALL THE TERMS
AND PROVISIONS OF THIS TRUST AGREEMENT AND AGREEMENT TO THE SUBORDINATION
PROVISIONS AND OTHER TERMS OF THE GUARANTEE AND THE INDENTURE, AND SHALL
CONSTITUTE THE AGREEMENT OF THE TRUST, SUCH SECURITYHOLDER AND SUCH OTHERS THAT
THE TERMS AND PROVISIONS OF THIS TRUST AGREEMENT SHALL BE BINDING, OPERATIVE AND
EFFECTIVE AS BETWEEN THE TRUST AND SUCH SECURITYHOLDER AND SUCH OTHERS.

                                             ONEOK, INC.


                                             By:_________________________
                                                Name:____________________
                                                Title:___________________

                                             Executed in [_________]


                                             [_______________________],
                                                as Property Trustee

                                             By:_________________________
                                                Name:____________________
                                                Title:___________________

                                             Executed in [_________].


                                             [________________],
                                              as Delaware Trustee

                                             By:_________________________
                                                Name:____________________
                                                Title:___________________

                                             Executed In [_________].

                                             [_________________________],
                                              as Administrative Trustee

                                             By:_________________________
                                                Name:____________________
                                                Title:___________________

                                             Executed in [_________].

                                       50
<PAGE>

                                                                       EXHIBIT A

                             CERTIFICATE OF TRUST

                                      OF

                             ONEOK CAPITAL TRUST I

     THIS Certificate of Trust of ONEOK CAPITAL TRUST I (the "Trust") is being
duly executed and filed on behalf of the Trust by the undersigned, as trustees,
to form a business trust under the Delaware Business Trust Act (12 Del. C. ((S))
3801 et seq.) (the "Act").

     1.  Name.  The name of the business trust formed hereby is ONEOK CAPITAL
         ----
TRUST I.

     2.  Delaware Trustee.  The name and business address of the trustee of the
         ----------------
Trust in the State of Delaware is [____________], [____________], [__________],
Delaware [______].

     3.  Effective Date.  This Certificate of Trust shall be effective upon
         --------------
filing with the Secretary of State.

     IN WITNESS WHEREOF, the undersigned have duly executed this Certificate of
Trust in accordance with Section 3811 (a)(1) of the Act.

                                             [_____________________],
                                               as trustee

                                             By:_________________________



                                             [_____________________],
                                               as trustee

                                             By:_________________________

<PAGE>

                                                                       EXHIBIT B


The Depository Trust Company,
55 Water Street, 49th Floor,
New York, New York 10041-0099                                 ____________, 1999

Attention:  General Counsel's Office

Re: ONEOK Capital Trust I [____]% Preferred Trust Securities.

Ladies and Gentlemen:

     The purpose of this letter is to set forth certain matters relating to the
issuance and deposit with The Depository Trust Company ("DTC") of the ONEOK
Capital Trust I [____]% Preferred Trust Securities, (the "Preferred
Securities"), of ONEOK Capital Trust I, a Delaware business trust (the
"Issuer"), formed pursuant to a Trust Agreement between ONEOK, Inc. and
[__________] as Property Trustee, [__________], as Delaware Trustee, and the
Administrative Trustee named therein. The payment of distributions on the
Preferred Securities, and payments due upon liquidation of Issuer or redemption
of the Preferred Securities, to the extent the Issuer has funds available for
the payment thereof are guaranteed by ONEOK Inc. to the extent set forth in a
Guarantee Agreement dated [______ __], 1999 by ONEOK, Inc. with respect to the
Preferred Securities. ONEOK Inc. and the Issuer propose to sell the Preferred
Securities to certain Underwriters (the "Underwriters") pursuant to an
Underwriting Agreement dated [_____ __], 1999 by and among the Underwriters, the
Issuer and ONEOK Inc. and the Underwriters wish to take delivery of the
Preferred Securities through DTC. [____________] is acting as transfer agent and
registrar with respect to the Preferred Securities (the "Transfer Agent and
Registrar").

     To induce DTC to accept the Preferred Securities as eligible for deposit at
DTC, and to act in accordance with DTC's rules with respect to the Preferred
Securities, the Issuer, the Transfer Agent and Registrar and DTC agree among
each other as follows:

     1.   Prior to the closing of the sale of the Preferred Securities to the
Underwriters, which is expected to occur on or about [______  __], 1999, there
shall be deposited with DTC one or more global certificates (individually and
collectively, the "Global Certificate") registered in the name of DTC's'S
Preferred Securities nominee, Cede & Co., representing an aggregate of
[____________] Preferred Securities and bearing the following legend:

     Unless this certificate is presented by an authorized representative of The
     Depository Trust Company, a New York corporation ("DTC"), to Issuer or its
     agent for registration of transfer, exchange, or payment, and any
     certificate issued is registered in the name of Cede & Co. or in such other
     name as is requested by an authorized representative of DTC (and any
     payment is made to Cede & Co. or to such other entity as is requested by an
     authorized representative of DTC), ANY TRANSFER, PLEDGE, OR OTHER USE
     HEREOF FOR VALUE OR

                                       1
<PAGE>

     OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
     hereof, Cede & Co., has an interest herein.

     2.   The Amended and Restated Trust Agreement of the Issuer provides for
the voting by holders of the Preferred Securities under certain limited
circumstances.  The Issuer shall establish a record date for such purposes and
shall, to the extent possible, give DTC notice of such record date not less than
15 calendar days in advance of such record date.

     3.   In the event of a stock split, conversion, recapitalization,
reorganization or any other similar transaction resulting in the cancellation of
all or any part of the Preferred Securities outstanding, the Issuer or the
Transfer Agent and Registrar shall send DTC a notice of such event at least 5
business days prior to the effective date of such event.

     4.   In the event of distribution on, or an offering or issuance of rights
with respect to, the Preferred Securities outstanding, the Issuer or the
Transfer Agent and Registrar shall send DTC a notice specifying: (a) the amount
of and conditions, if any, applicable to the payment of any such distribution or
any such offering or issuance of rights; (b) any applicable expiration or
deadline date, or any date by which any action on the part of the holders of
Preferred Securities is required; and (c) the date any required notice is to be
mailed by or on behalf of the Issuer to holders of Preferred Securities or
published by or on behalf of the Issuer (whether by mail or publication, the
"Publication Date").  Such notice shall be sent to DTC by a secure means (e.g.,
legible telecopy, registered or certified mail, overnight delivery) in a timely
manner designed to assure that such notice is in DTC's possession no later than
the close of business on the business day before the Publication Date.  The
Issuer or the Transfer Agent and Registrar will forward such notice either in a
separate secure transmission for each CUSIP number or in a secure transmission
of multiple CUSIP numbers (if applicable) that includes a manifest or list of
each CUSIP number submitted in that transmission. (The party sending such notice
shall have a method to verify subsequently the use of such means and the
timeliness of such notice.) The Publication Date shall be not less than 30
calendar days nor more than 60 calendar days prior to the payment of any such
distribution or any such offering or issuance of rights with respect to the
Preferred Securities.  After establishing the amount of payment to be made on
the Preferred Securities, the Issuer or the Transfer Agent and Registrar will
notify DTC's Dividend Department of such payment 5 business days prior to
payment date.  Notices to DTC's Dividend Department by telecopy shall be sent to
(212) 709-1723.  Such notices by mail or by any other means shall be sent to:

     Manager, Announcements
     Dividend Department
     The Depository Trust Company
     7 Hanover Square, 23rd Floor
     New York, New York 10004-2695

     The Issuer or the Transfer Agent and Registrar shall confirm DTC's receipt
of such telecopy by telephoning the Dividend Department at (212) 709-1270.

     5.   In the event of a redemption by the Issuer of the Preferred
Securities, notice specifying the terms of the redemption and the Publication
Date of such notice shall be sent by the Issuer or the

                                       2
<PAGE>

Transfer Agent and Registrar to DTC not less than 30 calendar days prior to such
event by a secure means in the manner set forth in paragraph 4. Such redemption
notice shall be sent to DTC's Call Notification Department at (516) 227-4164 or
(516) 227-4190, and receipt of such notice shall be confirmed by telephoning
(516) 227-4070. Notice by mail or by any other means shall be sent to:

     Call Notification Department
     The Depository Trust Company
     711 Stewart Avenue
     Garden City, New York 11530-4719

     6.   In the event of any invitation to tender the Preferred Securities,
notice specifying the terms of the tender and the Publication Date of such
notice shall be sent by the Issuer or the Transfer Agent and Registrar to DTC by
a secure means and in a timely manner as described in paragraph 4. Notices to
DTC pursuant to this paragraph and notices of other corporate actions (including
mandatory tenders, exchanges and capital changes) shall be sent, unless
notification to another department is expressly provided for herein, by telecopy
to DTC's Reorganization Department at (212) 709-1093 or (212) 709-1094 and
receipt of such notice shall be confirmed by telephoning (212) 709-6884, or by
mail or any other means to:

     Manager, Reorganization Department
     Reorganization Window
     The Depository Trust Company
     7 Hanover Square, 23rd Floor
     New York, New York 10004-2695

     7.   All notices and payment advices sent to DTC shall contain the CUSIP
number or numbers of the Preferred Securities and the accompanying designation
of the Preferred Securities, which, as of the date of this letter, is "ONEOK
Capital Trust I [______]% Preferred Trust Securities.

     8.   Distribution payments or other cash payments with respect to the
Preferred Securities evidenced by the Global Certificate shall be received by
Cede & Co., as nominee of DTC, or its registered assigns in next day funds on
each payment date (or in accordance with existing arrangements between the
Issuer or the Transfer Agent and Registrar and DTC).  Such payments shall be
made payable to the order of Cede & Co., and shall be addressed as follows:

     NDFS Redemption Department
     The Depository Trust Company
     7 Hanover Square, 23rd Floor
     New York, New York 10004-2695

     9.   DTC may by prior written notice direct the Issuer and the Transfer
Agent and Registrar to use any other telecopy number or address of DTC as the
number or address to which notices or payments may be sent.

     10.  In the event of a conversion, redemption, or any other similar
transaction (e.g., tender made and accepted in response to the Issuer's or the
Transfer Agent and Registrar's invitation)

                                       3
<PAGE>

necessitating a reduction in the aggregate number of Preferred Securities
outstanding evidenced by Global Certificates, DTC, in its discretion: (a) may
request the Issuer or the Transfer Agent and Registrar to issue and countersign
a new Global Certificate; or (b) may make an appropriate notation on the Global
Certificate indicating the date and amount of such reduction.

     11.  DTC may discontinue its services as a securities depository with
respect to the Preferred Securities at any time by giving at least 90 days'
prior written notice to the Issuer and the Transfer Agent and Registrar (at
which time DTC will confirm with the Issuer or the Transfer Agent and Registrar
the aggregate number of Preferred Securities deposited with it) and discharging
its responsibilities with respect thereto under applicable law.  Under such
circumstances, the Issuer may determine to make alternative arrangements for
book-entry settlement for the Preferred Securities, make available one or more
separate global certificates evidencing Preferred Securities to any Participant
having Preferred Securities credited to its DTC account, or issue definitive
Preferred Securities to the beneficial holders thereof, and in any such case,
DTC agrees to cooperate fully with the Issuer and the Transfer Agent and
Registrar, and to return the Global Certificate, duly endorsed for transfer as
directed by the Issuer or the Transfer Agent and Registrar, together with any
other documents of transfer reasonably requested by the Issuer or the Transfer
Agent and Registrar.

     12.  In the event that the Issuer determines that beneficial owners of
Preferred Securities shall be able to obtain definitive Preferred Securities,
the Issuer or the Transfer Agent and Registrar shall notify DTC'S of the
availability of certificates.  In such event, the Issuer or the Transfer Agent
and Registrar shall issue, transfer and exchange certificates in appropriate
amounts, as required by DTC'S and others, and DTC'S agrees to cooperate fully
with the Issuer and the Transfer Agent and Registrar and to return the Global
Certificate, duly endorsed for transfer as directed by the Issuer or the
Transfer Agent and Registrar, together with any other documents of transfer
reasonably requested by the Issuer or the Transfer Agent and Registrar.

     13.  This letter may be executed in any number of counterparts, each of
which when so executed shall be deemed to be an original, but all such
counterparts shall together constitute but one and the same instrument.

     Nothing herein shall be deemed to require the Transfer Agent and Registrar
to advance funds on behalf of ONEOK Capital Trust I.

                                        Very truly yours,

                                        ONEOK Capital Trust I
                                           (as Issuer)
                                        By:  ONEOK, Inc., as Depositor


                                        By:_____________________________
                                           Name:________________________
                                           Title:_______________________

                                        (As Transfer Agent and Registrar)

                                       4
<PAGE>

                                        [_________________],
                                          as Trustee

                                        By:___________________________
                                           Name:______________________
                                           Title:_____________________

Received and Accepted:

The Depository Trust Company

By:__________________________
     Authorized Officer

                                       5
<PAGE>

                                                                       EXHIBIT C

                     THIS CERTIFICATE IS NOT TRANSFERABLE
                    EXCEPT IN CERTAIN LIMITED CIRCUMSTANCES
             SET FORTH IN THE AMENDED AND RESTATED TRUST AGREEMENT
                           OF ONEOK CAPITAL TRUST I

Certificate Number                     Number of Common Securities
     C-1                                      [____________]

                    Certificate Evidencing Common Securities
                                       of
                             Oneok Capital Trust I

                          [______]% Common Securities
                  (liquidation amount $25 per Common Security)

     ONEOK Capital Trust I, a statutory business trust formed under the laws of
the State of Delaware (the ""Trust"), hereby certifies that ONEOK, Inc. (the
"Holder") is the registered owner of [______________________] common securities
of the Trust representing beneficial interests of the Trust and designated the
[____]% Common Securities (liquidation amount $25 per Common Security) (the
"Common Securities"). In accordance with Section 5.10 of the Trust Agreement (as
defined below) the Common Securities are not transferable and any attempted
transfer hereof shall be void. The designations, rights, privileges,
restrictions, preferences and other terms and provisions of the Common
Securities are set forth in, and this certificate and the Common Securities
represented hereby are issued and shall in all respects be subject to the terms
and provisions of, the Amended and Restated Trust Agreement of the Trust dated
as of [_______ __],1999, as the same may be amended from time to time (the
"Trust Agreement") including the designation of the terms of the Common
Securities as set forth therein. The Trust will furnish a copy of the Trust
Agreement to the Holder without charge upon written request to the Trust at its
principal place of business or registered office.

     Upon receipt of this certificate, the Holder is bound by the Trust
Agreement and is entitled to the benefits thereunder.

     In Witness Whereof, the Administrative Trustee of the Trust has executed
this certificate in the City of _______________, State of _____________ this
______ day of ____________, 1999.

                                    ONEOK CAPITAL TRUST I

                                    [_______________], As Administrative Trustee

                                    By:_____________________________________
                                       Name:________________________________
                                       Title:_______________________________

                                       1
<PAGE>

                                                                       EXHIBIT D

                    AGREEMENT AS TO EXPENSES AND LIABILITIES

     Agreement dated as of [______  __], 1999, between ONEOK Inc., an Oklahoma
corporation, and ONEOK Capital Trust I, a Delaware business trust (the "Trust").

     Whereas, the Trust intends to issue its Common Securities (the "Common
Securities") to and receive Notes from ONEOK Inc., an Oklahoma corporation, and
to issue and sell [______]%, Preferred Trust Securities (the "Preferred
Securities") with such powers, preferences and special rights and restrictions
as are set forth in the Amended and Restated Trust Agreement of the Trust dated
as of [_______  __], 1999 as the same may be amended from time to time (the
"Trust Agreement");

     Whereas, ONEOK, Inc. will directly or indirectly own all of the Common
Securities of the Trust and will issue the Notes;

     Whereas, ONEOK Inc. is the guarantor of the Notes.

     Now, Therefore, in consideration of the purchase by each holder of the
Preferred Securities, which purchase ONEOK Inc. hereby agrees shall benefit
ONEOK Inc. and which purchase ONEOK Inc. acknowledges will be made in reliance
upon the execution and delivery of this Agreement, ONEOK Inc. and the Trust
hereby agree as follows:


                                   ARTICLE I

     Section 1.1.  Guarantee by ONEOK Inc.

     Subject to the terms and conditions hereof, ONEOK Inc. hereby irrevocably
and unconditionally guarantees to each person or entity to whom the Trust is now
or hereafter becomes indebted or liable (the "Beneficiaries") the full payment,
when and as due, of any and all Obligations (as hereinafter defined) to such
Beneficiaries, As used herein, "Obligations" means any costs, expenses or
liabilities of the Trust, other than obligations of the Trust to pay to holders
of any Preferred Securities or other similar interests in the Trust the amounts
due such holders pursuant to the terms of the Preferred Securities or such other
similar interests, as the case may be. This Agreement is intended to be for the
benefit of, and to be enforceable by, all such Beneficiaries, whether or not
such Beneficiaries have received notice hereof.

     Section 1.2.  Term of Agreement.

     This Agreement shall terminate and be of no further force and effect upon
the later of (a) the date on which full payment has been made of all amounts
payable to all holders of all the Preferred Securities (whether upon redemption,
liquidation, exchange or otherwise) and (b) the date on which there are no
Beneficiaries remaining; provided, however, that this Agreement shall continue
to be effective or shall be reinstated, as the case may be, if at any time any
holder of Preferred Securities

                                       2
<PAGE>

or any Beneficiary must restore payment of any sums paid under the Preferred
Securities, under any Obligation, under the Guarantee Agreement dated the date
hereof by ONEOK Inc. and [_______________], as guarantee trustee or under this
Agreement for any reason whatsoever, This Agreement is continuing, irrevocable,
unconditional and absolute.

     Section 1.3.  Waiver of Notice.

     ONEOK Inc. hereby waives notice of acceptance of this Agreement and of any
Obligation to which it applies or may apply, and ONEOK Inc. hereby waives
presentment, demand for payment, protest, notice of nonpayment, notice of
dishonor, notice of redemption and all other notices and demands.

     Section 1.4.  No Impairment.

     The obligations, covenants, agreements and duties of ONEOK Inc. under this
Agreement shall in no way be affected or impaired by reason of the happening
from time to time of any of the following:

     (a) the extension of time for the payment by the Trust of all or any
portion of the Obligations or for the performance of any other obligation under,
arising out of, or in connection with, the obligations;

     (b) any failure, omission, delay or lack of diligence on the part of the
Beneficiaries to enforce, assert or exercise any right, privilege, power or
remedy conferred on the Beneficiaries with respect to the Obligations or any
action on the part of the Trust granting indulgence or extension of any kind; or

     (c) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement, composition or readjustment of debt of,
or other similar proceedings affecting, the Trust or any of the assets of the
Trust.

There shall be no obligation of the Beneficiaries to give notice to, or obtain
the consent of, ONEOK Inc. with respect to the happening of any of the
foregoing.

     Section 1.5.  Enforcement.

     A Beneficiary may enforce this Agreement directly against ONEOK Inc. and
ONEOK Inc. waives any right or remedy to require that any action be brought
against the Trust or any other person or entity before proceeding against ONEOK
Inc..

     Section 1.6.  Subrogation.

     ONEOK Inc. shall be subrogated to all (if any) rights of the Trust in
respect of any amounts paid to the Beneficiaries by ONEOK Inc. under this
Agreement; provided, however, that ONEOK Inc. shall not (except to the extent
required by mandatory provisions of law) be entitled to enforce

                                       3
<PAGE>

or exercise any rights which it may acquire by way of subrogation or any
indemnity, reimbursement or other agreement, in all cases as a result of payment
under this Agreement, if, at the time of any such payment, any amounts are due
and unpaid under this Agreement.


                                   ARTICLE II

     Section 2.1.  Binding Effect.

     All guarantees and agreements contained in this Agreement shall bind the
successors, assigns, receivers, trustees and representatives of ONEOK Inc. and
shall inure to the benefit of the Beneficiaries.

     Section 2.2.  Amendment.

     So long as there remains any Beneficiary or any Preferred Securities of any
series are outstanding, this Agreement shall not be modified or amended in any
manner adverse to such Beneficiary or to the holders of the Preferred
Securities.

     Section 2.3.  Notices.

     Any notice, request or other communication required or permitted to be
given hereunder shall be given in writing by delivering the same against receipt
therefor by facsimile transmission (confirmed by mail), telex or by registered
or certified mail, addressed as follows (and if so given, shall be deemed given
when mailed or upon receipt of an answer-back, if sent by telex):

     ONEOK Capital Trust I
     ____________________
     ____________________
     Attention: ____________________

     ONEOK Inc.
     100 West Fifth Street
     Tulsa, Oklahoma  74103
     Facsimile No.: (918) 588-7960
     Attention: Treasurer

     Section 2.4.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND
INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD
TO THE CONFLICT OF LAW PRINCIPLES THEREOF.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       4
<PAGE>

     This Agreement is executed as of the day and year first above written and
at the location indicated below.

                                     ONEOK Inc.


                                     By:_________________________________
                                        Name:____________________________
                                        Title:___________________________

                                     Executed in_________________________


                                     ONEOK CAPITAL TRUST I

                                           [________________________________],
                                           as Administrative Trustee


                                           By:_________________________________
                                              Name:____________________________
                                              Title:___________________________

                                    Executed in [_______________]

                                       5
<PAGE>

                                                                       EXHIBIT E

     [IF THE PREFERRED SECURITY IS TO BE A GLOBAL CERTIFICATE INSERT-- This
Preferred Security is a Global Certificate within the meaning of the Trust
Agreement hereinafter referred to and is registered in the name of The
Depository Trust Company (the "Depository") or a nominee of the Depository.
This Preferred Security is exchangeable for Preferred Securities registered in
the name of a person other than the Depository or its nominee only in the
limited circumstances described in the Trust Agreement and no transfer of this
Preferred Security (other than a transfer of this Preferred Security as a whole
by the Depository to a nominee of the Depository or by a nominee of the
Depository to the Depository or another nominee of the Depository) may be
registered except in limited circumstances.

     Unless this Preferred Security is presented by an authorized representative
of The Depository Trust Company (55 Water Street, New York) to ONEOK Capital
Trust I or its agent for registration of transfer, exchange or payment, and any
Preferred Security issued is registered in the name of Cede & Co.  or such other
name as requested by an authorized representative of The Depository Trust
Company and any payment hereon is made to Cede & Co., ANY TRANSFER, PLEDGE OR
OTHER USE HEREOF FOR VALUE OR OTHERWISE BY A PERSON IS WRONGFUL inasmuch as the
registered owner hereof, Cede & Co., has an interest herein.]

Certificate Number                       Number of Preferred Securities
     P
                                    CUSIP NO. [_______________]

                  Certificate Evidencing Preferred Securities

                                       Of

                             Oneok Capital Trust I

                       [____]% Preferred Trust Securities
                (liquidation amount $25 per Preferred Security)

     ONEOK Capital Trust I, a statutory business trust formed under the laws of
the State of Delaware (the "Trust"), hereby certifies that ____________ (the
"Holder") is the registered owner of the number set forth above of preferred
securities of the Trust representing an undivided beneficial interest in the
assets of the Trust and designated the ONEOK Capital Trust I [____]% Preferred
Trust Securities (liquidation amount $25 per Preferred Security) (the "Preferred
Securities").  The Preferred Securities are transferable on the books and
records of the Trust, in person or by a duly authorized attorney, upon surrender
of this certificate duly endorsed and in proper form for transfer as provided in
Section 5.4 of the Trust Agreement (as defined below).  The designations,
rights, privileges, restrictions, preferences and other terms and provisions of
the Preferred Securities are set forth in, and this certificate and the
Preferred Securities represented hereby are issued and shall in all respects be
subject to the terms and provisions of, the Amended and Restated Trust Agreement
of the Trust dated as of [_______  __], 1999, as the same may be amended from
time to time (the "Trust Agreement") including the designation of the terms of
Preferred Securities as set forth therein.  The

                                       1
<PAGE>

Holder is entitled to the benefits of the Guarantee Agreement entered into by
ONEOK Inc., an Oklahoma corporation, and [_______________], as guarantee
trustee, dated as of [______ __], 1999, (the "Guarantee"), to the extent
provided therein. The Trust will furnish a copy of the Trust Agreement and the
Guarantee to the Holder without charge upon written request to the Trust at its
principal place of business or registered office.

     Upon receipt of this certificate, the Holder is bound by the Trust
Agreement and is entitled to the benefits thereunder.

     IN WITNESS WHEREOF, the Administrative Trustee of the Trust has executed
this certificate in the City of ________________, State of ________________ this
_____ day of _____________,1999.

                                     ONEOK CAPITAL TRUST I


                                     [____________________],
                                     as Administrative Trustee


                                     By:_________________________________
                                     Name:_______________________________
                                     Title:______________________________

                                       2
<PAGE>

                                   ASSIGNMENT

     for Value Received, the undersigned assigns and transfers this Preferred
Security to:
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
        (Insert assignee's social security or tax identification number)

_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
                   (Insert address and zip code of assignee)

and irrevocably appoints
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________

agent to transfer this Preferred Security Certificate on the books of the Trust.
The agent may substitute another to act for him or her.

Date:_______________

Signature:

_______________________________________________________________________________
(Sign exactly as your name appears on the other side of this Preferred Security
Certificate)

The signature(s) should be guaranteed by an eligible guarantor institution
(banks, stockbrokers, savings and loan associations and credit unions with
membership in an approved signature guarantee medallion program), pursuant to
S.E.C. Rule l7Ad-15.

                                       3

<PAGE>

                                                                     EXHIBIT 4.8


                              GUARANTEE AGREEMENT



                                    Between



                                  ONEOK, INC.
                                (as Guarantor)



                                      and



                         _____________________________
                                 (as Trustee)



                                  dated as of



                            ________________, 1999
<PAGE>

                            CROSS-REFERENCE TABLE*


        Section of
   Trust Indenture Act                                       Section of
   of 1939, as amended                                   Guarantee Agreement
   -------------------                                   -------------------

         310(a).                                             4.1(a)
         310(b).                                             4.1(c), 2.8
         310(c).                                             Inapplicable
         311(a).                                             2.2(b)
         311(b).                                             2.2(b)
         311(c).                                             Inapplicable
         312(a).                                             2.2(a)
         312(b).                                             2.2(b)
         313.                                                2.3
         314(a).                                             2.4
         314(b).                                             Inapplicable
         314(c).                                             2.5
         314(d).                                             Inapplicable
         314(e).                                             1.1, 2.5, 3.2
         314(f).                                             2.1, 3.2
         315(a).                                             3.1(d)
         315(b).                                             2.7
         315(c).                                             3.1
         315(d).                                             3.1(d)
         316(a).                                             1.1, 2.6, 5.4
         316(b).                                             5.3
         316(c).                                             8.2
         317(a).                                             Inapplicable
         317(b).                                             Inapplicable
         318(a).                                             2.1(b)
         318(b).                                             2.1
         318(c).                                             2.1(a)

- ------------
*        This Cross-Reference Table does not constitute part of the Guarantee
         Agreement and shall not affect the interpretation of any of its terms
         or provisions.
<PAGE>

                               TABLE OF CONTENTS

                                                                          Page

ARTICLE I.   DEFINITIONS................................................     1
     Section 1.1. Definitions...........................................     1

ARTICLE II.  TRUST INDENTURE ACT........................................     4
     Section 2.1. Trust Indenture Act; Application......................     4
     Section 2.2. List of Holders.......................................     4
     Section 2.3. Reports by the Guarantee Trustee......................     4
     Section 2.4. Periodic Reports to the Guarantee Trustee.............     4
     Section 2.5. Evidence of Compliance with Conditions Precedent......     5
     Section 2.6. Events of Default; Waiver.............................     5
     Section 2.7. Event of Default; Notice..............................     5
     Section 2.8. Conflicting Interests.................................     6

ARTICLE III. POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE.........     6
     Section 3.1. Powers and Duties of the Guarantee Trustee............     6
     Section 3.2. Certain Rights of Guarantee Trustee...................     7
     Section 3.3. Indemnity.............................................     9

ARTICLE IV.  GUARANTEE TRUSTEE..........................................     9
     Section 4.1. Guarantee Trustee: Eligibility........................     9
     Section 4.2. Appointment, Removal and Resignation of the Guarantee
                  Trustee...............................................    10

ARTICLE V.   GUARANTEE..................................................    10
     Section 5.1. Guarantee.............................................    10
     Section 5.2. Waiver of Notice and Demand...........................    10
     Section 5.3. Obligations Not Affected..............................    11
     Section 5.4. Rights of Holders.....................................    12
     Section 5.5. Guarantee of Payment..................................    12
     Section 5.6. Subrogation...........................................    12
     Section 5.7. Independent Obligations...............................    12

ARTICLE VI.  COVENANTS AND SUBORDINATION................................    13
     Section 6.1. Subordination.........................................    13
     Section 6.2. Pari Passu Guarantees.................................    13

ARTICLE VII. TERMINATION................................................    13


                                      ii
<PAGE>

     Section 7.1. Termination........................................... 13

ARTICLE VIII. MISCELLANEOUS............................................. 13
     Section 8.1. Successors and Assigns................................ 13
     Section 8.2. Amendments............................................ 14
     Section 8.3. Notices............................................... 14
     Section 8.4. Benefit............................................... 15
     Section 8.5. Interpretation........................................ 15
     Section 8.6. Governing Law......................................... 16


                                      iii
<PAGE>

                              GUARANTEE AGREEMENT


     This GUARANTEE AGREEMENT, dated as of ________, 1999 is executed and
delivered by ONEOK, INC., an Oklahoma corporation ("ONEOK") having its principal
office at 100 West Fifth Street, Tulsa, Oklahoma 74103, and
_______________________________, a national banking association duly organized
and existing under the laws of the United States, as trustee (the "Guarantee
Trustee"), for the benefit of the Holders (as defined herein) from time to time
of the Preferred Securities (as defined herein) of ONEOK Capital Trust I, a
Delaware statutory business trust (the "Issuer").

     WHEREAS, pursuant to an Amended and Restated Trust Agreement dated as of
__________, 1999 (the "Trust Agreement") among ONEOK, as Depositor, the Property
Trustee, the Administrative Trustee and the Delaware Trustee named therein and
the Holders from time to time of undivided beneficial interests in the assets of
the Issuer, the Issuer is issuing $_________ aggregate Liquidation Amount (as
defined in the Trust Agreement) of its ____% [Trust Preferred Securities]
(Liquidation Amount $[25] per Preferred Security) (the "Preferred Securities"),
representing preferred undivided beneficial interests in the assets of the
Issuer and having the terms set forth in the Trust Agreement;

     WHEREAS, the Preferred Securities will be issued by the Issuer and the
proceeds thereof, together with the  proceeds from the issuance of the Issuer's
Common Securities (as defined below), will be used to purchase the Notes (as
defined in the Trust Agreement) of ONEOK which will be deposited with
_______________________, as Property Trustee under the Trust Agreement, as trust
assets; and

     WHEREAS, as incentive for the Holders to purchase Preferred Securities
ONEOK desires irrevocably and unconditionally to agree, to the extent set forth
herein, to pay to the Holders of the Preferred Securities the Guarantee Payments
(as defined herein) and to make certain other payments on the terms and
conditions set forth herein.

     NOW, THEREFORE, in consideration of the purchase by each Holder of
Preferred Securities, which purchase ONEOK hereby agrees shall benefit ONEOK,
ONEOK executes and delivers this Guarantee Agreement for the benefit of the
Holders from time to time of the Preferred Securities.

                           ARTICLE I.   DEFINITIONS
<PAGE>

     SECTION 1.1.   Definitions.

     As used in this Guarantee Agreement, the terms set forth below shall,
unless the context otherwise requires, have the following meanings. Capitalized
or otherwise defined terms used but not otherwise defined herein shall have the
meanings assigned to such terms in the Trust Agreement as in effect on the date
hereof.

     "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person; provided, however, that an Affiliate of
ONEOK shall not be deemed to be an Affiliate of the Issuer. For the purposes of
this definition, "control" when used with respect to any specified Person means
the power to direct the management and policies of such Person, directly or
indirectly, whether through the ownership of voting securities, by contract or
otherwise; and the terms "controlling" and "controlled" have meanings
correlative to the foregoing.

     "Board of Directors" means either the board of directors of ONEOK or the
Guarantee Trustee, as the case may be, or any committee of that board duly
authorized to act hereunder.

     "Common Securities" means the securities representing common undivided
beneficial interests in the assets of the Issuer.

     "Event of Default" means a default by ONEOK on any of its payment or other
obligations under this Guarantee Agreement; provided, however, that, except with
respect to a default in payment of any Guarantee Payments, ONEOK shall have
received notice of default and shall not have cured such default within 60 days
after receipt of such notice.

     "Guarantee Payments" means the following payments or distributions, without
duplication, with respect to the Preferred Securities, to the extent not paid or
made by or on behalf of the Issuer: (i) any accrued and unpaid Distributions (as
defined in the Trust Agreement) required to be paid on the Preferred Securities,
to the extent the Issuer shall have funds on hand available therefor at such
time, (ii) the redemption price, including all accrued and unpaid Distributions
to the date of redemption (the "Redemption Price"), with respect to any
Preferred Securities called for redemption by the Issuer, to the extent the
Issuer shall have funds on hand available therefor at such time, and (iii) upon
a voluntary or involuntary termination, winding-up or liquidation of the Issuer,
unless Notes are distributed to the Holders, the lesser of (a) the aggregate of
the Liquidation Amount of $[25] per Preferred Security plus accrued and unpaid
Distributions on the Preferred Securities to the date of payment, to the extent
the Issuer shall have funds on hand available therefor at such time and (b) the
amount of assets of the Issuer remaining available for distribution to Holders
in liquidation of the Issuer (in either case, the "Liquidation Distribution").

     "Guarantee Trustee" means ___________________, until a Successor Guarantee
Trustee has been appointed and has accepted such appointment pursuant to the
terms of this Guarantee Agreement, and thereafter means each such Successor
Guarantee Trustee.

     "Holder" means any holder, as registered on the books and records of the
Issuer, of any Preferred Securities; provided, however, that in determining
whether the holders of the requisite


                                       2
<PAGE>

percentage of Preferred Securities have given any request, notice, consent or
waiver hereunder, "Holder" shall not include ONEOK, the Guarantee Trustee, or
any Affiliate of ONEOK or the Guarantee Trustee.

     "Indenture" means the Junior Subordinated Indenture dated as of __________,
1999, as supplemented and amended, between ONEOK and ________________________,
as trustee.

     "List of Holders" has the meaning specified in Section 2.2(a).

     "Majority in Liquidation Amount of the Securities" means, except as
provided by the Trust Indenture Act, a vote by the Holder(s), voting separately
as a class, of more than 50% of the Liquidation Amount of all then outstanding
Preferred Securities issued by the Issuer.

     "Officers' Certificate" means, with respect to any Person, a certificate
signed by the Chairman or a Vice Chairman of the Board of Directors of such
Person or the President or a Vice President of such Person, and by the
Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary of
such Person, and delivered to the Guarantee Trustee. Any Officers' Certificate
delivered with respect to compliance with a condition or covenant provided for
in this Guarantee Agreement shall include:

     (a) a statement that each officer signing the Officers' Certificate has
read the covenant or condition and the definitions relating thereto;

     (b) a brief statement of the nature and scope of the examination or
investigation undertaken by each officer in rendering the Officers' Certificate;

     (c) a statement that each officer has made such examination or
investigation as, in such officer's opinion, is necessary to enable such officer
to express an informed opinion as to whether or not such covenant or condition
has been complied with; and

     (d) a statement as to whether, in the opinion of each officer, such
condition or covenant has been complied with.

     "Person" means a legal person, including any individual, corporation,
estate, partnership, joint venture, association, joint stock company, limited
liability company, trust, unincorporated association, or government or any
agency or political subdivision thereof, or any other entity of whatever nature.

     "Responsible Officer" means, with respect to the Guarantee Trustee, any
Senior Vice President, any Vice President, any Assistant Vice President, the
Secretary, any Assistant Secretary, the Treasurer, any Assistant Treasurer, any
Trust Officer or Assistant Trust Officer or any other officer of the Corporate
Trust Department of the Guarantee Trustee and also means, with respect to a
particular corporate trust matter, any other officer to whom such matter is
referred because of that officer's knowledge of and familiarity with the
particular subject.

     "Successor Guarantee Trustee" means a successor Guarantee Trustee
possessing the qualifications to act as Guarantee Trustee under Section 4.1.



                                       3
<PAGE>

     "Trust Indenture Act" means the Trust Indenture Act of 1939, as amended.


                       ARTICLE II.   TRUST INDENTURE ACT

     SECTION 2.1.   Trust Indenture Act; Application.

     (a) This Guarantee Agreement is subject to the provisions of the Trust
Indenture Act that are required to be part of this Guarantee Agreement and
shall, to the extent applicable, be governed by such provisions.

     (b) If and to the extent that any provision of this Guarantee Agreement
limits, qualifies or conflicts with the duties imposed by Sections 310 to 317,
inclusive, of the Trust Indenture Act, such imposed duties shall control.

     SECTION 2.2.   List of Holders.

     (a) ONEOK shall furnish or cause to be furnished to the Guarantee Trustee
(a) semiannually, on or before January 15 and July 15 of each year, a list, in
such form as the Guarantee Trustee may reasonably require, of the names and
addresses of the Holders ("List of Holders") as of a date not more than 15 days
prior to the delivery thereof, and (b) at such other times as the Guarantee
Trustee may request in writing, within 30 days after the receipt by ONEOK of any
such request, a List of Holders as of a date not more than 15 days prior to the
time such list is furnished, in each case to the extent such information is in
the possession or control of ONEOK and is not identical to a previously supplied
list of Holders or has not otherwise been received by the Guarantee Trustee in
its capacity as such. The Guarantee Trustee may destroy any List of Holders
previously given to it on receipt of a new List of Holders.

     (b) The Guarantee Trustee shall comply with its obligations under Section
311(a), Section 311(b) and Section 312(b) of the Trust Indenture Act.

     SECTION 2.3.   Reports by the Guarantee Trustee.

     Not later than 60 days following May 15 of each year, commencing May 15,
2000, the Guarantee Trustee shall provide to the Holders such reports as are
required by Section 313 of the Trust Indenture Act, if any, in the form and in
the manner provided by Section 313 of the Trust Indenture Act. The Guarantee
Trustee shall also comply with the requirements of Section 313(d) of the Trust
Indenture Act.

     SECTION 2.4.   Periodic Reports to the Guarantee Trustee.

     ONEOK shall provide to the Guarantee Trustee, the Securities and Exchange
Commission and the Holders such documents, reports and information, if any, as
required by Section 314 of the Trust Indenture Act and the compliance
certificate required by Section 314 of the Trust Indenture Act, in the form, in
the manner and at the times required by Section 314 of the Trust Indenture Act.



                                       4
<PAGE>

     SECTION 2.5.   Evidence of Compliance with Conditions Precedent.

     ONEOK shall provide to the Guarantee Trustee such evidence of compliance
with such conditions precedent, if any, provided for in this Guarantee Agreement
that relate to any of the matters set forth in Section 314(c) of the Trust
Indenture Act. Any certificate or opinion required to be given by an officer
pursuant to Section 314(c)(1) may be given in the form of an Officers'
Certificate.

     SECTION 2.6.   Events of Default; Waiver.

     The Holders of a Majority in Liquidation Amount of the Preferred Securities
may, by vote, on behalf of the Holders, waive any past Event of Default and its
consequences. Upon such waiver, any such Event of Default shall cease to exist,
and any Event of Default arising therefrom shall be deemed to have been cured,
for every purpose of this Guarantee Agreement, but no such waiver shall extend
to any subsequent or other default or Event of Default or impair any right
consequent therefrom.

     SECTION 2.7.   Event of Default; Notice.

     (a) The Guarantee Trustee shall, within 90 days after the occurrence of an
Event of Default actually known to the Guarantee Trustee, transmit by mail,
first class postage prepaid, to the Holders, notices of all such Events of
Default, unless such defaults have been cured or waived before the giving of
such notice, provided, that, except in the case of a default in the payment of a
Guarantee Payment, the Guarantee Trustee shall be protected in withholding such
notice if and so long as the Board of Directors, the executive committee or a
trust committee of directors and/or Responsible Officers of the Guarantee
Trustee in good faith determines that the withholding of such notice is in the
interests of the Holders.

     (b) The Guarantee Trustee shall not be deemed to have knowledge of any
Event of Default unless the Guarantee Trustee shall have received written
notice, or a Responsible Officer charged with the administration of this
Guarantee Agreement shall have obtained written notice, of such Event of
Default.

     SECTION 2.8.   Conflicting Interests.

     The Trust Agreement and the Indenture shall be deemed to be specifically
described in this Guarantee Agreement for the purposes of clause (i) of the
first proviso contained in Section 310(b) of the Trust Indenture Act.


ARTICLE III.  POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

     SECTION 3.1.   Powers and Duties of the Guarantee Trustee.

     (a) This Guarantee Agreement shall be held by the Guarantee Trustee for the
benefit of the Holders, and the Guarantee Trustee shall not transfer this
Guarantee Agreement to any Person except a Holder exercising his or her rights
pursuant to Section 5.4(iv) or to a Successor Guarantee Trustee



                                       5
<PAGE>

on acceptance by such Successor Guarantee Trustee of its appointment to act as
Successor Guarantee Trustee. The right, title and interest of the Guarantee
Trustee shall automatically vest in any Successor Guarantee Trustee, upon
acceptance by such Successor Guarantee Trustee of its appointment hereunder, and
such vesting and cessation of title shall be effective whether or not
conveyancing documents have been executed and delivered pursuant to the
appointment of such Successor Guarantee Trustee.

     (b) If an Event of Default has occurred and is continuing, the Guarantee
Trustee shall enforce this Guarantee Agreement for the benefit of the Holders.

     (c) The Guarantee Trustee, before the occurrence of any Event of Default
and after the curing or waiving of all Events of Default that may have occurred,
shall undertake to perform only such duties as are specifically set forth in
this Guarantee Agreement, and no implied covenants shall be read into this
Guarantee Agreement against the Guarantee Trustee. In case an Event of Default
has occurred (that has not been cured or waived pursuant to Section 2.6), the
Guarantee Trustee shall exercise such of the rights and powers vested in it by
this Guarantee Agreement, and use the same degree of care and skill in its
exercise thereof, as a prudent person would exercise or use under the
circumstances in the conduct of his or her own affairs.

     (d) No provision of this Guarantee Agreement shall be construed to relieve
the Guarantee Trustee from liability for its own negligent action, its own
negligent failure to act or its own willful misconduct, except that:

          (i) prior to the occurrence of any Event of Default and after the
     curing or waiving of all such Events of Default that may have occurred:

               (A) the duties and obligations of the Guarantee Trustee shall be
          determined solely by the express provisions of this Guarantee
          Agreement, and the Guarantee Trustee shall not be liable except for
          the performance of such duties and obligations as are specifically set
          forth in this Guarantee Agreement; and

               (B) in the absence of bad faith on the part of the Guarantee
          Trustee, the Guarantee Trustee may conclusively rely, as to the truth
          of the statements and the correctness of the opinions expressed
          therein, upon any certificates or opinions furnished to the Guarantee
          Trustee and conforming to the requirements of this Guarantee
          Agreement; but in the case of any such certificates or opinions that
          by any provision hereof or of the Trust Indenture Act are specifically
          required to be furnished to the Guarantee Trustee, the Guarantee
          Trustee shall be under a duty to examine the same to determine whether
          or not they conform to the requirements of this Guarantee Agreement;

          (ii) the Guarantee Trustee shall not be liable for any error of
     judgment made in good faith by a Responsible Officer of the Guarantee
     Trustee, unless it shall be proved that the Guarantee Trustee was negligent
     in ascertaining the pertinent facts upon which such judgment was made;



                                       6
<PAGE>

          (iii) the Guarantee Trustee shall not be liable with respect to any
     action taken or omitted to be taken by it in good faith in accordance with
     the direction of the Holders of not less than a Majority in Liquidation
     Preference of the Preferred Securities relating to the time, method and
     place of conducting any proceeding for any remedy available to the
     Guarantee Trustee, or exercising any trust or power conferred upon the
     Guarantee Trustee under this Guarantee Agreement; and

          (iv)  no provision of this Guarantee Agreement shall require the
     Guarantee Trustee to expend or risk its own funds or otherwise incur
     personal financial liability in the performance of any of its duties or in
     the exercise of any of its rights or powers, if the Guarantee Trustee shall
     have reasonable grounds for believing that the repayment of such funds or
     liability is not reasonably assured to it under the terms of this Guarantee
     Agreement or adequate indemnity against such risk or liability is not
     reasonably assured to it.

      Section 3.2.   Certain Rights of Guarantee Trustee.

      (a) Subject to the provisions of Section 3.1:

          (i)   The Guarantee Trustee may rely and shall be fully protected in
     acting or refraining from acting upon any resolution, certificate,
     statement, instrument, opinion, report, notice, request, direction,
     consent, order, bond, debenture, note, other evidence of indebtedness or
     other paper or document reasonably believed by it to be genuine and to have
     been signed, sent or presented by the proper party or parties.

          (ii)  Any direction or act of the Guarantor contemplated by this
     Guarantee Agreement shall be sufficiently evidenced by an Officers'
     Certificate unless otherwise prescribed herein.

          (iii) Whenever, in the administration of this Guarantee Agreement,
     the Guarantee Trustee shall deem it desirable that a matter be proved or
     established before taking, suffering or omitting to take any action
     hereunder, the Guarantee Trustee (unless other evidence is herein
     specifically prescribed) may, in the absence of bad faith on its part,
     request and rely upon an Officers' Certificate which, upon receipt of such
     request from the Guarantee Trustee, shall be promptly delivered by ONEOK.

          (iv)  The Guarantee Trustee may consult with legal counsel, and the
     written advice or opinion of such legal counsel with respect to legal
     matters shall be full and complete authorization and protection in respect
     of any action taken, suffered or omitted to be taken by it hereunder in
     good faith and in accordance with such advice or opinion. Such legal
     counsel may be legal counsel to ONEOK or any of its Affiliates and may be
     one of its employees. The Guarantee Trustee shall have the right at any
     time to seek instructions concerning the administration of this Guarantee
     Agreement from any court of competent jurisdiction.

          (v)   The Guarantee Trustee shall be under no obligation to exercise
     any of the rights or powers vested in it by this Guarantee Agreement at the
     request or direction of any Holder, unless such Holder shall have provided
     to the Guarantee Trustee such adequate security and indemnity as would
     satisfy a reasonable person in the position of the Guarantee Trustee,

                                      11
<PAGE>

     against the costs, expenses (including attorneys' fees and expenses) and
     liabilities that might be incurred by it in complying with such request or
     direction, including such reasonable advances as may be requested by the
     Guarantee Trustee; provided that, nothing contained in this Section
     3.2(a)(v) shall be taken to relieve the Guarantee Trustee, upon the
     occurrence of an Event of Default, of its obligation to exercise the rights
     and powers vested in it by this Guarantee Agreement.

          (vi)    The Guarantee Trustee shall not be bound to make any
     investigation into the facts or matters stated in any resolution,
     certificate, statement, instrument, opinion, report, notice, request,
     direction, consent, order, bond, debenture, note, other evidence of
     indebtedness or other paper or document, but the Guarantee Trustee, in its
     discretion, may make such further inquiry or investigation into such facts
     or matters as it may see fit.

          (vii)   The Guarantee Trustee may execute any of the trusts or powers
     hereunder or perform any duties hereunder either directly or by or through
     its agents or attorneys, and the Guarantee Trustee shall not be responsible
     for any misconduct or negligence on the part of any such agent or attorney
     appointed with due care by it hereunder.

          (viii)  Whenever in the administration of this Guarantee Agreement the
     Guarantee Trustee shall deem it desirable to receive instructions with
     respect to enforcing any remedy or right or taking any other action
     hereunder, the Guarantee Trustee (A) may request instructions from the
     Holders, (B) may refrain from enforcing such remedy or right or taking such
     other action until such instructions are received, and (C) shall be
     protected in acting in accordance with such instructions.

     (b)   No provision of this Guarantee Agreement shall be deemed to impose
any duty or obligation on the Guarantee Trustee to perform any act or acts or
exercise any right, power, duty or obligation conferred or imposed on it in any
jurisdiction in which it shall be illegal, or in which the Guarantee Trustee
shall be unqualified or incompetent in accordance with applicable law, to
perform any such act or acts or to exercise any such right, power, duty or
obligation. No permissive power or authority available to the Guarantee Trustee
shall be construed to be a duty to act in accordance with such power and
authority.

      Section 3.3.  Indemnity.

      ONEOK agrees to indemnify the Guarantee Trustee for, and to hold it
harmless against, any loss, liability or expense incurred without negligence or
bad faith on the part of the Guarantee Trustee, arising out of or in connection
with the acceptance or administration of this Guarantee Agreement, including the
costs and expenses of defending itself against any claim or liability in
connection with the exercise or performance of any of its powers or duties
hereunder. The Guarantee Trustee will not claim or exact any lien or charge on
any Guarantee Payments as a result of any amount due to it under this Guarantee
Agreement.  The indemnification provided hereunder shall survive the termination
of this Guarantee Agreement and the resignation or removal of the Guarantee
Trustee.

                                      12
<PAGE>

                        ARTICLE IV.   GUARANTEE TRUSTEE

      Section 4.1.  Guarantee Trustee: Eligibility.

      (a) There shall at all times be a Guarantee Trustee which shall:

               (i)  not be an Affiliate of ONEOK; and

               (ii) be a Person that is eligible pursuant to the Trust Indenture
     Act to act as such and has a combined capital and surplus of at least
     $50,000,000, and shall be a corporation meeting the requirements of Section
     310(a) of the Trust Indenture Act. If such corporation publishes reports of
     condition at least annually, pursuant to law or to the requirements of the
     supervising or examining authority, then, for the purposes of this Section
     and to the extent permitted by the Trust Indenture Act, the combined
     capital and surplus of such corporation shall be deemed to be its combined
     capital and surplus as set forth in its most recent report of condition so
     published.

      (b) If at any time the Guarantee Trustee shall cease to be eligible to so
act under Section 4.1(a), the Guarantee Trustee shall immediately resign in the
manner and with the effect set out in Section 4.2(c).

      (c) If the Guarantee Trustee has or shall acquire any "conflicting
interest" within the meaning of Section 310(b) of the Trust Indenture Act, the
Guarantee Trustee and ONEOK shall in all respects comply with the provisions of
Section 310(b) of the Trust Indenture Act.

      Section 4.2.  Appointment, Removal and Resignation of the Guarantee
Trustee.

      (a)  Subject to Section 4.2(b), the Guarantee Trustee may be appointed or
removed without cause at any time by ONEOK.

      (b)  The Guarantee Trustee shall not be removed until a Successor
Guarantee Trustee has been appointed and has accepted such appointment by
written instrument executed by such Successor Guarantee Trustee and delivered to
ONEOK.

      (c)  The Guarantee Trustee appointed hereunder shall hold office until a
Successor Guarantee Trustee shall have been appointed or until its removal or
resignation. The Guarantee Trustee may resign from office (without need for
prior or subsequent accounting) by an instrument in writing executed by the
Guarantee Trustee and delivered to ONEOK, which resignation shall not take
effect until a Successor Guarantee Trustee has been appointed and has accepted
such appointment by instrument in writing executed by such Successor Guarantee
Trustee and delivered to ONEOK and the resigning Guarantee Trustee.

      (d)  If no Successor Guarantee Trustee shall have been appointed and
accepted appointment as provided in this Section 4.2 within 60 days after
delivery to ONEOK of an instrument of resignation, the resigning Guarantee
Trustee may petition, at the expense of ONEOK, any court of

                                      13
<PAGE>

competent jurisdiction for appointment of a Successor Guarantee Trustee. Such
court may thereupon, after prescribing such notice, if any, as it may deem
proper, appoint a Successor Guarantee Trustee.


                            ARTICLE V.   GUARANTEE

      Section 5.1.  Guarantee.

      ONEOK irrevocably and unconditionally agrees to pay in full to the Holders
the Guarantee Payments (without duplication of amounts theretofore paid by or on
behalf of the Issuer), as and when due, regardless of any defense, right of set-
off or counterclaim which the Issuer may have or assert. ONEOK's obligation to
make a Guarantee Payment may be satisfied by direct payment of the required
amounts by ONEOK to the Holders or by causing the Issuer to pay such amounts to
the Holders.

      Section 5.2.  Waiver of Notice and Demand.

      ONEOK hereby waives notice of acceptance of the Guarantee Agreement and of
any liability to which it applies or may apply, presentment, demand for payment,
any right to require a proceeding first against the Guarantee Trustee, Issuer or
any other Person before proceeding against ONEOK, protest, notice of nonpayment,
notice of dishonor, notice of redemption and all other notices and demands.

      Section 5.3.  Obligations Not Affected.

      The obligations, covenants, agreements and duties of ONEOK under this
Guarantee Agreement shall in no way be affected or impaired by reason of the
happening from time to time of any of the following:

      (a) the release or waiver, by operation of law or otherwise, of the
performance or observance by the Issuer of any express or implied agreement,
covenant, term or condition relating to the Preferred Securities to be performed
or observed by the Issuer;

      (b) the extension of time for the payment by the Issuer of all or any
portion of the Distributions (other than an extension of time for payment of
Distributions that results from the extension of any interest payment period on
the Notes as provided in the Indenture), Redemption Price, Liquidation
Distribution or any other sums payable under the terms of the Preferred
Securities or the extension of time for the performance of any other obligation
under, arising out of, or in connection with, the Preferred Securities;

      (c) any failure, omission, delay or lack of diligence on the part of the
Holders or the Guarantee Trustee to enforce, assert or exercise any right,
privilege, power or remedy conferred on the Holders pursuant to the terms of the
Preferred Securities, or any action on the part of the Issuer granting
indulgence or extension of any kind;

      (d) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement,

                                      14
<PAGE>

composition or readjustment of debt of, or other similar proceedings affecting,
the Issuer or any of the assets of the Issuer;

      (e) any invalidity of, or defect or deficiency in, the Preferred
Securities;

      (f) the settlement or compromise of any obligation guaranteed hereby or
hereby incurred; or

      (g) any other circumstance whatsoever that might otherwise constitute a
legal or equitable discharge or defense of a guarantor, it being the intent of
this Section 5.3 that the obligations of ONEOK hereunder shall be absolute and
unconditional under any and all circumstances.

There shall be no obligation of the Holders to give notice to, or obtain the
consent of, ONEOK with respect to the happening of any of the foregoing.

      Section 5.4.  Rights of Holders.

      ONEOK expressly acknowledges that: (i) this Guarantee Agreement will be
deposited with the Guarantee Trustee to be held for the benefit of the Holders;
(ii) the Guarantee Trustee has the right to enforce this Guarantee Agreement on
behalf of the Holders; (iii) the Holders of a Majority in Liquidation Preference
of the Preferred Securities have the right to direct the time, method and place
of conducting any proceeding for any remedy available to the Guarantee Trustee
in respect of this Guarantee Agreement or exercising any trust or power
conferred upon the Guarantee Trustee under this Guarantee Agreement; and (iv)
any Holder may institute a legal proceeding directly against ONEOK to enforce
its rights under this Guarantee Agreement, without first instituting a legal
proceeding against the Guarantee Trustee, the Issuer or any other Person.

      Section 5.5.  Guarantee of Payment.

      This Guarantee Agreement creates a guarantee of payment and not of
performance or collection. This Guarantee Agreement will not be discharged
except by payment of the Guarantee Payments in full (without duplication of
amounts theretofore paid by the Issuer) or upon distribution of Notes to Holders
as provided in the Trust Agreement.

      Section 5.6.  Subrogation.

      ONEOK shall be subrogated to all (if any) rights of the Holders against
the Issuer in respect of any amounts paid to the Holders by ONEOK under this
Guarantee Agreement and shall have the right to waive payment by the Issuer
pursuant to Section 5.1; provided, however, that ONEOK shall not (except to the
extent required by mandatory provisions of law) be entitled to enforce or
exercise any rights which it may acquire by way of subrogation or any indemnity,
reimbursement or other agreement, in all cases as a result of payment under this
Guarantee Agreement, if, at the time of any such payment, any amounts are due
and unpaid under this Guarantee Agreement. If any amount shall be paid to ONEOK
in violation of the preceding sentence, ONEOK agrees to hold such amount in
trust for the Holders and to pay over such amount to the Holders.

      Section 5.7.  Independent Obligations.

                                      15
<PAGE>

      ONEOK acknowledges that its obligations hereunder are independent of the
obligations of the Issuer with respect to the Preferred Securities and that
ONEOK shall be liable as principal and as debtor hereunder to make Guarantee
Payments pursuant to the terms of this Guarantee Agreement notwithstanding the
occurrence of any event referred to in subsections (a) through (g), inclusive,
of Section 5.3 hereof.


                   ARTICLE VI.   COVENANTS AND SUBORDINATION

      Section 6.1.  Subordination.

      The obligations of ONEOK under this Guarantee Agreement will constitute
unsecured obligations of ONEOK and will rank subordinate and junior in right of
payment to all other liabilities of ONEOK except those made pari passu or
subordinate to such obligations expressly by their terms.

      Section 6.2.  Pari Passu Guarantees.

      The obligations of ONEOK under this Guarantee Agreement shall rank pari
passu with the obligations of ONEOK under any similar Guarantee Agreements
issued by ONEOK on behalf of the holders of preferred securities issued by any
ONEOK Capital Trust (as defined in the Indenture).


                          ARTICLE VII.   TERMINATION

      Section 7.1.  Termination.

      This Guarantee Agreement shall terminate and be of no further force and
effect upon (i) full payment of the Redemption Price of all Preferred
Securities, (ii) the distribution of Notes to the Holders in exchange for all of
the Preferred Securities or (iii) full payment of the amounts payable in
accordance with the Trust Agreement upon liquidation of the Issuer.
Notwithstanding the foregoing, this Guarantee Agreement will continue to be
effective or will be reinstated, as the case may be, if at any time any Holder
must restore payment of any sums paid with respect to Preferred Securities or
this Guarantee Agreement.


                         ARTICLE VIII.   MISCELLANEOUS

      Section 8.1.  Successors and Assigns.

      All guarantees and agreements contained in this Guarantee Agreement shall
bind the successors, assigns, receivers, trustees and representatives of ONEOK
and shall inure to the benefit of the Holders of the Preferred Securities then
outstanding. Except in connection with a consolidation, merger or sale involving
ONEOK that is permitted under Article VIII of the Indenture and pursuant to
which the successor or assignee agrees in writing to perform the Guarantor's
obligations hereunder, ONEOK shall not assign its obligations hereunder.

                                      16
<PAGE>

      Section 8.2.  Amendments.

      Except with respect to any changes which do not adversely affect the
rights of the Holders in any material respect (in which case no consent of the
Holders will be required), this Guarantee Agreement may only be amended with the
prior approval of the Holders of a Majority in Liquidation Amount of Securities
of all the outstanding Preferred Securities. The provisions of Article VI of the
Trust Agreement concerning meetings of the Holders shall apply to the giving of
such approval.

      Section 8.3.  Notices.

      Any notice, request or other communication required or permitted to be
given hereunder shall be in writing, duly signed by the party giving such
notice, and delivered, telecopied or mailed by first class mail as follows:

      (a) if given to ONEOK, to the address set forth below or such other
address, facsimile number or to the attention of such other Person as ONEOK may
give notice to the Holders:

               ONEOK, INC.
               100 West Fifth Street
               Tulsa, Oklahoma 74103
               Facsimile No.: (918) ___-____
               Attention: Treasurer

      (b) if given to the Issuer, in care of the Guarantee Trustee, at the
Issuer's (and the Guarantee Trustee's) respective addresses set forth below or
such other address as the Guarantee Trustee on behalf of the Issuer may give
notice to the Holders:

               ONEOK Capital Trust I
               __________________
               __________________
               __________________
               Attention: _______

               with a copy to:

               __________________
               __________________
               __________________
               __________________
               Facsimile No.:  (___)-___-____
               Attention: _______

      (c) if given to the Guarantee Trustee, at the Guarantee Trustee's address
set forth below or such other address as the Guarantee Trustee may give notice
to the Holders:

               __________________

                                      17
<PAGE>

         ____________________
         Facsimile No.:  (___)-___-____
         Attention: _________

     (d) if given to any Holder, at the address set forth on the books and
records of the Issuer.

     All notices hereunder shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid, except that if a notice or other document is refused delivery
or cannot be delivered because of a changed address of which no notice was
given, such notice or other document shall be deemed to have been delivered on
the date of such refusal or inability to deliver.

     Section 8.4.   Benefit.

     This Guarantee Agreement is solely for the benefit of the Holders and is
not separately transferable from the Preferred Securities.

     Section 8.5.   Interpretation.

     In this Guarantee Agreement, unless the context otherwise requires:

     (a) capitalized terms used in this Guarantee Agreement but not defined in
the preamble hereto have the respective meanings assigned to them in Section
1.1;

     (b) a term defined anywhere in this Guarantee Agreement has the same
meaning throughout;

     (c) all references to "the Guarantee Agreement" or "this Guarantee
Agreement" are to this Guarantee Agreement as modified, supplemented or amended
from time to time;

     (d) all references in this Guarantee Agreement to Articles and Sections are
to Articles and Sections of this Guarantee Agreement unless otherwise specified;

     (e) a term defined in the Trust Indenture Act has the same meaning when
used in this Guarantee Agreement unless otherwise defined in this Guarantee
Agreement or unless the context otherwise requires;

     (f) a reference to the singular includes the plural and vice versa; and

     (g) the masculine, feminine or neuter genders used herein shall include the
masculine, feminine and neuter genders.

                                      18
<PAGE>

     Section 8.6.   Governing Law.

     THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO THE
CONFLICT OF LAW PRINCIPLES THEREOF.


                 [remainder of page intentionally left blank]

                                      19
<PAGE>

     This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

     THIS GUARANTEE AGREEMENT is executed as of the day and year first above
written.

                                    ONEOK, INC.



                                    By:  ___________________________
                                    Name:
                                    Title:

                                    Executed in __________________.



                                    _________________________________
                                         as Guarantee Trustee



                                    By:
                                    Name:____________________________
                                    Title:

                                    Executed in ___________________.

                                      20

<PAGE>

                                                                    EXHIBIT 23.1


                         Independent Auditors' Consent

The Board of Directors
ONEOK, Inc.

We consent to the incorporation by reference herein of our report on the
Consolidated Financial Statements of ONEOK, Inc. and subsidiaries as of August
31, 1998 and 1997, and for each of the years in the three-year period ended
August 31, 1998, which report appears in the August 31, 1998, Annual Report on
Form 10-K of ONEOK, Inc. and to the reference to our firm under the heading
"Experts" in the prospectus.


                                                                    /s/ KPMG LLP

Tulsa, Oklahoma
July 12, 1999

<PAGE>

                                                                    EXHIBIT 23.2

                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

As independent pubic accountants, we hereby consent to the incorporation by
reference in this registration statement of our report dated March 26, 1999,
incorporated by reference in Southwest Gas Corporation's Annual Report on Form
10-K for the year ended December 31, 1998 and ONEOK, Inc.'s Current Report on
Form 8-K dated April 15, 1999, and to all references to our Firm included in
this registration statement.

                                                             ARTHUR ANDERSEN LLP

Las Vegas, Nevada
July 12, 1999


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission