ILLINOIS POWER CO
S-3/A, 1995-11-22
ELECTRIC & OTHER SERVICES COMBINED
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<PAGE>   1
 
   
   AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 22, 1995
    
   
                                                   REGISTRATION NOS. 33-63581-01
    
   
                                                              33-63581
    
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                               ------------------
 
                                    FORM S-3
   
                                 PRE-EFFECTIVE
    
   
                                AMENDMENT NO. 1
    
   
                                       TO
    
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               ------------------
 
                             ILLINOIS POWER COMPANY
             (Exact name of registrant as specified in its charter)
                                    ILLINOIS
         (State or other jurisdiction of incorporation or organization)
                                   37-0344645
                      (I.R.S. Employer Identification No.)
                                 LARRY D. HAAB
                CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                             ILLINOIS POWER COMPANY
                             500 SOUTH 27TH STREET
                            DECATUR, ILLINOIS 62525
                                 (217) 424-6600
                           ILLINOIS POWER FINANCING I
      (Exact name of registrant as specified in its Declaration of Trust)
                                    DELAWARE
         (State or other jurisdiction of incorporation or organization)
                                  APPLIED FOR
                      (I.R.S. Employer Identification No.)
                               C/O LARRY D. HAAB
                CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                             ILLINOIS POWER COMPANY
                             500 SOUTH 27TH STREET
                            DECATUR, ILLINOIS 62525
                                 (217) 424-6600
 
  (Address, including zip code, and telephone number, including area code, of
        registrants' principal executive offices and agent for service)
                  PLEASE SEND COPIES OF ALL COMMUNICATIONS TO:
 
                             ROBERT J. REGAN, ESQ.
                             SCHIFF HARDIN & WAITE
                                7200 SEARS TOWER
                            CHICAGO, ILLINOIS 60606
                                 (312) 876-1000
                               KEVIN STACEY, ESQ.
                               REID & PRIEST LLP
                              40 WEST 57TH STREET
                            NEW YORK, NEW YORK 10019
                                 (212) 603-2144
 
                               ------------------
    Approximate date of commencement of proposed sale to the public: As soon as
practicable after the effective date of this Registration Statement.
                               ------------------
    If the only securities being registered on this Form are being 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, please check the following box:  / /
    If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please 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 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.  /X/
                               ------------------
 
   
                        CALCULATION OF REGISTRATION FEE
    
- --------------------------------------------------------------------------------
 
   
<TABLE>
<CAPTION>
- ------------------------------------------------------------------------------------------------------------------------
                                                                                           PROPOSED
                                                                        PROPOSED            MAXIMUM
                                                      AMOUNT             MAXIMUM           AGGREGATE          AMOUNT OF
    TITLE OF EACH CLASS OF SECURITIES TO BE            TO BE         OFFERING PRICE        OFFERING         REGISTRATION
                    REGISTERED                     REGISTERED(1)    PER UNIT(1)(2)(3)   PRICE(1)(2)(3)         FEE(1)
- ------------------------------------------------------------------------------------------------------------------------
<S>                                             <C>                <C>                <C>                <C>
Illinois Power Financing I Preferred Securities
- ------------------------------------------------
Illinois Power Company Subordinated
  Debentures(4)
- ------------------------------------------------
Illinois Power Company Guarantee and other
  back-up obligations with respect to Illinois
  Power Financing I Preferred Securities(4)
- ------------------------------------------------------------------------------------------------------------------------
Total...........................................   $100,000,000.00        100%          $100,000,000.00      $34,483.00
</TABLE>
    
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
   
(1) Pursuant to Rule 457(o) under the Securities Act of 1933, which permits the
    registration fee to be calculated on the basis of the maximum aggregate
    offering price of all the securities listed, the table does not specify by
    each class information as to the amount to be registered, proposed maximum
    offering price per unit or proposed maximum aggregate offering price. This
    registration fee was paid at the time of the initial filing of this
    Registration Statement on October 20, 1995.
    
(2) Estimated solely for the purpose of determining the registration fee.
(3) Exclusive of accrued interest and dividends, if any.
   
(4) No separate consideration will be received for Illinois Power Company's
    Subordinated Debentures, its Guarantee or its other back-up obligations with
    respect to Illinois Power Financing I Preferred Securities.
    
                               ------------------
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 THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>   2
 
     INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A
     REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE
     SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR
     MAY OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT
     BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR
     THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE
     SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE
     UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS
     OF ANY SUCH STATE.
 
   
                 PRELIMINARY PROSPECTUS DATED NOVEMBER 22, 1995
    
PROSPECTUS
 
                         4,000,000 PREFERRED SECURITIES
 
[LOGO]                     ILLINOIS POWER FINANCING I
   
          % TRUST ORIGINATED PREFERRED SECURITIES SM ("TOPRS SM")
    
                (LIQUIDATION AMOUNT $25 PER PREFERRED SECURITY)
                  GUARANTEED TO THE EXTENT SET FORTH HEREIN BY
 
                             ILLINOIS POWER COMPANY
                            ------------------------
 
     The   % Trust Originated Preferred Securities (the "Preferred Securities")
offered hereby represent preferred undivided beneficial interests in the assets
of Illinois Power Financing I, a statutory business trust formed under the laws
of the State of Delaware ("Illinois Power Financing I" or the "Trust"). Illinois
Power Company, an Illinois corporation ("Illinois Power"), will directly or
indirectly own all the common securities (the "Common Securities" and, together
with the Preferred Securities, the "Trust Securities") representing undivided
beneficial interests in the assets of Illinois Power Financing I. Illinois Power
Financing I exists for the sole purpose of issuing the Preferred Securities and
Common Securities and investing the proceeds thereof in an equivalent amount of
  %
                                                        (continued on next page)
 
     SEE "RISK FACTORS" COMMENCING ON PAGE 5 OF THIS PROSPECTUS FOR CERTAIN
INFORMATION RELEVANT TO AN INVESTMENT IN THE PREFERRED SECURITIES, INCLUDING THE
PERIOD AND CIRCUMSTANCES DURING AND UNDER WHICH PAYMENTS OF DISTRIBUTIONS ON THE
PREFERRED SECURITIES MAY BE DEFERRED AND THE RELATED UNITED STATES FEDERAL
INCOME TAX CONSEQUENCES OF SUCH DEFERRAL.
 
   
     Application has been made to list the Preferred Securities on the New York
Stock Exchange. If so 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. See "Underwriting."
    
                            ------------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
  EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE
     SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION
       PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
        REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
   
<TABLE>
<CAPTION>
- -------------------------------------------------------------------------------------------------------
- -------------------------------------------------------------------------------------------------------
                                           INITIAL PUBLIC        UNDERWRITING          PROCEEDS TO
                                          OFFERING PRICE(1)      COMMISSION(2)         TRUST(3)(4)
- -------------------------------------------------------------------------------------------------------
<S>                                     <C>                  <C>                  <C>
Per Preferred Security................            $                   (3)                   $
- -------------------------------------------------------------------------------------------------------
Total.................................  $                             (3)         $
- -------------------------------------------------------------------------------------------------------
- -------------------------------------------------------------------------------------------------------
</TABLE>
    
 
(1) Plus accrued distributions, if any, from             , 1995.
(2) Illinois Power Financing I and Illinois Power have agreed to indemnify the
    several Underwriters against certain liabilities, including liabilities
    under the Securities Act of 1933, as amended. See "Underwriting."
(3) In view of the fact that the proceeds of the sale of the Preferred
    Securities will be invested in the Subordinated Debentures, Illinois Power
    has agreed to pay to the Underwriters as compensation (the "Underwriters'
    Compensation") for their arranging the investment therein of such proceeds
    $       per Preferred Security (or $       in the aggregate); provided, that
    such compensation for sales of 10,000 or more Preferred Securities to a
    single purchaser will be $       per Preferred Security. Therefore, to the
    extent of such sales, the actual amount of Underwriters' Compensation will
    be less than the aggregate amount specified in the preceding sentence. See
    "Underwriting."
(4) Expenses of the offering which are payable by Illinois Power are estimated
    to be $400,000.
                            ------------------------
 
     The Preferred Securities offered hereby are offered severally by the
Underwriters, as specified herein, subject to receipt and acceptance by them and
subject to their right to reject any order in whole or in part. It is expected
that delivery of the Preferred Securities will be made only in book-entry form
through the facilities of The Depository Trust Company, on or about
            , 1995.
                            ------------------------
MERRILL LYNCH & CO.
             SMITH BARNEY INC.
                           DEAN WITTER REYNOLDS INC.
                                       A.G. EDWARDS & SONS, INC.
                                               PAINEWEBBER INCORPORATED
                            ------------------------
 
               The date of this Prospectus is             , 1995.
 
   
SM   "Trust Originated Preferred Securities" and "TOPrS" are service marks of
Merrill Lynch & Co., Inc.
    
<PAGE>   3
 
(continued from previous page)
 
   
Junior Subordinated Deferrable Interest Notes due 2044 (the "Subordinated
Debentures") of Illinois Power. Upon an event of a default under the Declaration
(as defined herein), the holders of Preferred Securities will have a preference
over the holders of the Common Securities with respect to payments in respect of
distributions and payments upon liquidation, redemption and otherwise.
    
 
   
    Holders of the Preferred Securities are entitled to receive cumulative cash
distributions at an annual rate of    % of the liquidation amount of $25 per
Preferred Security, accruing from the date of original issuance and payable
quarterly in arrears on March 31, June 30, September 30, and December 31 of each
year, commencing December 31, 1995 ("distributions"). The payment of
distributions out of moneys held by Illinois Power Financing I and payments on
termination of Illinois Power Financing I or the redemption of Preferred
Securities, as set forth below, are guaranteed by Illinois Power (the
"Guarantee") to the extent Illinois Power Financing I has funds available
therefor as described under "Description of the Preferred Securities Guarantee."
The obligations of Illinois Power under the Guarantee are subordinate and junior
in right of payment to all other liabilities of Illinois Power and pari passu
with the most senior preferred stock issued, from time to time, if any, by
Illinois Power. The obligations of Illinois Power under the Subordinated
Debentures are subordinate and junior in right of payment to all present and
future Senior Indebtedness (as defined herein) of Illinois Power, which
aggregated approximately $2.2 billion at September 30, 1995, and rank pari passu
with Illinois Power's general unsecured creditors other than holders of Senior
Indebtedness.
    
 
    The distribution rate and the distribution payment date and other payment
dates for the Preferred Securities will correspond to the interest rate and
interest payment date and other payment dates on the Subordinated Debentures,
which will be the sole assets of Illinois Power Financing I. As a result, if
principal or interest is not paid on the Subordinated Debentures, no amounts
will be paid on the Preferred Securities. If Illinois Power does not make
principal or interest payments on the Subordinated Debentures, Illinois Power
Financing I will not have sufficient funds to make distributions on the
Preferred Securities, in which event, the Guarantee will not apply to such
distributions until Illinois Power Financing I has sufficient funds available
therefor.
 
    Illinois Power has the right to defer payments of interest on the
Subordinated Debentures by extending the interest payment period on the
Subordinated Debentures at any time for up to 20 consecutive quarters (each, an
"Extension Period"). If interest payments are so deferred, distributions on the
Preferred Securities will also be deferred. During such Extension Period,
distributions will continue to accrue with interest thereon (to the extent
permitted by applicable law) at an annual rate of    % per annum compounded
quarterly, and during any Extension Period, holders of Preferred Securities will
be required to include deferred interest income in their gross income for United
States federal income tax purposes in advance of receipt of the cash
distributions with respect to such deferred interest payments. There could be
multiple Extension Periods of varying lengths throughout the term of the
Subordinated Debentures. See "Description of the Subordinated Debentures --
Option to Extend Interest Payment Period." See "Risk Factors -- Option to Extend
Interest Payment Period" and "United States Federal Income Taxation -- Original
Issue Discount." In the event of any such deferral, the holders of the Preferred
Securities do not have the right to appoint a special representative or trustee
or otherwise act to protect their interests.
 
    The Subordinated Debentures are redeemable by Illinois Power, in whole or in
part, from time to time, on or after            , 2000, or at any time in
certain circumstances upon the occurrence of a Tax Event (as defined herein). If
Illinois Power redeems Subordinated Debentures, Illinois Power Financing I must
redeem Trust Securities having an aggregate liquidation amount equal to the
aggregate principal amount of the Subordinated Debentures so redeemed at $25 per
Preferred Security plus accrued and unpaid distributions thereon (the
"Redemption Price") to the date fixed for redemption. See "Description of the
Preferred Securities -- Mandatory Redemption." The Preferred Securities will be
redeemed upon maturity of the Subordinated Debentures. The Subordinated
Debentures mature on            , 2044. In addition, upon the occurrence of a
Special Event (as defined herein), unless the Subordinated Debentures are
redeemed in the limited circumstances described herein, Illinois Power Financing
I shall be terminated, with the result that the Subordinated Debentures will be
distributed to the holders of the Preferred Securities, on a pro rata basis, in
lieu of any cash distribution. See "Description of the Preferred Securities --
Special Event Redemption or Distribution." In the case of the occurrence of a
Special Event that is a Tax Event, Illinois Power will have the right in certain
circumstances to redeem the Subordinated Debentures, which would result in the
redemption by Illinois Power Financing I of Trust Securities in the same amount
on a pro rata basis. If the Subordinated Debentures are distributed to the
holders of the Preferred Securities, Illinois Power will use its best efforts to
have the Subordinated Debentures listed on the New York Stock Exchange or on
such other exchange as the Preferred Securities are then listed. See
"Description of the Preferred Securities -- Special Event Redemption or
Distribution" and "Description of the Subordinated Debentures."
 
    In the event of the involuntary or voluntary dissolution, winding up or
termination of Illinois Power Financing I, the holders of the Preferred
Securities will be entitled to receive for each Preferred Security a liquidation
amount of $25 plus accrued and unpaid distributions thereon (including interest
thereon) to the date of payment, unless, in connection with such dissolution,
winding up or termination, the Subordinated Debentures are distributed to the
holders of the Preferred Securities. See "Description of the Preferred
Securities -- Liquidation Distribution Upon Termination."
                            ------------------------
 
    IN CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR EFFECT
TRANSACTIONS THAT STABILIZE OR MAINTAIN THE MARKET PRICE OF THE SECURITIES
OFFERED HEREBY AT LEVELS ABOVE THOSE THAT MIGHT OTHERWISE PREVAIL IN THE OPEN
MARKET. SUCH TRANSACTIONS MAY BE EFFECTED ON THE NEW YORK STOCK EXCHANGE, IN THE
OVER-THE-COUNTER MARKET OR OTHERWISE. SUCH STABILIZING TRANSACTIONS, IF
COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
 
                                        2
<PAGE>   4
 
                             AVAILABLE INFORMATION
 
     Illinois Power is subject to the informational requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and in
accordance therewith files reports, information statements and other information
with the Securities and Exchange Commission (the "Commission"). Reports,
information statements and other information filed by Illinois Power with the
Commission may be inspected and copied at the public reference facilities
maintained by the Commission at Room 1024, 450 Fifth Street, N.W., Washington,
D.C. 20549, and at the Commission's Regional Offices located at Suite 1400,
Northwestern Atrium Center, 500 West Madison Street, Chicago, Illinois 60661 and
at the 13th Floor, Seven World Trade Center, New York, New York 10048. Copies of
such material may be obtained from the public reference section of the
Commission, 450 Fifth Street, N.W. Washington, D.C. 20549, at prescribed rates.
Such reports, information statements and other information concerning Illinois
Power may also be inspected at the offices of the New York Stock Exchange, 20
Broad Street, New York, New York 10005 and the Chicago Stock Exchange, 440 South
LaSalle Street, Chicago, Illinois 60605, on which exchanges certain of Illinois
Power's securities are listed. In addition, such reports, information statements
and other information concerning Illinois Power can be inspected at the
principal office of Illinois Power, 500 South 27th Street, Decatur, Illinois
62525.
 
     This Prospectus does not contain all the information set forth in the
Registration Statement on Form S-3 (together with all amendments and exhibits
thereto, the "Registration Statement"), which Illinois Power and Illinois Power
Financing I have filed with the Commission under the Securities Act of 1933, as
amended (the "Securities Act"). Statements contained or incorporated by
reference herein concerning the provisions of documents are necessarily
summaries of such documents, and each statement is qualified in its entirety by
reference to the Registration Statement.
 
     No separate financial statements of Illinois Power Financing I have been
included herein. Illinois Power and Illinois Power Financing I do not consider
that such financial statements would be material to holders of Preferred
Securities because Illinois Power Financing I is a newly formed special purpose
entity, has no operating history and no independent operations and is not
engaged in, and does not propose to engage in, any activity other than as set
forth below. See "Illinois Power Financing I."
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
     The following documents heretofore filed by Illinois Power with the
Commission pursuant to the Exchange Act are incorporated herein by reference:
 
          1. Illinois Power's Annual Report on Form 10-K for the year ended
     December 31, 1994;
 
   
          2. Illinois Power's Quarterly Reports on Form 10-Q for the quarters
     ended March 31, 1995, June 30, 1995 and September 30, 1995; and
    
 
          3. Illinois Power's Current Report on Form 8-K dated August 11, 1995.
 
     All documents subsequently filed by Illinois Power pursuant to Sections
13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this Prospectus
and prior to the termination of the offering of the Preferred Securities offered
hereby, shall be deemed to be incorporated by reference in this Prospectus and
to be a part hereof from the date of filing of such documents. Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for purposes of this
Prospectus to the extent that a statement contained herein or in any other
subsequently filed document which also is or is deemed to be incorporated by
reference herein modifies or supersedes such statement. Any such statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Prospectus.
 
     ILLINOIS POWER WILL PROVIDE WITHOUT CHARGE TO EACH PERSON TO WHOM A COPY OF
THIS PROSPECTUS HAS BEEN DELIVERED, ON THE WRITTEN OR ORAL REQUEST OF SUCH
PERSON, A COPY OF ANY OR ALL OF THE DOCUMENTS REFERRED TO ABOVE WHICH HAVE BEEN
OR MAY BE INCORPORATED IN THIS PROSPECTUS BY REFERENCE, OTHER THAN EXHIBITS TO
SUCH DOCUMENTS WHICH ARE NOT SPECIFICALLY INCORPORATED BY REFERENCE INTO THE
INFORMATION THAT THIS PROSPECTUS INCORPORATES. REQUEST FOR SUCH COPIES SHOULD BE
DIRECTED TO MS. CYNTHIA G. STEWARD, CONTROLLER, ILLINOIS POWER COMPANY, 500
SOUTH 27TH STREET, DECATUR, ILLINOIS 62525, TELEPHONE NUMBER (217) 424-6600.
 
                                        3
<PAGE>   5
 
                               PROSPECTUS SUMMARY
 
     The following summary is qualified in its entirety by reference to the
detailed information appearing elsewhere in this Prospectus.
 
     Preferred Securities Offered. 4,000,000      % Trust Originated Preferred
Securities evidencing preferred undivided beneficial interests in the assets of
Illinois Power Financing I are offered hereby. Holders of the Preferred
Securities are entitled to receive cumulative cash distributions at an annual
rate of      % of the liquidation amount of $25 per Preferred Security, accruing
from the date of original issuance and payable quarterly in arrears on March 31,
June 30, September 30 and December 31 of each year, commencing on December 31,
1995. The distribution rate and the distribution and other payment dates for the
Preferred Securities will correspond to the interest rate and interest and other
payment dates on the Subordinated Debentures, which will be the sole assets of
Illinois Power Financing I. As a result, if principal or interest is not paid on
the Subordinated Debentures, no amounts will be paid on the Preferred
Securities. See "Description of the Preferred Securities."
 
     Subordinated Debentures. Illinois Power Financing I will invest the
proceeds from the issuance of the Preferred Securities and Common Securities in
an equivalent amount of      % Subordinated Debentures due          , 2044 of
Illinois Power. The Subordinated Debentures will be subordinate and junior in
right of payment to all Senior Indebtedness of Illinois Power. See "Description
of the Subordinated Debentures -- Subordination."
 
   
     Preferred Securities Guarantee. Payment of distributions out of moneys held
by Illinois Power Financing I, and payments on termination of Illinois Power
Financing I or the redemption of Preferred Securities are guaranteed by Illinois
Power to the extent Illinois Power Financing I has funds available therefor. If
Illinois Power does not make principal or interest payments on the Subordinated
Debentures, Illinois Power Financing I will not have sufficient funds to make
distributions on the Preferred Securities, in which event the Guarantee will not
apply to such distributions until Illinois Power Financing I has sufficient
funds available therefor. See "Description of the Preferred Securities
Guarantee" and "Effect of Obligations Under the Subordinated Debentures and the
Guarantee" herein. The obligations of Illinois Power under the Guarantee are
subordinate and junior in right of payment to all other liabilities of Illinois
Power and will rank pari passu with the most senior preferred stock issued by
Illinois Power. See "Risk Factors -- Ranking of Subordinate Obligations Under
the Guarantee and Subordinated Debentures" and "Description of the Preferred
Securities Guarantee."
    
 
     Interest Deferral. Illinois Power has the right to defer payments of
interest on the Subordinated Debentures by extending the interest payment period
on the Subordinated Debentures, at any time, for up to 20 consecutive quarters.
If interest payments on the Subordinated Debentures are so deferred,
distributions on the Preferred Securities will also be deferred. During any such
deferral, distributions will continue to accrue with interest thereon (to the
extent permitted by law) as described herein. There could be multiple Extension
Periods of varying lengths throughout the term of the Subordinated Debentures.
During an Extension Period, holders of Preferred Securities will be required to
include deferred interest income in their gross income in advance of receipt of
the cash interest payments attributable thereto. See "Description of the
Preferred Securities -- Voting Rights," "Description of the Subordinated
Debentures -- Option to Extend Interest Payment Period" and "United States
Federal Income Taxation -- Original Issue Discount," and "-- Market Discount and
Bond Premium."
 
     Redemption. The Subordinated Debentures are redeemable by Illinois Power
(in whole or in part) from time to time, on or after                  , 2000 or
at any time in certain circumstances upon the occurrence of a Tax Event. If the
Subordinated Debentures are redeemed, Illinois Power Financing I must redeem
Trust Securities having an aggregate liquidation amount equal to the aggregate
principal amount of Subordinated Debentures so redeemed. The Preferred
Securities will be redeemed upon maturity of the Subordinated Debentures. See
"Description of the Preferred Securities -- Mandatory Redemption."
 
                                        4
<PAGE>   6
 
                                  RISK FACTORS
 
     Prospective purchasers of Preferred Securities should carefully review the
information contained elsewhere in this Prospectus and should particularly
consider the following matters.
 
RANKING OF SUBORDINATE OBLIGATIONS UNDER THE GUARANTEE AND SUBORDINATED
DEBENTURES
 
     Illinois Power's obligations under the Guarantee are subordinate and junior
in right of payment to all liabilities of Illinois Power and pari passu with the
most senior preferred stock issued, from time to time, if any, by Illinois
Power. The obligations of Illinois Power under the Subordinated Debentures are
subordinate and junior in right of payment to all present and future Senior
Indebtedness of Illinois Power and pari passu with obligations to or rights of
Illinois Power's general unsecured creditors other than holders of Senior
Indebtedness. As of September 30, 1995, Senior Indebtedness aggregated
approximately $2.2 billion. There are no terms in the Preferred Securities, the
Subordinated Debentures or the Guarantee that limit Illinois Power's ability to
incur additional indebtedness, including indebtedness that ranks senior to the
Subordinated Debentures and the Guarantee. See "Description of Preferred
Securities Guarantee -- Status of the Guarantee" and "Description of the
Subordinated Debentures -- Subordination" herein.
 
RIGHTS UNDER THE GUARANTEE
 
     The Guarantee will be qualified as an indenture under the Trust Indenture
Act of 1939, as amended (the "Trust Indenture Act"). Wilmington Trust Company
will act as indenture trustee under the Guarantee for the purposes of compliance
with the provisions of the Trust Indenture Act (the "Guarantee Trustee"). The
Guarantee Trustee will hold the Guarantee for the benefit of the holders of the
Preferred Securities.
 
   
     The Guarantee guarantees to the holders of the Preferred Securities the
payment of (i) any accrued and unpaid distributions that are required to be paid
on the Preferred Securities, to the extent Illinois Power Financing I has funds
available therefor, (ii) the Redemption Price, including all accrued and unpaid
distributions with respect to Preferred Securities called for redemption by
Illinois Power Financing I, to the extent Illinois Power Financing I has funds
available therefor, and (iii) upon a voluntary or involuntary dissolution,
winding-up or termination of Illinois Power Financing I (other than in
connection with the distribution of Subordinated Debentures to the holders of
Preferred Securities or a redemption of all the Preferred Securities), the
lesser of (a) the aggregate of the liquidation amount and all accrued and unpaid
distributions on the Preferred Securities to the date of the payment to the
extent Illinois Power Financing I has funds available therefor or (b) the amount
of assets of Illinois Power Financing I remaining available for distribution to
holders of the Preferred Securities upon termination of Illinois Power Financing
I. The holders of a majority in liquidation amount 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 or to direct the exercise of
any trust or power conferred upon the Guarantee Trustee under the Guarantee. If
the Guarantee Trustee fails to enforce the Guarantee, any holder of Preferred
Securities may institute a legal proceeding directly against Illinois Power to
enforce the Guarantee Trustee's rights under the Guarantee without first
instituting a legal proceeding against Illinois Power Financing I, the Guarantee
Trustee or any other person or entity. If Illinois Power were to default on its
obligation to pay amounts payable on the Subordinated Debentures, Illinois Power
Financing I would lack available funds for the payment of distributions or
amounts payable on redemption of the Preferred Securities or otherwise, and, in
such event, holders of the Preferred Securities would not be able to rely upon
the Guarantee for payment of such amounts. Instead, holders of the Preferred
Securities would rely on the enforcement by the Property Trustee of its rights
as registered holder of the Subordinated Debentures against Illinois Power
pursuant to the terms of the Subordinated Debentures. See "Description of the
Preferred Securities Guarantee" and "Description of the Subordinated
Debentures." The Declaration provides that each holder of Preferred Securities,
by acceptance thereof, agrees to the provisions of the Guarantee, including the
subordination provisions thereof, and the Indenture (as defined herein).
    
 
                                        5
<PAGE>   7
 
ENFORCEMENT OF CERTAIN RIGHTS BY HOLDERS OF PREFERRED SECURITIES
 
     If (i) Illinois Power Financing I fails to pay distributions in full on the
Preferred Securities for six consecutive quarterly distribution periods or (ii)
a Declaration Event of Default (as defined herein) occurs and is continuing,
then the holders of Preferred Securities would rely on the enforcement by the
Property Trustee (as defined herein) of its rights as a holder of the
Subordinated Debentures against Illinois Power. In addition, the holders of a
majority in liquidation amount of the Preferred Securities will have the right
to direct the time, method, and place of conducting any proceeding for any
remedy available to the Property Trustee or to direct the exercise of any trust
or power conferred upon the Property Trustee under the Declaration, including
the right to direct the Property Trustee to exercise the remedies available to
it as a holder of the Subordinated Debentures. If the Property Trustee fails to
enforce its rights under the Subordinated Debentures to the fullest extent
permitted by law, a holder of Preferred Securities may institute a legal
proceeding directly against Illinois Power to enforce the Property Trustee's
rights under the Subordinated Debentures without first instituting any legal
proceeding against the Property Trustee or any other person or entity.
 
OPTION TO EXTEND INTEREST PAYMENT PERIOD
 
     Illinois Power has the right under the Indenture to defer payments of
interest on the Subordinated Debentures by extending the interest payment period
at any time, and from time to time, on the Subordinated Debentures. As a
consequence of such an extension, quarterly distributions on the Preferred
Securities would be deferred (but despite such deferral would continue to accrue
with interest thereon compounded quarterly to the extent permitted by applicable
law) by Illinois Power Financing I during any such Extension Period. Such right
to extend the interest payment period for the Subordinated Debentures is limited
to a period not exceeding 20 consecutive quarters. In the event that Illinois
Power exercises this right to defer interest payments, then (a) Illinois Power
shall not declare or pay dividends on, or make a distribution with respect to,
or redeem, purchase or acquire, or make a liquidation payment with respect to,
any of its capital stock, provided, however, Illinois Power may declare and pay
a stock dividend where the dividend stock is the same stock as that on which the
dividend is being paid, (b) Illinois Power shall not make any payment of
interest, principal or premium, if any, on or repay, repurchase or redeem any
debt securities (including guarantees) issued by Illinois Power which rank pari
passu with or junior to the Subordinated Debentures, and (c) Illinois Power
shall not make any guarantee payments with respect to the foregoing (other than
pursuant to the Guarantee). Prior to the termination of any such Extension
Period, Illinois Power may further extend the interest payment period; provided,
that such Extension Period, together with all such previous and further
extensions thereof, may not exceed 20 consecutive quarters. Upon the termination
of any Extension Period and the payment of all amounts then due, Illinois Power
may commence a new Extension Period, subject to the above requirements. See
"Description of the Preferred Securities -- Distributions" and "Description of
the Subordinated Debentures -- Option to Extend Interest Payment Period."
 
     Because Illinois Power has the right to extend the interest payment period
for the Subordinated Debentures, the Preferred Securities will be treated as
having been issued with original issue discount ("OID") for United States
federal income tax purposes. Should Illinois Power exercise its right to defer
payments of interest by extending the interest payment period, each holder of
Preferred Securities will continue to accrue income (as OID) in respect of the
deferred interest allocable to its Preferred Securities for United States
federal income tax purposes, which will be allocated, but not distributed, to
holders of record of Preferred Securities. As a result, each such holder of
Preferred Securities will recognize income for United States federal income tax
purposes in advance of the receipt of cash, regardless of their method of
accounting, and will not receive the cash from Illinois Power Financing I
related to such income if such holder disposes of its Preferred Securities prior
to the record date for the date on which distributions of such amounts are made.
Illinois Power has no current intention of exercising its right to defer
payments of interest by extending the interest payment period on the
Subordinated Debentures. However, should Illinois Power determine to exercise
such right in the future, the market price of the Preferred Securities is likely
to be affected. A holder that disposes of its Preferred Securities during an
Extension Period, therefore, might not receive the same return on its investment
as a holder that continues to hold its Preferred Securities. In addition, as a
result of
 
                                        6
<PAGE>   8
 
the existence of Illinois Power's right to defer interest payments, the market
price of the Preferred Securities (which represent an undivided beneficial
interest in the Subordinated Debentures) may be more volatile than other
securities on which OID accrues that do not have such rights. See "United States
Federal Income Taxation -- Original Issue Discount."
 
SPECIAL EVENT REDEMPTION OR DISTRIBUTION
 
   
     Upon the occurrence of a Special Event, Illinois Power Financing I shall be
terminated, except in the limited circumstance described below, with the result
that, after satisfaction of liabilities to creditors, the Subordinated
Debentures would be distributed to the holders of the Trust Securities in
connection with the termination of Illinois Power Financing I. In the case of a
Special Event that is a Tax Event, in certain circumstances Illinois Power shall
have the right to redeem the Subordinated Debentures, in whole or in part, in
lieu of a distribution of the Subordinated Debentures by Illinois Power
Financing I; in which event Illinois Power Financing I will redeem the Trust
Securities on a pro rata basis to the same extent as the Subordinated Debentures
are redeemed by Illinois Power. See "Description of the Preferred Securities --
Special Event Redemption or Distribution."
    
 
     There can be no assurance as to the market prices for the Preferred
Securities or the Subordinated Debentures that may be distributed in exchange
for Preferred Securities if a termination of Illinois Power Financing I were to
occur. Accordingly, the Preferred Securities that an investor may purchase,
whether pursuant to the offer made hereby or in the secondary market, or the
Subordinated Debentures that a holder of Preferred Securities may receive on
termination of Illinois Power Financing I, may trade at a discount to the price
that the investor paid to purchase the Preferred Securities offered hereby.
Because holders of Preferred Securities may receive Subordinated Debentures upon
the occurrence of a Special Event, prospective purchasers of Preferred
Securities are also making an investment decision with regard to the
Subordinated Debentures and should carefully review all the information
regarding the Subordinated Debentures contained herein. See "Description of the
Preferred Securities -- Special Event Redemption or Distribution" and
"Description of the Subordinated Debentures -- General."
 
LIMITED VOTING RIGHTS
 
     Holders of Preferred Securities will have limited voting rights and will
not be entitled to vote to appoint, remove or replace, or to increase or
decrease the number of, Illinois Power Trustees (as defined herein), which
voting rights are vested exclusively in the holder of the Common Securities. See
"Description of the Preferred Securities -- Voting Rights."
 
TRADING PRICE
 
     The Preferred Securities may trade at a price that does not fully reflect
the value of accrued but unpaid interest with respect to the underlying
Subordinated Debentures. A holder who disposes of his Preferred Securities
between record dates for payments of distributions thereon will be required to
include accrued but unpaid interest on the Subordinated Debentures through the
date of disposition in income as ordinary income (i.e., OID), and to add such
amount to his adjusted tax basis in his pro rata share of the underlying
Subordinated Debentures deemed disposed of. To the extent the selling price is
less than the holder's adjusted tax basis (which will include, in the form of
OID, all accrued but unpaid interest), a holder will recognize a capital loss.
Subject to certain limited exceptions, capital losses cannot be applied to
offset ordinary income for United States federal income tax purposes. See
"United States Federal Income Taxation -- Original Issue Discount" and "-- Sales
of Preferred Securities."
 
                                        7
<PAGE>   9
 
                             ILLINOIS POWER COMPANY
 
     Illinois Power was incorporated under the laws of Illinois on May 25, 1923.
Effective May 27, 1994, Illinois Power became a subsidiary of Illinova
Corporation ("Illinova"), an exempt holding company under the Public Utility
Holding Company Act of 1935, as amended, pursuant to a merger in which each
outstanding share of Illinois Power's Common Stock was converted into one share
of common stock of Illinova. Illinois Power is engaged in the generation,
transmission, distribution and sale of electric energy and the distribution and
sale of natural gas in the State of Illinois. Its service area is a widely
diversified industrial and agricultural area comprising approximately 15,000
square miles in northern, central and southern Illinois. Electric service is
provided at retail to 310 incorporated municipalities, adjacent suburban and
rural areas and numerous unincorporated municipalities having an estimated
aggregate population of 1,265,000. Gas service is provided to 257 incorporated
municipalities, adjacent suburban areas and numerous unincorporated
municipalities having an estimated aggregate population of 920,000. The larger
cities served include Decatur, East St. Louis (gas only), Champaign, Danville,
Belleville, Granite City, Bloomington (electric only), Galesburg, Urbana and
Normal (electric only). The executive offices of Illinois Power are located at
500 South 27th Street, Decatur, Illinois 62525, and Illinois Power's telephone
number is (217) 424-6600.
 
                           ILLINOIS POWER FINANCING I
 
   
     Illinois Power Financing I is a statutory business trust formed under
Delaware law pursuant to (i) a declaration of trust, dated as of October 17,
1995, executed by Illinois Power, as sponsor (the "Sponsor"), and the trustees
of Illinois Power Financing I (the "Illinois Power Trustees") and (ii) the
filing of a certificate of trust with the Secretary of State of the State of
Delaware on October 17, 1995. Such declaration will be amended and restated in
its entirety (as so amended and restated, the "Declaration") substantially in
the form filed as an exhibit to the Registration Statement of which this
Prospectus forms a part. The Declaration will be qualified as an indenture under
the Trust Indenture Act. Upon issuance of the Preferred Securities, the
purchasers thereof will own all of the Preferred Securities. See "Description of
the Preferred Securities -- Book-Entry Only Issuance -- The Depository Trust
Company." Illinois Power will directly or indirectly acquire Common Securities
in an aggregate liquidation amount equal to approximately 3% of the total
capital of Illinois Power Financing I. Illinois Power Financing I exists for the
exclusive purposes of (i) issuing the Trust Securities representing undivided
beneficial interests in the assets of Illinois Power Financing I, (ii) investing
the gross proceeds of the Trust Securities in the Subordinated Debentures and
(iii) engaging in only those other activities necessary, convenient or
incidental thereto. Illinois Power Financing I has a term of approximately 55
years, but may terminate earlier as provided in the Declaration.
    
 
     Pursuant to the Declaration, the number of Illinois Power Trustees will
initially be three. Two of the Illinois Power Trustees (the "Regular Trustees")
will be persons who are employees or officers of or who are affiliated with
Illinois Power. The third trustee will be a financial institution that maintains
its principal place of business in the State of Delaware and is unaffiliated
with Illinois Power, which trustee will serve as property trustee under the
Declaration and as indenture trustee for the purposes of compliance with the
provisions of the Trust Indenture Act (the "Property Trustee"). Initially,
Wilmington Trust Company, a Delaware banking corporation, will be the Property
Trustee until removed or replaced by the holder of the Common Securities.
Wilmington Trust Company will also act as indenture trustee under the Guarantee
for the purposes of compliance with the provisions of the Trust Indenture Act
(the "Guarantee Trustee"). See "Description of the Preferred Securities
Guarantee."
 
     The Property Trustee will hold title to the Subordinated Debentures for the
benefit of the holders of the Trust Securities, and the Property Trustee will
have the power to exercise all rights, powers and privileges under the Indenture
(as defined herein) as the holder of the Subordinated Debentures. In addition,
the Property Trustee will maintain exclusive control of a segregated
non-interest bearing bank account (the "Property Account") to hold all payments
made in respect of the Subordinated Debentures for the benefit of the holders of
the Trust Securities. The Property Trustee will make payments of distributions
and payments on liquidation, redemption and otherwise to the holders of the
Trust Securities out of funds from the Property Account. The Guarantee Trustee
will hold the Guarantee for the benefit of the holders of the Preferred
 
                                        8
<PAGE>   10
 
   
Securities. Illinois Power, as the direct or indirect holder of all the Common
Securities, will have the right to appoint, remove or replace any Illinois Power
Trustee and to increase or decrease the number of Illinois Power Trustees;
provided, that (i) the number of Illinois Power Trustees shall be at least
three, and (ii) at least two shall be Regular Trustees. Illinois Power will pay
all fees and expenses related to Illinois Power Financing I and the offering of
the Trust Securities. See "Description of the Subordinated Debentures --
Miscellaneous."
    
 
     The rights of the holders of the Preferred Securities, including rights to
information and voting rights, are set forth in the Declaration, the Delaware
Business Trust Act (the "Trust Act") and the Trust Indenture Act. See
"Description of the Preferred Securities."
 
                                        9
<PAGE>   11
 
                SUMMARY FINANCIAL INFORMATION OF ILLINOIS POWER
                (THOUSANDS EXCEPT PER SHARE AMOUNTS AND RATIOS)
 
     The following information is qualified in its entirety by the information
appearing elsewhere in this Prospectus and by the information and financial
statements incorporated in this Prospectus by reference.
 
   
<TABLE>
<CAPTION>
                                                                                                             12 MONTHS
                                                                                                               ENDED
                                                         YEAR ENDED DECEMBER 31,                           SEPTEMBER 30,
                                    ------------------------------------------------------------------         1995
                                       1990          1991          1992        1993(A)       1994(A)     (UNAUDITED)(A)(B)
                                    ----------    ----------    ----------    ----------    ----------   -----------------
<S>                                 <C>           <C>           <C>           <C>           <C>          <C>
INCOME STATEMENT DATA
Operating Revenues................  $1,469,480    $1,474,905    $1,479,449    $1,581,190    $1,589,465      $ 1,624,032
Net Income (Loss).................     (78,484)      109,244       122,088       (56,038)      180,242          205,357
Preferred Dividend Requirements...      36,839        30,866        28,854        26,123        24,834           25,827
Net Income (Loss) Applicable to
  Common Stock....................    (115,323)       78,378        93,234       (82,161)      161,767(f)        185,889(f)
Ratio of Earnings to Fixed
  Charges(c)......................        0.70(d)       1.85          2.02          0.80(d)       2.75             2.92
Ratio of Earnings to Combined
  Fixed Charges and Preferred
  Stock Dividend
  Requirements(c).................        0.60(e)       1.48          1.61          0.70(e)       2.21             2.40
</TABLE>
    
 
   
<TABLE>
<CAPTION>
                                                                                         AT SEPTEMBER 30, 1995
                                                                                       -------------------------
                                                                                         ACTUAL      AS ADJUSTED
                                                                                       ----------    -----------
                                                                                                     (UNAUDITED)
<S>                                                                                    <C>           <C>
CAPITALIZATION
Long-Term Debt......................................................................   $1,738,664    $1,738,664
Preferred Stock (not subject to mandatory redemption)...............................      221,512       121,512
Company-obligated Mandatorily Redeemable Preferred Securities of Illinois Power
  Capital, L.P.(g) .................................................................       97,000        97,000
Company-obligated Mandatorily Redeemable Preferred Securities of Illinois Power
  Financing I(h)....................................................................           --       100,000
Common Stock Equity.................................................................    1,516,921     1,516,921
                                                                                       ----------    ----------
    Total Capitalization............................................................   $3,574,097    $3,574,097
                                                                                       ==========    ==========
</TABLE>
    
 
- -------------------------
(a) Subsequent to Illinois Power's merger with Illinova, net assets of Illinova
    Generating Company (formerly IP Group, Inc.) were transferred in the form of
    a dividend from the Company to Illinova. The income statement data contained
    herein has been restated to reflect the financial results of Illinois
    Power's current operations.
 
   
(b) In the opinion of Illinois Power, all adjustments, consisting only of normal
    recurring adjustments, necessary for a fair statement of the results for the
    unaudited twelve-month period ended September 30, 1995, have been made.
    
 
(c) Earnings used in the calculation of the ratio of earnings to fixed charges
    and the ratio of earnings to combined fixed charges and preferred stock
    dividend requirements include the allowance for funds used during
    construction and the deferred financing costs associated with Illinois
    Power's Clinton Power Station and are before deduction of income taxes and
    fixed charges. Fixed charges include interest on long-term debt, related
    amortization of debt discount, premium, and expense, other interest and that
    portion of rent expense which is estimated to be representative of the
    interest component. Preferred stock dividend requirements have been
    increased to an amount representing the pre-tax earnings required to cover
    such dividend requirements.
 
(d) The ratios of earnings to fixed charges for the years ended December 31,
    1993 and 1990 of 0.80 and 0.70, respectively, indicate that earnings were
    inadequate to cover fixed charges. The dollar amounts of the coverage
    deficiency for the years ended 1993 and 1990 were approximately $37 million
    and $68 million, respectively. Excluding the loss on disallowed plant costs
    of $200 million, net of income taxes, recorded in the third quarter of 1993,
    the ratio of earnings to fixed charges would have been 2.25 for the year
    ended 1993. Excluding the loss on disallowed plant costs of $137 million,
    net of income taxes, recorded in the fourth quarter of 1990, the ratio of
    earnings to fixed charges would have been 1.41 for the year ended 1990.
 
(e) The ratios of earnings to combined fixed charges and preferred stock
    dividend requirements for the years ended December 31, 1993 and 1990 of 0.70
    and 0.60, respectively, indicate that earnings were inadequate to cover
    combined fixed charges and preferred stock dividend requirements. The dollar
    amounts of the coverage deficiency for the years ended 1993 and 1990 were
    approximately $63 million and $105 million, respectively. Excluding the loss
    on disallowed plant costs of $200 million, net of income taxes, recorded in
    the third quarter of 1993, the ratio of earnings to combined fixed charges
    and preferred stock dividend requirements would have been 1.83 for the year
    ended 1993. Excluding the loss on disallowed plant costs of $137 million,
    net of income taxes, recorded in the fourth quarter of 1990, the ratio of
    earnings to combined fixed charges and preferred stock dividend requirements
    would have been 1.09 for the year ended 1990.
 
(f) Includes $6 million excess of carrying amount over consideration paid for
    redeemed preferred stock.
 
   
(g) The sole asset of Illinois Power Capital, L.P. is the $100 million principal
    amount of 9.45% Subordinated Deferrable Interest Debentures due 2043 of
    Illinois Power.
    
 
   
(h) As described in this Prospectus, the sole asset of Illinois Power Financing
    I will be the $103.1 million principal amount of Subordinated Debentures of
    Illinois Power.
    
 
                                       10
<PAGE>   12
 
                              ACCOUNTING TREATMENT
 
     The financial statements of Illinois Power Financing I will be reflected in
Illinois Power's consolidated financial statements with the Preferred Securities
shown as Company-obligated mandatorily redeemable preferred securities of
Illinois Power Financing I holding subordinated debentures of Illinois Power.
 
                                USE OF PROCEEDS
 
     All of the proceeds from the sale of the Preferred Securities will be
invested by Illinois Power Financing I in Subordinated Debentures of Illinois
Power issued pursuant to the Indenture therefor described herein and ultimately
will be used by Illinois Power to purchase or redeem outstanding shares of
preferred stock of Illinois Power, and for general corporate purposes.
 
                    DESCRIPTION OF THE PREFERRED SECURITIES
 
     The Preferred Securities will be issued pursuant to the terms of the
Declaration. The Declaration will be qualified as an indenture under the Trust
Indenture Act. The Property Trustee, Wilmington Trust Company, will act as
indenture trustee under the Declaration for purposes of compliance with the
provisions of the Trust Indenture Act. The terms of the Preferred Securities
will include those stated in the Declaration and those made part of the
Declaration 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
Declaration (a copy of which is filed as an exhibit to the Registration
Statement of which this Prospectus is a part) and the Trust Indenture Act.
 
GENERAL
 
   
     The Declaration authorizes the Regular Trustees to issue on behalf of
Illinois Power Financing I the Trust Securities, which represent undivided
beneficial interests in the assets of Illinois Power Financing I. All of the
Common Securities will be owned, directly or indirectly, by Illinois Power. The
Common Securities rank pari passu, and payments will be made thereon on a pro
rata basis, with the Preferred Securities, except that upon the occurrence of a
Declaration Event of Default, 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 Declaration does not permit the issuance by
Illinois Power Financing I of any securities other than the Trust Securities or
the incurrence of any indebtedness by Illinois Power Financing I. Pursuant to
the Declaration, the Property Trustee will own the Subordinated Debentures
purchased by Illinois Power Financing I for the benefit of the holders of the
Trust Securities. The payment of distributions out of money held by Illinois
Power Financing I, and payments upon redemption of the Trust Securities or
termination of Illinois Power Financing I, are guaranteed by Illinois Power to
the extent described under "Description of the Preferred Securities Guarantee."
The Guarantee will be held by Wilmington Trust Company, the Guarantee Trustee,
for the benefit of the holders of the Preferred Securities. The Guarantee does
not cover payment of distributions when Illinois Power Financing I does not have
sufficient available funds to pay such distributions. In such event, the remedy
of a holder of Preferred Securities is to vote to direct the Property Trustee to
enforce the Property Trustees rights under the Subordinated Debentures. See
"Description of the Preferred Securities -- Voting Rights."
    
 
DISTRIBUTIONS
 
     Distributions on the Preferred Securities will be fixed at a rate per annum
of   % of the stated liquidation amount of $25 per Preferred Security.
Distributions in arrears for more than one quarter will bear interest thereon at
the rate per annum of   % thereof compounded quarterly. The term "distribution"
as used herein includes any such interest payable unless otherwise stated. The
amount of distributions payable for any period will be computed on the basis of
a 360-day year of twelve 30-day months.
 
                                       11
<PAGE>   13
 
     Distributions on the Preferred Securities will be cumulative, will accrue
from                , 1995, and will be payable quarterly in arrears on March
31, June 30, September 30, and December 31 of each year, commencing December 31,
1995, when, as and if funds are available and determined to be so payable by the
Property Trustee, except as otherwise described below.
 
   
     Illinois Power has the right under the Indenture to defer payments of
interest on the Subordinated Debentures by extending the interest payment period
from time to time on the Subordinated Debentures, which, if exercised, would
defer quarterly distributions on the Preferred Securities (though such
distributions would continue to accrue with interest since interest would
continue to accrue on the Subordinated Debentures) during any such Extension
Period. Such right to extend the interest payment period for the Subordinated
Debentures is limited to a period not exceeding 20 consecutive quarters provided
that no Extension Period shall last beyond the date of maturity of the
Subordinated Debentures. In the event that Illinois Power exercises this right,
then (a) Illinois Power shall not declare or pay dividends on, make
distributions with respect to, or redeem, purchase or acquire, or make a
liquidation payment with respect to, any of its capital stock, and (b) Illinois
Power shall not make any payment of interest, principal or premium, if any, on
or repay, repurchase or redeem any debt securities issued by Illinois Power that
rank pari passu with or junior to such Subordinated Debentures. Prior to the
termination of any such Extension Period, Illinois Power may further extend the
interest payment period; provided, that such Extension Period, together with all
such previous and further extensions thereof, may not exceed 20 consecutive
quarters or extend beyond the maturity date of the Subordinated Debentures. Upon
the termination of any Extension Period and the payment of all amounts then due,
Illinois Power may select a new Extension Period, subject to the above
requirements. See "Description of the Subordinated Debentures -- Interest" and
"-- Option to Extend Interest Payment Period." If distributions are deferred,
the deferred distributions and accrued interest thereon shall be paid to holders
of record of the Preferred Securities as they appear on the books and records of
Illinois Power Financing I on the record date next following the termination of
such deferral period.
    
 
     Distributions on the Preferred Securities must be paid on the dates payable
to the extent that Illinois Power Financing I has funds available for the
payment of such distributions in the Property Account. Illinois Power Financing
I's funds available for distribution to the holders of the Preferred Securities
will be limited to payments received from Illinois Power on the Subordinated
Debentures. See "Description of the Subordinated Debentures." The payment of
distributions out of moneys held by Illinois Power Financing I is guaranteed by
Illinois Power to the extent set forth under "Description of the Preferred
Securities Guarantee."
 
     Distributions on the Preferred Securities will be payable to the holders
thereof as they appear on the books and records of Illinois Power Financing I on
the relevant record dates, which, as long as the Preferred Securities remain in
book-entry only form, will be one Business Day (as defined herein) prior to the
relevant payment dates. Such distributions will be paid through the Property
Trustee who will hold amounts received in respect of the Subordinated Debentures
in the Property Account for the benefit of the holders of the Trust Securities.
Subject to any applicable laws and regulations and the provisions of the
Declaration, each such payment will be made as described under "Book-Entry Only
Issuance -- The Depository Trust Company" below. In the event that the Preferred
Securities do not continue to remain in book-entry only form, the relevant
record dates for the Preferred Securities shall conform to the rules of any
securities exchange on which the securities are listed and, if none, shall be
selected by the Regular Trustees, which dates shall be at least one Business Day
but less than 60 Business Days prior to the relevant payment dates. 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 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 such date. A "Business Day" shall mean any day other than
Saturday, Sunday or any other day on which banking institutions in New York City
(in the State of New York) are permitted or required by any applicable law to
close.
 
MANDATORY REDEMPTION
 
     The Subordinated Debentures will mature on           , 2044, and may be
redeemed, in whole or in part, at any time on or after           , 2000, or at
any time in certain circumstances upon the occurrence of a Tax
 
                                       12
<PAGE>   14
 
Event (as defined herein). Upon the repayment of the Subordinated Debentures,
whether at maturity or upon redemption, the proceeds from such repayment or
payment shall simultaneously be applied to redeem Trust Securities having an
aggregate liquidation amount equal to the aggregate principal amount of the
Subordinated Debentures so repaid or redeemed at the Redemption Price; provided,
that holders of Trust Securities shall be given not less than 30 nor more than
60 days notice of such redemption, except in the case of payments upon maturity.
See "Description of the Subordinated Debentures -- Optional Redemption." In the
event that fewer than all of the outstanding Preferred Securities are to be
redeemed, the Preferred Securities will be redeemed pro rata as described under
"Book -- Entry Only Issuance -- The Depository Trust Company" below.
 
SPECIAL EVENT REDEMPTION OR DISTRIBUTION
 
     "Tax Event" means that the Regular Trustees shall have received an opinion
of a nationally recognized independent tax counsel experienced in such matters
(a "Dissolution Tax Opinion") to the effect that, as a result of (a) 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 (b) any amendment to or
change in an interpretation or application of such laws or regulations by any
legislative body, court, governmental agency or regulatory authority, in each
case on or after the date of this Prospectus, there is more than an
insubstantial risk that (i) Illinois Power Financing I is or within 90 days will
be subject to United States federal income tax with respect to income accrued or
received on the Subordinated Debentures, (ii) interest payable to Illinois Power
Financing I on the Subordinated Debentures is or within 90 days will not be
deductible by Illinois Power for United States federal income tax purposes or
(iii) Illinois Power Financing I is or within 90 days will be subject to more
than a de minimis amount of other taxes, duties or other governmental charges,
which change or amendment becomes effective on or after the date of this
Prospectus.
 
     "Investment Company Event" means that the Regular Trustees shall have
received an opinion from independent counsel experienced in practice under the
1940 Act (as defined herein) to the effect that, as a result of the occurrence
of a change in law or regulation or a written change in interpretation or
application of law or regulation by any legislative body, court, governmental
agency or regulatory authority (a "Change in 1940 Act Law"), there is more than
an insubstantial risk that Illinois Power Financing I is or will be considered
an "investment company" which is required to be registered under the Investment
Company Act of 1940, as amended (the "1940 Act"), which Change in 1940 Act Law
becomes effective on or after the date of this Prospectus.
 
     If, at any time, a Tax Event or an Investment Company Event (each, as
defined above, a "Special Event"), shall occur and be continuing, Illinois Power
Financing I shall, except in the limited circumstances described below, be
terminated with the result that, after satisfaction of liabilities to creditors,
the Subordinated Debentures with an aggregate principal amount equal to the
aggregate stated liquidation amount of, with an interest rate identical to the
distribution rate of, and accrued and unpaid interest equal to accrued and
unpaid distributions on, the Trust Securities, would be distributed to the
holders of the Trust Securities in liquidation of such holders' interests in
Illinois Power Financing I on a pro rata basis within 90 days following the
occurrence of such Special Event; provided, however, that in the case of the
occurrence of a Tax Event, that such termination and distribution shall be
conditioned on (i) the Regular Trustees' receipt of an opinion of nationally
recognized independent tax counsel experienced in such matters (a "No
Recognition Opinion"), which opinion may rely on published revenue rulings of
the Internal Revenue Service, to the effect that the holders of the Trust
Securities will not recognize any gain or loss for United States federal income
tax purposes as a result of such termination of Illinois Power Financing I and
such distribution of Subordinated Debentures and (ii) Illinois Power being
unable to avoid such Tax Event within such 90-day period by taking some
ministerial action or pursuing some other reasonable measure that will have no
adverse effect on Illinois Power Financing I, Illinois Power or the holders of
the Trust Securities. Furthermore, if after receipt of a Dissolution Tax Opinion
by the Regular Trustees (i) Illinois Power has received an opinion (a
"Redemption Tax Opinion") of nationally recognized independent tax counsel
experienced in such matters that, as a result of a Tax Event, there is more than
an insubstantial risk that Illinois Power would be precluded from deducting
 
                                       13
<PAGE>   15
 
the interest on the Subordinated Debentures for United States federal income tax
purposes, even after the Subordinated Debentures were distributed to the holders
of Trust Securities in liquidation of such holders' interests in Illinois Power
Financing I as described above, or (ii) the Regular Trustees shall have been
informed by such tax counsel that it cannot deliver a No Recognition Opinion to
Illinois Power Financing I, Illinois Power shall have the right, upon not less
than 30 nor more than 60 days notice, to redeem the Subordinated Debentures, in
whole or in part, for cash within 90 days following the occurrence of such Tax
Event, and, following such redemption, Trust Securities with an aggregate
liquidation amount equal to the aggregate principal amount of the Subordinated
Debentures so redeemed shall be redeemed by Illinois Power Financing I at the
Redemption Price on a pro rata basis; provided, however, that if at the time
there is available to Illinois Power or Illinois Power Financing I the
opportunity to eliminate, within such 90-day period, the Tax Event by taking
some ministerial action, such as filing a form or making an election or pursuing
some other similar reasonable measure that has no adverse effect on Illinois
Power Financing I, Illinois Power or the holders of the Trust Securities,
Illinois Power or Illinois Power Financing I will pursue such measure in lieu of
redemption.
 
     If the Subordinated Debentures are distributed to the holders of the
Preferred Securities, Illinois Power will use its best efforts to cause the
Subordinated Debentures to be 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 Subordinated Debentures upon
termination of Illinois Power Financing I, (i) the Preferred Securities will no
longer be deemed to be outstanding, (ii) the Depositary (as defined herein) or
its nominee, as the record holder of the Preferred Securities, will receive a
registered global certificate or certificates representing the Subordinated
Debentures to be delivered upon such distribution, and (iii) any certificates
representing Preferred Securities not held by the Depositary or its nominee will
be deemed to represent beneficial interests in the Subordinated Debentures
having an aggregate principal amount equal to the aggregate stated liquidation
amount of, with an interest rate identical to the distribution rate of, and
accrued and unpaid interest equal to accrued and unpaid distributions on such
Preferred Securities until such certificates are presented to Illinois Power or
its agent for transfer or reissuance.
    
 
     There can be no assurance as to the market prices for either the Preferred
Securities or the Subordinated Debentures that may be distributed in exchange
for the Preferred Securities if a termination of Illinois Power Financing I were
to occur. Accordingly, the Preferred Securities that an investor may purchase,
whether pursuant to the offer made hereby or in the secondary market, or the
Subordinated Debentures that an investor may receive if a termination of
Illinois Power Financing I were to occur, may trade at a discount to the price
that the investor paid to purchase the Preferred Securities offered hereby.
 
REDEMPTION PROCEDURES
 
     Illinois Power Financing I may not redeem fewer than all of the outstanding
Preferred Securities unless all accrued and unpaid distributions have been paid
on all Preferred Securities for all quarterly distribution periods terminating
on or prior to the date of redemption.
 
   
     If Illinois Power Financing I gives a notice of redemption in respect of
Preferred Securities (which notice will be irrevocable), then, by 12:00 noon,
New York City time, on the redemption date, provided that Illinois Power has
paid to the Property Trustee a sufficient amount of cash in connection with the
related redemption or maturity of the Subordinated Debentures, Illinois Power
Financing I will irrevocably deposit with the Depositary funds sufficient to pay
the applicable Redemption Price and will give the Depositary irrevocable
instructions and authority to pay the Redemption Price to the holders of the
Preferred Securities. See "Book-Entry Only Issuance -- The Depository Trust
Company." If notice of redemption shall have been given and funds deposited as
required, then, immediately prior to the close of business on the date of such
deposit, distributions will cease to accrue and all rights of holders of such
Preferred Securities so called for redemption will cease, except the right of
the holders of such Preferred Securities to receive the Redemption Price but
without interest on such Redemption Price. In the event that any date fixed for
redemption of Preferred Securities 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 (without any interest or other payment in respect of any
such
    
 
                                       14
<PAGE>   16
 
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 the event
that payment of the Redemption Price in respect of Preferred Securities is
improperly withheld or refused and not paid either by Illinois Power Financing
I, or by Illinois Power pursuant to the Guarantee, distributions on such
Preferred Securities will continue to accrue at the then applicable rate from
the original redemption date to the date of payment, in which case the actual
payment date will be considered the date fixed for redemption for purposes of
calculating the Redemption Price.
 
     In the event that fewer than all of the outstanding Preferred Securities
are to be redeemed, the Preferred Securities will be redeemed pro rata as
described below under "Book-Entry Only Issuance -- The Depository Trust
Company."
 
     Subject to the foregoing and applicable law (including, without limitation,
United States federal securities laws), Illinois Power or 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.
 
LIQUIDATION DISTRIBUTION UPON TERMINATION
 
     In the event of any voluntary or involuntary dissolution, winding-up or
termination of Illinois Power Financing I (each, a "Liquidation"), then holders
of the Preferred Securities will be entitled to receive out of the assets of
Illinois Power Financing I, after satisfaction of liabilities to creditors,
distributions in an amount equal to the aggregate of the stated liquidation
amount of $25 per Preferred Security plus accrued and unpaid distributions
thereon to the date of payment (the "Liquidation Distribution"), unless, in
connection with such Liquidation, Subordinated Debentures in an aggregate
principal amount equal to the aggregate stated liquidation amount of, with an
interest rate identical to the distribution rate of, and accrued and unpaid
interest equal to accrued and unpaid distributions on, the Preferred Securities
have been distributed on a pro rata basis to the holders of the Preferred
Securities in exchange for such Preferred Securities.
 
     If, upon any such Liquidation, the Liquidation Distribution can be paid
only in part because Illinois Power Financing I has insufficient assets
available to pay in full the aggregate Liquidation Distribution, then the
amounts payable directly by Illinois Power Financing I on the Preferred
Securities shall be paid on a pro rata basis. The holders of the Common
Securities will be entitled to receive distributions upon any such Liquidation
pro rata with the holders of the Preferred Securities, except that if a
Declaration Event of Default has occurred and is continuing, the Preferred
Securities shall have a preference over the Common Securities with regard to
such distributions.
 
     Pursuant to the Declaration, Illinois Power Financing I shall terminate (i)
on December 31, 2050, the expiration of the term of Illinois Power Financing I,
(ii) upon the bankruptcy of Illinois Power or the holder of the Common
Securities, (iii) upon the filing of a certificate of dissolution or its
equivalent with respect to the holder of the Common Securities or Illinois
Power, or the revocation of the charter of the holder of the Common Securities
or Illinois Power and the expiration of 90 days after the date of revocation
without a reinstatement thereof, (iv) upon the distribution of Subordinated
Debentures upon the occurrence of a Special Event, (v) upon the entry of a
decree of a judicial dissolution of the holder of the Common Securities,
Illinois Power or Illinois Power Financing I, or (vi) upon the redemption of all
the Trust Securities.
 
DECLARATION EVENTS OF DEFAULT
 
     An event of default under the Indenture (an "Indenture Event of Default")
constitutes an event of default under the Declaration with respect to the Trust
Securities (a "Declaration Event of Default"); provided, that pursuant to the
Declaration, the holder of the Common Securities will be deemed to have waived
any Declaration Event of Default with respect to the Common Securities until all
Declaration Events of Default with respect to the Preferred Securities have been
cured, waived or otherwise eliminated. Until such Declaration Events of Default
with respect to the Preferred Securities have been so cured, waived, or
otherwise eliminated, the Property Trustee will be deemed to be acting solely on
behalf of the holders of the Preferred Securities and only the holders of the
Preferred Securities will have the right to direct the Property Trustee with
respect to certain matters under the Declaration, and therefore the Indenture.
 
                                       15
<PAGE>   17
 
     Upon the occurrence of a Declaration Event of Default, the Property
Trustee, as the sole holder of the Subordinated Debentures, will have the right
under the Indenture to declare the principal of and interest on the Subordinated
Debentures to be immediately due and payable. Illinois Power and Illinois Power
Financing I are each required to file annually with the Property Trustee an
officer's certificate as to its compliance with all conditions and covenants
under the Declaration.
 
VOTING RIGHTS
 
     Except as described herein under "Description of the Preferred Securities
Guarantee -- Amendments and Assignment" and as otherwise required by law and the
Declaration, the holders of the Preferred Securities will have no voting rights.
In the event that Illinois Power elects to defer payments of interest on the
Subordinated Debentures as described above under "-- Distributions," the holders
of the Preferred Securities do not have the right to appoint a special
representative or trustee or otherwise act to protect their interests.
 
     Subject to the requirement of the Property Trustee obtaining a tax opinion
in certain circumstances set forth in the last sentence of this paragraph, the
holders of a majority in aggregate liquidation amount of the Preferred
Securities have the right to direct the time, method and place of conducting any
proceeding for any remedy available to the Property Trustee, or direct the
exercise of any trust or power conferred upon the Property Trustee under the
Declaration including the right to direct the Property Trustee, as holder of the
Subordinated Debentures, to (i) exercise the remedies available under the
Indenture with respect to the Subordinated Debentures, (ii) waive any past
Indenture Event of Default that is waivable under the Base Indenture (as defined
herein), (iii) exercise any right to rescind or annul a declaration that the
principal of all the Subordinated Debentures shall be due and payable, provided,
however, that, where a consent or action under the Indenture would require the
consent or act of holders of more than a majority in principal amount of the
Subordinated Debentures (a "Super-Majority") affected thereby, only the holders
of at least the proportion in liquidation amount of the Preferred Securities
which the relevant Super-Majority represents of the aggregate principal amount
of the Subordinated Debentures may direct the Property Trustee to give such
consent or take such action. If the Property Trustee fails to enforce its rights
under the Subordinated Debentures or the Declaration to the fullest extent
permitted by law, a record holder of Preferred Securities may, after such
holder's written request to the Property Trustee to enforce such rights,
institute a legal proceeding directly against Illinois Power to enforce the
Property Trustee's rights under the Subordinated Debentures or the Declaration
without first instituting any legal proceeding against the Property Trustee or
any other person or entity. 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 Subordinated Debentures. Such notice shall state
that such Indenture Event of Default also constitutes a Declaration Event of
Default. Except with respect to directing the time, method and place of
conducting a proceeding for a remedy, the Property Trustee shall not take any of
the actions described in clauses (i), (ii) or (iii) above unless the Property
Trustee has obtained an opinion of tax counsel to the effect that, as a result
of such action, Illinois Power Financing I will not fail to be classified as a
grantor trust for United States federal income tax purposes and that each holder
of Preferred Securities will not fail to be treated as owning an undivided
beneficial interest in the Subordinated Debentures.
 
     In the event the consent of the Property Trustee, as the holder of the
Subordinated Debentures, is required under the Indenture with respect to any
amendment, modification or termination of the Indenture, the Property Trustee
shall request the direction of the holders of the Trust Securities with respect
to such amendment, modification or termination and shall vote with respect to
such amendment, modification or termination as directed by 66 2/3% in
liquidation amount of the Trust Securities voting together as a single class;
provided, however, that where a consent under the Indenture would require the
consent of a Super-Majority, the Property Trustee may only give such consent at
the direction of the holders of at least the proportion in liquidation amount of
the Trust Securities which the relevant Super-Majority represents of the
aggregate principal amount of the Subordinated Debentures outstanding. The
Property Trustee shall be under no obligation to take any such action in
accordance with the directions of the holders of the Trust Securities unless the
Property Trustee has obtained an opinion of tax counsel to the affect that for
the purposes of United States federal income tax Illinois Power Financing I will
not be classified as other than a grantor trust and that
 
                                       16
<PAGE>   18
 
each holder of Preferred Securities will not fail to be treated as owning an
undivided beneficial interest in the Subordinated Debentures.
 
     A waiver of an Indenture Event of Default will constitute a waiver of the
corresponding Declaration Event of Default.
 
     Any required approval or direction of holders of Preferred Securities may
be given at a separate meeting of holders of Preferred Securities convened for
such purpose, at a meeting of all of the holders of Trust Securities or pursuant
to written consent. The Regular Trustees will cause a notice of any meeting at
which holders of Preferred Securities are entitled to vote, or of any matter
upon which action by written consent of such holders is to be taken, to be
mailed to each holder of record of Preferred Securities. Each such notice will
include a statement setting forth the following information: (i) the date of
such meeting or the date by which such action is to be taken; (ii) a description
of any resolution proposed for adoption at such meeting on which such holders
are entitled to vote or of such matter upon which written consent is sought; and
(iii) instructions for the delivery of proxies or consents. No vote or consent
of the holders of Preferred Securities will be required for Illinois Power
Financing I to redeem and cancel Preferred Securities or distribute Subordinated
Debentures in accordance with the Declaration.
 
     Notwithstanding that holders of Preferred Securities are entitled to vote
or consent under any of the circumstances described above, any of the Preferred
Securities that are owned at such time by Illinois Power or any entity directly
or indirectly controlling or controlled by, or under direct or indirect common
control with, Illinois Power, shall not be entitled to vote or consent and
shall, for purposes of such vote or consent, be treated as if such Preferred
Securities were not outstanding.
 
     The procedures by which holders of Preferred Securities may exercise their
voting rights are described below. See "-- Book-Entry Only Issuance -- The
Depository Trust Company" below.
 
     Holders of the Preferred Securities will have no rights to appoint or
remove the Illinois Power Trustees, who may be appointed, removed or replaced
solely by Illinois Power as the indirect or direct holder of all of the Common
Securities.
 
MODIFICATION OF THE DECLARATION
 
   
     The Declaration may be modified and amended if approved by the Regular
Trustees (and in certain circumstances the Property Trustee or the Delaware
Trustee), provided that, if any proposed amendment provides for, or the Regular
Trustees otherwise propose to effect, (i) any action that would materially
adversely affect the powers, preferences or special rights of the holders of
Trust Securities, whether by way of amendment to the Declaration or otherwise or
(ii) the dissolution, winding-up or termination of Illinois Power Financing I
other than pursuant to the terms of the Declaration, then the holders of the
Trust Securities voting together as a single 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 at least 66 2/3% in liquidation amount of the Trust
Securities affected thereby; provided, that, if any amendment or proposal
referred to in clause (i) above would materially adversely affect only the
Preferred Securities or the Common Securities, then only the affected 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 66 2/3% in liquidation amount
of such class of Securities.
    
 
     Notwithstanding the foregoing, no amendment or modification may be made to
the Declaration if such amendment or modification would (i) cause Illinois Power
Financing I to be classified for purposes of United States federal income
taxation as other than a grantor trust, (ii) reduce or otherwise materially
adversely affect the powers of the Property Trustee or the Delaware Trustee or
(iii) cause Illinois Power Financing I to be deemed an "investment company"
which is required to be registered under the 1940 Act.
 
MERGERS, CONSOLIDATIONS OR AMALGAMATIONS
 
     Illinois Power Financing 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. Illinois Power Financing I may, with the consent of the Regular
Trustees and
 
                                       17
<PAGE>   19
 
   
without the consent of the holders of the Trust Securities, consolidate,
amalgamate, merge with or into, or be replaced by a trust organized as such
under the laws of any State; provided, that (i) such successor entity either (x)
expressly assumes all of the obligations of Illinois Power Financing I under the
Trust Securities or (y) substitutes for the Preferred Securities other
securities having substantially the same terms as the Trust Securities (the
"Successor Securities"), so long as the Successor Securities rank the same as
the Trust Securities rank with respect to distributions and payments upon
liquidation, redemption and otherwise, (ii) Illinois Power expressly
acknowledges a trustee of such successor entity possessing the same powers and
duties as the Property Trustee as the holder of the Subordinated Debentures,
(iii) the Preferred Securities or any Successor Securities are listed, or any
Successor Securities will be listed upon notification of issuance, on any
national securities exchange or with another organization on which the Preferred
Securities are then listed or quoted, (iv) such merger, consolidation,
amalgamation or replacement 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 or
replacement does not adversely affect the rights, preferences and privileges of
the holders of the Trust Securities (including any Successor Securities) in any
material respect (other than with respect to any dilution of the holders'
interest in the new entity), (vi) such successor entity has a purpose identical
to that of Illinois Power Financing I, (vii) prior to such merger,
consolidation, amalgamation or replacement, Illinois Power has received an
opinion of a nationally recognized independent counsel to Illinois Power
Financing I experienced in such matters to the effect that, (A) such merger,
consolidation, amalgamation or replacement does not adversely affect the rights,
preferences and privileges of the holders of the Trust Securities (including any
Successor Securities) in any material respect (other than with respect to any
dilution of the holders' interest in the new entity), (B) following such merger,
consolidation, amalgamation or replacement, neither Illinois Power Financing I
nor such successor entity will be required to register as an investment company
under the 1940 Act and (C) following such merger, consolidation, amalgamation or
replacement, Illinois Power Financing I (or the Successor Entity) will continue
to be classified as a grantor trust for United States federal income tax
purposes, and each holder of the Trust Securities will be treated as owning an
undivided beneficial interest in the Subordinated Debentures, and (viii)
Illinois Power guarantees the obligations of such successor entity under the
Successor Securities at least to the extent provided by the Guarantee and the
Common Securities Guarantee. Notwithstanding the foregoing, Illinois Power
Financing I shall not, except with the consent of holders of 100% in liquidation
amount of the Trust Securities, consolidate, amalgamate, merge with or into, or
be replaced by any other entity or permit any other entity to consolidate,
amalgamate, merge with or into, or replace it, if such consolidation,
amalgamation, merger or replacement would cause Illinois Power Financing I or
the successor entity to be classified as other than a grantor trust for United
States federal income tax purposes.
    
 
BOOK-ENTRY ONLY ISSUANCE -- THE DEPOSITORY TRUST COMPANY
 
     The Depository Trust Company ("DTC") will act as 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,
representing the total aggregate number of Preferred Securities, will be issued
and will be deposited with DTC.
 
     The laws of some jurisdictions require that certain purchasers of
securities take physical delivery of securities in definitive form. Such laws
may impair the ability to transfer beneficial interests in the global Preferred
Securities as represented by a global certificate.
 
     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 Exchange Act. 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
 
                                       18
<PAGE>   20
 
corporations and certain 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
transactions through or maintain a direct or indirect 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 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
each Preferred Security ("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 the Preferred Securities, except in the event that
use of the book-entry system for the Preferred Securities is discontinued.
 
     To facilitate subsequent transfers, all the Preferred Securities deposited
by Participants with DTC are registered in the name of DTC's nominee, Cede & Co.
The deposit of Preferred Securities with DTC and their registration in the name
of Cede & Co. effect no change in beneficial ownership. 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
that may be in effect from time to time.
 
     Redemption notices shall be sent to Cede & Co. If less than all of the
Preferred Securities are being redeemed, DTC will reduce the amount of the
interest of each Direct Participant in such Preferred Securities in accordance
with its procedures.
 
     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 Preferred Securities. Under its usual
procedures, DTC would mail an Omnibus Proxy to Illinois Power Financing I as
soon as possible after the record date. The Omnibus Proxy assigns Cede & Co.
consenting or voting rights to those Direct Participants to whose accounts the
Preferred Securities are credited on the record date (identified in a listing
attached to the Omnibus Proxy). Illinois Power and Illinois Power Financing I
believe that the arrangements among DTC, Direct and Indirect Participants, and
Beneficial Owners will enable the Beneficial Owners to exercise rights
equivalent in substance to the rights that can be directly exercised by a holder
of a beneficial interest in Illinois Power Financing I.
 
     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 such
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 in bearer form or registered in "street name,"
and such payments will be the responsibility of such Participant and not of DTC,
Illinois Power Financing I or Illinois Power, subject to any statutory or
regulatory requirements to the contrary that may be in effect from time to time.
Payment of distributions to DTC is the responsibility of Illinois Power
Financing 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.
 
                                       19
<PAGE>   21
 
     Except as provided herein, a Beneficial Owner 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.
 
     DTC may discontinue providing its services as securities depositary with
respect to the Preferred Securities at any time by giving reasonable notice to
Illinois Power Financing I. Under such circumstances, in the event that a
successor securities depositary is not obtained, Preferred Securities
certificates are required to be printed and delivered. Additionally, the Regular
Trustees (with the consent of Illinois Power) may decide to discontinue use of
the system of book-entry transfers through DTC (or any successor depositary)
with respect to the Preferred Securities. In that event, certificates for the
Preferred Securities will be printed and delivered.
 
     The information in this section concerning DTC and DTC's book-entry system
has been obtained from sources that Illinois Power and Illinois Power Financing
I believe to be reliable, but neither Illinois Power nor Illinois Power
Financing I takes responsibility for the accuracy thereof.
 
INFORMATION CONCERNING THE PROPERTY TRUSTEE
 
     The Property Trustee, prior to the occurrence of a default with respect to
the Trust Securities, undertakes to perform only such duties as are specifically
set forth in the Declaration and, after default, shall 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 Property Trustee is under no obligation
to exercise any of the powers vested in it by the Declaration at the request of
any holder of Preferred Securities, unless offered reasonable indemnity by such
holder against the costs, expenses and liabilities which might be incurred
thereby. The holders of Preferred Securities will not be required to offer such
indemnity in the event such holders, by exercising their voting rights, direct
the Property Trustee to take any action following a Declaration Event of
Default.
 
PAYING AGENT
 
     In the event that the Preferred Securities do not remain in book-entry only
form, the following provisions would apply:
 
     The Property Trustee will act as paying agent and may designate an
additional or substitute paying agent at any time.
 
     Registration of transfers of Preferred Securities will be effected without
charge by or on behalf of Illinois Power Financing I, but upon payment (with the
giving of such indemnity as the Regular Trustees may require) in respect of any
tax or other governmental charges that may be imposed in relation to it.
 
     Illinois Power Financing I will not be required to register or cause to be
registered the transfer of Preferred Securities after such Preferred Securities
have been called for redemption.
 
GOVERNING LAW
 
     The Declaration and the Preferred Securities will be governed by, and
construed in accordance with, the internal laws of the State of Delaware.
 
MISCELLANEOUS
 
     The Regular Trustees are authorized and directed to operate Illinois Power
Financing I in such a way so that Illinois Power Financing I will not be
required to register as an "investment company" under the 1940 Act or
characterized as other than a grantor trust for United States federal income tax
purposes and so that each holder of Preferred Securities will be treated as
owning an undivided beneficial interest in the Subordinated Debentures. Illinois
Power is authorized and directed to conduct its affairs so that the Subordinated
Debentures will be treated as indebtedness of Illinois Power for United States
federal income tax purposes. In this connection, Illinois Power and the Regular
Trustees are authorized to take any action, not inconsistent with applicable
law, the certificate of trust of Illinois Power Financing I or the certificate
of
 
                                       20
<PAGE>   22
 
incorporation of Illinois Power, that each of Illinois Power and the Regular
Trustees determine in their discretion to be necessary or desirable to achieve
such end, as long as such action does not materially adversely affect the
interests of the holders of the Preferred Securities or vary the terms thereof.
 
     Holders of the Preferred Securities have no preemptive rights.
 
               DESCRIPTION OF THE PREFERRED SECURITIES GUARANTEE
 
     Set forth below is a summary of information concerning the Guarantee that
will be executed and delivered by Illinois Power for the benefit of the holders
from time to time of the Preferred Securities. The Guarantee will be qualified
as an indenture under the Trust Indenture Act. Wilmington Trust Company will act
as the Guarantee Trustee. The terms of the Guarantee 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 Guarantee,
which is filed as an exhibit to the Registration Statement of which this
Prospectus forms a part and the Trust Indenture Act. The Guarantee will be held
by the Guarantee Trustee for the benefit of the holders of the Preferred
Securities.
 
GENERAL
 
   
     Pursuant to the Guarantee, Illinois Power will irrevocably and
unconditionally agree, to the extent set forth therein, to pay in full to the
holders of the Preferred Securities the Guarantee Payments (as defined herein)
(without duplication of amounts theretofore paid by Illinois Power Financing I),
to the extent not paid by Illinois Power Financing I, regardless of any defense,
right of set-off or counterclaim that Illinois Power Financing I may have or
assert. The following payments or distributions with respect to the Preferred
Securities to the extent not paid or made by Illinois Power Financing I (the
"Guarantee Payments") will be subject to the Guarantee (without duplication):
(i) any accrued and unpaid distributions that are required to be paid on the
Preferred Securities, to the extent Illinois Power Financing I has funds
available therefor, (ii) the Redemption Price, including all accrued and unpaid
distributions to the date of the redemption, to the extent Illinois Power
Financing I has funds available therefore, with respect to any Preferred
Securities called for redemption by Illinois Power Financing I and (iii) upon a
voluntary or involuntary dissolution, winding-up or termination of Illinois
Power Financing I (other than in connection with the distribution of
Subordinated Debentures to the holders of Preferred Securities in exchange for
Preferred Securities), the lesser of (a) the aggregate of the liquidation amount
and all accrued and unpaid distributions on the Preferred Securities to the date
of payment, to the extent Illinois Power Financing I has funds available
therefor, and (b) the amount of assets of Illinois Power Financing I remaining
available for distribution to holders of Preferred Securities in termination of
Illinois Power Financing I. Illinois Power's obligation to make a Guarantee
Payment may be satisfied by direct payment of the required amounts by Illinois
Power to the holders of Preferred Securities or by causing Illinois Power
Financing I to pay such amounts to such holders.
    
 
   
     The Guarantee will be a guarantee of the Guarantee Payments with respect to
the Preferred Securities from the time of issuance of the Preferred Securities,
but will not apply to the payment of distributions and other payments on the
Preferred Securities when the Property Trustee does not have sufficient funds in
the Property Account to make such distributions or other payments. If Illinois
Power does not make interest payments on the Subordinated Debentures held by the
Property Trustee, Illinois Power Financing I will not make distributions on the
Preferred Securities issued by Illinois Power Financing I and will not have
funds available therefor. See "Description of the Subordinated Debentures --
Certain Covenants."
    
 
     Illinois Power will also agree separately to irrevocably and
unconditionally guarantee the obligations of Illinois Power Financing I with
respect to the Common Securities (the "Common Securities Guarantee") to the same
extent as the Guarantee, except that upon the occurrence and during the
continuation of an Indenture Event of Default, holders of Preferred Securities
shall have priority over holders of Common Securities with respect to
distributions and payments on liquidation, redemption or otherwise.
 
                                       21
<PAGE>   23
 
CERTAIN COVENANTS OF ILLINOIS POWER
 
     In the Guarantee, Illinois Power will covenant that, so long as the
Preferred Securities remain outstanding, if there shall have occurred and is
continuing any event that would constitute an event of default under the
Guarantee or the Declaration, then (a) Illinois Power shall not declare or pay
any dividend on, or make any distribution with respect to, or redeem, purchase,
acquire or make a liquidation payment with respect to, any of its capital stock,
provided, however, Illinois Power may declare and pay a stock dividend where the
dividend stock is the same stock as that on which the dividend is being paid,
(b) Illinois Power shall not make any payment of interest, principal or premium,
if any, on or repay, repurchase or redeem any debt securities (including
guarantees) issued by Illinois Power which rank pari passu with or junior to the
Subordinated Debentures, and (c) Illinois Power shall not make any guarantee
payments with respect to the foregoing (other than pursuant to the Guarantee).
 
AMENDMENTS AND ASSIGNMENT
 
     Except with respect to any changes which do not materially adversely affect
the rights of holders of Preferred Securities (in which case no vote will be
required), the Guarantee may be amended only with the prior approval of the
holders of not less than 66 2/3% in liquidation amount of the outstanding
Preferred Securities. The manner of obtaining any such approval of holders of
the Preferred Securities is set forth under "Description of the Preferred
Securities -- Voting Rights." All guarantees and agreements contained in the
Guarantee shall bind the successors, assigns, receivers, trustees and
representatives of Illinois Power and shall inure to the benefit of the
Guarantee Trustee and the holders of the Preferred Securities then outstanding.
 
TERMINATION OF THE GUARANTEE
 
   
     The Guarantee will terminate and be of no further force and effect as to
the Preferred Securities upon full payment of the Redemption Price of all
Preferred Securities, or upon distribution of the Subordinated Debentures to the
holders of the Preferred Securities, and will terminate completely upon full
payment of the amounts payable upon termination of Illinois Power Financing I.
See "Description of the Subordinated Debentures -- Indenture Events of Default"
for a description of the events of default and enforcement rights of the holders
of Subordinated Debentures. The Guarantee will continue to be effective or will
be reinstated, as the case may be, if at any time any holder of Preferred
Securities must repay to Illinois Power Financing I or Illinois Power, or their
successors, any sums paid to them under such Preferred Securities or the
Guarantee.
    
 
EVENTS OF DEFAULT
 
     An event of default under the Guarantee will occur upon the failure of
Illinois Power to perform any of its payment or other obligations thereunder.
 
   
     The holders of a majority in liquidation amount 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 the Guarantee or
to direct the exercise of any trust or power conferred upon the Guarantee
Trustee under the Guarantee. If the Guarantee Trustee fails to enforce the
Guarantee, any holder of Preferred Securities may institute a legal proceeding
directly against Illinois Power to enforce the Guarantee Trustee's rights under
the Guarantee without first instituting a legal proceeding against Illinois
Power Financing I, the Guarantee Trustee or any other person or entity.
    
 
STATUS OF THE GUARANTEE
 
     Illinois Power's obligations under the Guarantee to make the Guarantee
Payments will constitute an unsecured obligation of Illinois Power and will rank
(i) subordinate and junior in right of payment to all other liabilities of
Illinois Power, including the Subordinated Debentures, except those liabilities
of Illinois Power made pari passu or subordinate by their terms, (ii) pari passu
with the most senior preferred stock now or hereafter issued by Illinois Power
and with any guarantee now or hereafter entered into by Illinois Power in
respect of any preferred stock of any affiliate of Illinois Power, and (iii)
senior to Illinois Power's common
 
                                       22
<PAGE>   24
 
stock. The terms of the Preferred Securities provide that each holder of
Preferred Securities by acceptance thereof agrees to the subordination
provisions and other terms of the Guarantee.
 
     The Guarantee will constitute a guarantee of payment and not of collection
(that is, the guaranteed party may institute a legal proceeding directly against
the guarantor to enforce its rights under the guarantee without instituting a
legal proceeding against any other person or entity). The Guarantee will be
deposited with the Guarantee Trustee to be held for the benefit of the holders
of the Preferred Securities. Except as otherwise noted herein, the Guarantee
Trustee has the right to enforce the Guarantee on behalf of the holders of the
Preferred Securities. The Guarantee will not be discharged except by payment of
the Guarantee Payments in full (without duplication of amounts theretofore paid
by Illinois Power Financing I).
 
INFORMATION CONCERNING THE GUARANTEE TRUSTEE
 
     The Guarantee Trustee, prior to the occurrence of a default with respect to
the Guarantee and after the curing of all such defaults that may have occurred,
undertakes to perform only such duties as are specifically set forth in the
Guarantee and, after default, shall 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 the Guarantee at the request of any
holder of Preferred Securities, unless offered reasonable indemnity against the
costs, expenses and liabilities which might be incurred thereby; but the
foregoing shall not relieve the Guarantee Trustee, upon the occurrence of an
event of default under the Guarantee from exercising the rights and powers
vested in it by the Guarantee. The Guarantee Trustee also serves as Property
Trustee and Indenture Trustee.
 
GOVERNING LAW
 
     The Guarantee will be governed by, and construed in accordance with, the
internal laws of the State of Illinois.
 
                   DESCRIPTION OF THE SUBORDINATED DEBENTURES
 
     Set forth below is a description of the terms of the Subordinated
Debentures in which Illinois Power Financing I will invest the proceeds from the
issuance and sale of the Trust Securities. The following description does not
purport to be complete and is subject to, and is qualified in its entirety by
reference to, the Indenture, dated as of             , 1995, (the "Base
Indenture") between Illinois Power and Wilmington Trust Company, as Trustee (the
"Indenture Trustee"), as supplemented by a First Supplemental Indenture, dated
as of             , 1995 (the Base Indenture, as so supplemented, is hereinafter
referred to as the "Indenture"), the forms of which are filed as Exhibits to the
Registration Statement of which this Prospectus forms a part. The terms of the
Subordinated Debentures will include those stated in the Indenture and those
made a part of the Indenture by reference to the Trust Indenture Act. Certain
capitalized terms used herein are defined in the Indenture.
 
     Under certain circumstances involving the termination of Illinois Power
Financing I following the occurrence of a Special Event, Subordinated Debentures
may be distributed to the holders of the Trust Securities. See "Description of
the Preferred Securities -- Special Event Redemption or Distribution."
 
     If the Subordinated Debentures are distributed to the holders of the
Preferred Securities, Illinois Power will use its best efforts to have the
Subordinated Debentures listed on the New York Stock Exchange or on such other
national securities exchange or similar organization on which the Preferred
Securities are then listed or quoted.
 
GENERAL
 
   
     The Subordinated Debentures will be issued as unsecured subordinated debt
under the Indenture. The Subordinated Debentures will be limited in aggregate
principal amount to $103,100,000, such amount being the sum of the aggregate
stated liquidation amount of the Preferred Securities and the contributions made
by Illinois Power in exchange for the Common Securities (the "Illinois Power
Payment").
    
 
                                       23
<PAGE>   25
 
     The Amended and Restated Articles of Incorporation of Illinois Power limit
the amount of unsecured indebtedness that Illinois Power may issue or assume,
without the consent of the holders of a majority of the total number of shares
of preferred stock then outstanding, to 20% of the aggregate of the total
principal amount of all outstanding bonds or other securities representing
secured indebtedness of Illinois Power and the capital and surplus of Illinois
Power as then stated on Illinois Power's books. At September 30, 1995, Illinois
Power could have issued approximately $308 million of unsecured indebtedness
(such as the Subordinated Debentures) without violating this provision.
 
     The Subordinated Debentures are not subject to a sinking fund provision.
The entire principal amount of the Subordinated Debentures will mature and
become due and payable, together with any accrued and unpaid interest thereon
including Compound Interest (as defined herein) and Additional Interest (as
defined herein), if any, on             , 2044.
 
     If Subordinated Debentures are distributed to holders of Preferred
Securities in liquidation of such holders' interests in Illinois Power Financing
I, such Subordinated Debentures will initially be issued as a Global Security
(as defined herein). As described herein, under certain limited circumstances,
Subordinated Debentures may be issued in certificated form in exchange for a
Global Security. See "-- Book-Entry and Settlement" below. In the event that
Subordinated Debentures are issued in certificated form, such Subordinated
Debentures will be in denominations of $25 and integral multiples thereof and
may be transferred or exchanged at the offices described below. Payments on
Subordinated Debentures issued as a Global Security will be made to DTC, a
successor depositary or, in the event that no depositary is used, to a Paying
Agent for the Subordinated Debentures. In the event Subordinated Debentures are
issued in certificated form, principal and interest will be payable, the
transfer of the Subordinated Debentures will be registrable and Subordinated
Debentures will be exchangeable for Subordinated Debentures of other
denominations of a like aggregate principal amount at the corporate trust office
of the Indenture Trustee in Wilmington, Delaware; provided, that payment of
interest may be made at the option of Illinois Power by check mailed to the
address of the persons entitled thereto.
 
     The Indenture does not contain provisions that afford holders of the
Subordinated Debentures protection in the event of a highly leveraged
transaction involving Illinois Power.
 
SUBORDINATION
 
     The Indenture provides that the Subordinated Debentures are subordinated
and junior in right of payment to all Senior Indebtedness of Illinois Power,
whether now existing or hereafter incurred. No payment of principal (including
redemption payments, if any), premium, if any, or interest on, the Subordinated
Debentures may be made if (i) any Senior Indebtedness of Illinois Power is not
paid when due, and any applicable grace period with respect to such default has
ended and such default has not been cured or waived or ceased to exist, or (ii)
the maturity of any Senior Indebtedness of Illinois Power has been accelerated
because of a default. Upon any distribution of assets of Illinois Power to
creditors upon any dissolution, winding-up, liquidation or reorganization,
whether voluntary or involuntary, or in bankruptcy, insolvency, receivership or
other proceedings, all principal, premium, if any, and interest due or to become
due on all Senior Indebtedness of Illinois Power must be paid in full before the
holders of Subordinated Debentures are entitled to receive or retain any
payment. Upon satisfaction of all claims of all Senior Indebtedness then
outstanding, the rights of the holders of the Subordinated Debentures will be
subrogated to the rights of the holders of Senior Indebtedness of Illinois Power
to receive payments or distributions applicable to Senior Indebtedness until all
amounts owing on the Subordinated Debentures are paid in full.
 
     The term "Senior Indebtedness" means, with respect to Illinois Power, (i)
the principal, premium, if any, interest on and any other payment in respect of
(A) indebtedness of Illinois Power for money borrowed and (B) indebtedness
evidenced by securities, debentures, bonds or other similar instruments issued
by Illinois Power, including, without limitation, indebtedness evidenced by
securities issued pursuant to its Mortgage and Deed of Trust dated November 1,
1943, as supplemented, and its General Mortgage Indenture and Deed of Trust
dated as of November 1, 1992, (ii) all capital lease obligations of Illinois
Power, (iii) all obligations of Illinois Power issued or assumed as the deferred
purchase price of property, all conditional sale obligations of
 
                                       24
<PAGE>   26
 
Illinois Power and all obligations of Illinois Power under any title retention
agreement (but excluding trade accounts payable arising in the ordinary course
of business), (iv) all obligations of Illinois Power for the reimbursement on
any letter of credit, banker's acceptance, security purchase facility or similar
credit transaction, (v) all obligations of the type referred to in clauses (i)
through (iv) above of other persons for the payment of which Illinois Power is
responsible or liable as obligor, guarantor or otherwise and (vi) all
obligations of the type referred to in clauses (i) through (v) above of other
persons secured by any lien on any property or asset of Illinois Power (whether
or not such obligation is assumed by Illinois Power), except for (1) any such
indebtedness that is by its terms subordinated to or pari passu with the
Subordinated Debentures and (2) any indebtedness between or among Illinois Power
or its affiliates, including all other debt securities and guarantees in respect
of those debt securities, issued to any other trust, or a trustee of such trust,
partnership or other entity affiliated with Illinois Power that is a financing
vehicle of Illinois Power (a "financing entity") in connection with the issuance
by such financing entity of Preferred Securities or other securities that rank
pari passu with, or junior to, the Preferred Securities. Such Senior
Indebtedness shall continue to be Senior Indebtedness and be entitled to the
benefits of the subordination provisions irrespective of any amendment,
modification or waiver of any term of such Senior Indebtedness. In October 1994,
Illinois Power issued $100 million of Series A Subordinated Debentures to
Illinois Power Capital, L.P., a financing entity which issued cumulative monthly
income preferred securities that rank pari passu with the Preferred Securities.
 
     The Indenture does not limit the aggregate amount of Senior Indebtedness
that may be issued by Illinois Power. As of September 30, 1995, Senior
Indebtedness of Illinois Power aggregated approximately $2.2 billion.
 
CERTAIN COVENANTS
 
     If (i) there shall have occurred any event that would constitute an
Indenture Event of Default or (ii) Illinois Power shall be in default with
respect to its payment of any obligations under the Guarantee or the Common
Securities Guarantee, then (a) Illinois Power shall not declare or pay any
dividend on, make any distributions with respect to, or redeem, purchase or make
a liquidation payment with respect to, any of its capital stock, provided,
however, Illinois Power may declare and pay a stock dividend where the dividend
stock is the same stock as that on which the dividend is being paid, (b)
Illinois Power shall not make any payment of interest, principal or premium, if
any on or repay, repurchase or redeem any debt securities issued by Illinois
Power which rank pari passu with or junior to the Subordinated Debentures, and
(c) Illinois Power shall not make any guarantee payments with respect to the
foregoing (other than pursuant to the Guarantee).
 
     If Illinois Power shall have given notice of its election of an Extension
Period as provided in the Indenture and such period, or any extension thereof,
shall be continuing, then (a) Illinois Power shall not declare or pay any
dividend on, make any distributions with respect to, or redeem, purchase or make
a liquidation payment with respect to, any of its capital stock, provided,
however, Illinois Power may declare and pay a stock dividend where the dividend
stock is the same stock as that on which the dividend is being paid, (b)
Illinois Power shall not make any payment of interest, principal or premium, if
any, on or repay, repurchase or redeem any debt securities (including
guarantees) issued by Illinois Power which rank pari passu with or junior to the
Subordinated Debentures, and (c) Illinois Power shall not make any guarantee
payments with respect to the foregoing (other than pursuant to the Guarantee).
 
     For so long as the Trust Securities remain outstanding, Illinois Power will
covenant (i) to directly or indirectly maintain 100% direct or indirect
ownership of the Common Securities of the Trust; provided, however, that any
permitted successor of Illinois Power under the Indenture may succeed to
Illinois Power's ownership of such Common Securities, (ii) not to cause, as
sponsor of Illinois Power Financing I, or to permit, as holder of the Common
Securities, the dissolution, winding-up or termination of Illinois Power
Financing I, except in connection with a distribution of the Subordinated
Debentures as provided in the Declaration and in connection with certain
mergers, consolidations or amalgamation and (iii) to use its reasonable efforts
to cause Illinois Power Financing I (a) to remain a statutory business trust,
except in connection with the distribution of Subordinated Debentures to the
holders of Trust Securities in termination of Illinois Power Financing I, the
redemption of all of the Trust Securities of Illinois Power Financing I, or
certain mergers,
 
                                       25
<PAGE>   27
 
consolidations or amalgamations, each as permitted by the Declaration, and (b)
to otherwise continue to be classified as a grantor trust for United States
federal income purposes with each holder of Preferred Securities being treated
as owning an undivided beneficial interest in the Subordinated Debentures.
 
OPTIONAL REDEMPTION
 
     Illinois Power shall have the right to redeem the Subordinated Debentures,
in whole or in part, from time to time, on or after                , 2000, or at
any time in certain circumstances 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 nor 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. If a partial redemption of the Preferred Securities resulting
from a partial redemption of the Subordinated Debentures would result in the
delisting of the Preferred Securities by such exchange on which the Preferred
Securities are then listed, Illinois Power may only redeem the Subordinated
Debentures in whole.
 
INTEREST
 
     Each Subordinated Debenture shall bear interest at the rate of   % per
annum from the original date of issuance, payable quarterly in arrears on March
31, June 30, September 30, and December 31 of each year (each an "Interest
Payment Date"), commencing December 31, 1995, to the person in whose name such
Subordinated Debenture is registered, subject to certain exceptions, at the
close of business on the Business Day next preceding such Interest Payment Date.
In the event the Subordinated Debentures shall not continue to remain in
book-entry only form, Illinois Power shall have the right to select record
dates, which shall be more than one Business Day prior to the Interest Payment
Date.
 
     The amount of interest payable for any period will be computed on the basis
of a 360-day year of twelve 30-day months. The amount of interest payable for
any period shorter than a full quarterly period for which interest is computed,
will be computed on the basis of the actual number of days elapsed per 30-day
month. In the event that any date on which interest is payable on the
Subordinated Debentures is not a Business Day, then payment of the interest
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 is in the next succeeding calendar year, then
such payment shall be made on the immediately preceding Business Day, in each
case with the same force and effect as if made on such date.
 
OPTION TO EXTEND INTEREST PAYMENT PERIOD
 
     Illinois Power shall have the right at any time, and from time to time,
during the term of the Subordinated Debentures to defer payments of interest by
extending the interest payment period for a period not exceeding 20 consecutive
quarters, at the end of which Extension Period, Illinois Power shall pay all
interest then accrued and unpaid (including any Additional Interest) together
with interest thereon compounded quarterly at the rate specified for the
Subordinated Debentures to the extent permitted by applicable law ("Compound
Interest"); provided, that during any such Extension Period, (a) Illinois Power
shall not declare or pay dividends on, make any distribution with respect to, or
redeem, purchase, acquire or make a liquidation payment with respect to any of
its capital stock, provided, however, Illinois Power may declare and pay a stock
dividend where the dividend stock is the same stock as that on which the
dividend is being paid, (b) Illinois Power shall not make any payment of
interest, principal or premium, if any, on or repay, repurchase or redeem any
debt securities issued by Illinois Power that rank pari passu with or junior to
the Subordinated Debentures, and (c) Illinois Power shall not make any guarantee
payments with respect to the foregoing (other than pursuant to the Guarantee).
Prior to the termination of any such Extension Period, Illinois Power may
further defer payments of interest by extending the interest payment period;
provided, however, that, such Extension Period, including all such previous and
further extensions, may not exceed 20 consecutive quarters or extend beyond the
maturity of the Subordinated Debentures. Upon the termination of any Extension
Period and the payment of all amounts then due, Illinois Power may commence a
new Extension Period, subject to the terms set forth in this section. No
interest during an Extension Period, except
 
                                       26
<PAGE>   28
 
at the end thereof, shall be due and payable. Illinois Power has no present
intention of exercising its right to defer payments of interest by extending the
interest payment period on the Subordinated Debentures. If the Property Trustee
shall be the sole holder of the Subordinated Debentures, Illinois Power shall
give the Regular Trustees and the Property Trustee notice of its election of
such Extension Period one Business Day prior to the earlier of (i) the date
distributions on the Preferred Securities are payable or (ii) the date the
Regular Trustees are required to give notice to the New York Stock Exchange (or
other applicable self-regulatory organization) or to holders of the Preferred
Securities of the record date or the date such distribution is payable. The
Regular Trustees shall give notice of Illinois Power's selection of such
Extension Period to the holders of the Preferred Securities. If the Property
Trustee shall not be the sole holder of the Subordinated Debentures, Illinois
Power shall give the holders of the Subordinated Debentures notice of its
election of such Extension Period ten Business Days prior to the earlier of (i)
the Interest Payment Date or (ii) the date upon which Illinois Power is required
to give notice to the New York Stock Exchange (or other applicable self-
regulatory organization) or to holders of the Subordinated Debentures of the
record or payment date of such related interest payment.
 
ADDITIONAL INTEREST
 
     If at any time Illinois Power Financing I or the Property Trustee shall be
required to pay any taxes, duties, assessments or governmental charges of
whatever nature (other than withholding taxes) imposed by the United States, or
any other taxing authority, then, in any such case, Illinois Power will pay as
additional interest ("Additional Interest") such additional amounts as shall be
required so that the net amounts received and retained by Illinois Power
Financing I after paying any such taxes, duties, assessments or other
governmental charges will be not less than the amounts Illinois Power Financing
I and the Property Trustee would have received had no such taxes, duties,
assessments or other governmental charges been imposed.
 
INDENTURE EVENTS OF DEFAULT
 
     In case any Indenture Event of Default shall occur and be continuing, the
Property Trustee, as the holder of the Subordinated Debentures, will have the
right to declare the principal of and the interest on the Subordinated
Debentures (including any Compound Interest and Additional Interest, if any) and
any other amounts payable under the Indenture to be forthwith due and payable
and to enforce its other rights as a creditor with respect to the Subordinated
Debentures.
 
     The Indenture provides that any one or more of the following described
events, which has occurred and is continuing, constitutes an "Event of Default"
with respect to the Subordinated Debentures:
 
          (a) failure for 30 days to pay interest on the Subordinated
     Debentures, including any Additional Interest in respect thereof, when due;
     provided, however, that a valid extension of the interest payment period by
     Illinois Power shall not constitute a default in the payment of interest
     for this purpose; or
 
          (b) failure to pay principal or premium, if any, on the Subordinated
     Debentures when due whether at maturity, upon earlier redemption or
     otherwise; or
 
          (c) failure to observe or perform any other covenant or agreement
     (other than those specifically relating to another series of subordinated
     debt securities) contained in the Indenture or established pursuant thereto
     for 90 days after written notice to Illinois Power from the Indenture
     Trustee or the holders of at least 25% in principal amount of the
     outstanding Subordinated Debentures; or
 
          (d) certain events of bankruptcy, insolvency or reorganization of
     Illinois Power; or
 
   
          (e) the voluntary or involuntary dissolution, winding-up or
     termination of Illinois Power Financing I, except in connection with the
     distribution of Subordinated Debentures to the holders of Preferred
     Securities upon termination of Illinois Power Financing I, the redemption
     of all outstanding Trust Securities of Illinois Power Financing I and
     certain mergers, consolidations or amalgamations permitted by the
     Declaration.
    
 
                                       27
<PAGE>   29
 
     The holders of a majority in aggregate outstanding principal amount of the
Subordinated Debentures have the right to direct the time, method, and place of
conducting any proceeding for any remedy available to the Indenture Trustee. The
Indenture Trustee or the holders of not less than 25% in aggregate outstanding
principal amount of the Subordinated Debentures may declare the principal due
and payable immediately on default, but the holders of a majority in aggregate
outstanding principal amount may annul such declaration and waive the default if
the default has been cured and a sum sufficient to pay all matured installments
of interest and principal due otherwise than by acceleration and any applicable
premium has been deposited with the Indenture Trustee.
 
     The holders of a majority in aggregate outstanding principal amount of the
Subordinated Debentures affected thereby may, on behalf of the holders of all
the Subordinated Debentures, waive any past default, except (i) a default in the
payment of principal, premium, if any, 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 and any applicable premium has been
deposited with the Indenture Trustee) or (ii) a default in the covenant of
Illinois Power not to declare or pay dividends on, or make distributions with
respect to, or redeem, purchase or acquire any of its capital stock during an
Extension Period. An Indenture Event of Default also constitutes a Declaration
Event of Default. The holders of Preferred Securities in certain circumstances
have the right to direct the Property Trustee to exercise its rights as the
holder of the Subordinated Debentures. See "Description of the Preferred
Securities -- Declaration Events of Default" and "-- Voting Rights."
 
BOOK-ENTRY AND SETTLEMENT
 
   
     If distributed to holders of Preferred Securities in connection with the
involuntary or voluntary dissolution, winding-up or termination of Illinois
Power Financing I as a result of the occurrence of a Special Event, the
Subordinated Debentures will be issued in the form of one or more global
certificates (each a "Global Security") registered in the name of the Depositary
or its nominee. Except under the limited circumstances described below,
Subordinated Debentures represented by the Global Security will not be
exchangeable for, and will not otherwise be issuable as, Subordinated Debentures
in definitive form. The Global Securities described above may not be transferred
except 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 or to a
successor depositary or its nominee.
    
 
     The laws of some jurisdictions require that certain purchasers of
securities take physical delivery of such securities in definitive form. Such
laws may impair the ability to transfer beneficial interests in such a Global
Security.
 
     Except as provided below, owners of beneficial interests in such a Global
Security will not be entitled to receive physical delivery of Subordinated
Debentures in definitive form and will not be considered the holders (as defined
in the Indenture) thereof for any purpose under the Indenture, and no Global
Security representing Subordinated Debentures shall be exchangeable, except for
another Global Security of like denomination and tenor to be registered in the
name of the Depositary or its nominee or to a successor Depositary or its
nominee. Accordingly, each Beneficial Owner must rely on the procedures of the
Depositary or if such person is not a Participant, on the procedures of the
Participant through which such person owns its interest to exercise any rights
of a holder under the Indenture.
 
THE DEPOSITARY
 
     If Subordinated Debentures are distributed to holders of Preferred
Securities in liquidation of such holders' interests in Illinois Power Financing
I, DTC will act as securities depositary (the "Depositary") for the Subordinated
Debentures. For a description of DTC and the specific terms of the depositary
arrangements, see "Description of the Preferred Securities -- Book-Entry Only
Issuance -- The Depository Trust Company." As of the date of this Prospectus,
the description therein of DTC's book-entry system and DTC's practices as they
relate to purchases, transfers, notices and payments with respect to the
Preferred Securities apply in all material respects to any debt obligations
represented by one or more Global Securities held by
 
                                       28
<PAGE>   30
 
DTC. Illinois Power may appoint a successor to DTC or any successor depositary
in the event DTC or such successor depositary is unable or unwilling to continue
as a depositary for the Global Securities.
 
     None of Illinois Power, Illinois Power Financing I, the Indenture Trustee,
any paying agent and any other agent of Illinois Power or the Indenture Trustee
will have any responsibility or liability for any aspect of the records relating
to or payments made on account of beneficial ownership interests in a Global
Security for such Subordinated Debentures or for maintaining, supervising or
reviewing any records relating to such beneficial ownership interests.
 
DISCONTINUANCE OF THE DEPOSITARY'S SERVICES
 
     A Global Security shall be exchangeable for Subordinated Debentures
registered in the names of persons other than the Depositary or its nominee only
if (i) the Depositary notifies Illinois Power that it is unwilling or unable to
continue as a depositary for such Global Security and no successor depositary
shall have been appointed, (ii) the Depositary, at any time, ceases to be a
clearing agency registered under the Exchange Act at which time the Depositary
is required to be so registered to act as such depositary and no successor
depositary shall have been appointed or (iii) Illinois Power, in its sole
discretion, determines that such Global Security shall be so exchangeable. Any
Global Security that is exchangeable pursuant to the preceding sentence shall be
exchangeable for Subordinated Debentures registered in such names as the
Depositary shall direct. It is expected that such instructions will be based
upon directions received by the Depositary from its Participants with respect to
ownership of beneficial interests in such Global Security.
 
     In the event the Subordinated Debentures are not represented by one or more
Global Securities, certificates evidencing Subordinated Debentures may be
presented for registration of transfer (with the form of transfer endorsed
thereon duly executed) or exchange, at the office of the Security Registrar or
at the office of any transfer agent designated by Illinois Power for such
purpose with respect to the Subordinate Debentures without service charge and
upon payment of any taxes and other governmental charges as described in the
Indenture. Such transfer or exchange will be effected upon the Security
Registrar or such transfer agent, as the case may be, being satisfied with the
documents of title and identity of the person making the request. Illinois Power
has appointed the Indenture Trustee as Security Registrar with respect to the
Subordinated Debentures. Illinois Power may at any time rescind the designation
of any such transfer agent or approve a change in the location through which any
such transfer agent acts, except that Illinois Power will be required to
maintain a transfer agent at the place of payment. Illinois Power may at any
time designate additional transfer agents with respect to the Subordinated
Debentures.
 
     In the event of any redemption in part, Illinois Power shall not be
required to (i) issue, exchange or register the transfer of Subordinated
Debentures during a period beginning at the opening of business 15 days before
the date of the mailing of a notice of redemption of less than all of the
Subordinated Debentures and ending at the close of business on the date of such
mailing and (ii) register the transfer of or exchange any Subordinated
Debentures so selected for redemption, in whole or in part, except the
unredeemed portion of any Subordinated Debentures being redeemed in part.
 
MODIFICATION OF THE INDENTURE
 
     The Indenture contains provisions permitting Illinois Power and the
Indenture Trustee, with the consent of the holders of at least 66 2/3% in
principal amount of the Subordinated Debentures, to modify the Indenture or any
supplemental indenture affecting that series or the rights of the holders of the
Subordinated Debentures; provided that no such modification may, without the
consent of the holder of each outstanding Subordinated Debentures affected
thereby, (i) extend the fixed maturity of the Subordinated Debentures, or reduce
the principal amount thereof, or reduce the rate or extend the time of payment
of interest thereon, or reduce any premium payable upon the redemption thereof,
without the consent of the holder of the Subordinated Debentures so affected or
(ii) reduce the percentage of Subordinated Debentures, the holders of which are
required to consent to any such supplemental indenture, without the consent of
the holders of each Subordinated Debenture then outstanding and affected
thereby.
 
                                       29
<PAGE>   31
 
     In addition, Illinois Power and the Indenture Trustee may execute, without
the consent of holders of the Subordinated Debentures, any supplemental
indenture for certain other usual purposes including the creation of any new
series of subordinated debt securities.
 
CONSOLIDATION, MERGER AND SALE
 
     The Indenture does not contain any covenant which restricts Illinois
Power's ability to merge or consolidate with or into any other corporation, sell
or convey all or substantially all of its assets to any person, firm or
corporation or otherwise engage in restructuring transactions.
 
DEFEASANCE AND DISCHARGE
 
     Under the terms of the Indenture, Illinois Power will be discharged from
any and all obligations in respect of the Subordinated Debentures (except in
each case for certain obligations with respect to denominations and provisions
for payment of the Subordinated Debentures and obligations to register the
transfer or exchange of Subordinated Debentures, replace stolen, lost or
mutilated Subordinated Debentures, maintain paying agencies and hold moneys for
payment in trust) if Illinois Power (i) deposits with the Indenture Trustee, in
trust, moneys or governmental obligations, in an amount sufficient to pay all
the principal of, and interest on, the Subordinated Debentures on the dates such
payments are due in accordance with the terms of such Subordinated Debentures
and (ii) delivered to the Indenture Trustee an opinion of counsel to the effect
that, based upon Illinois Power's receipt from, or the publication by, the
Internal Revenue Service of a ruling or a change in law, the holders of the
Subordinated Debentures will not recognize income, gain or loss for United
States federal income tax purposes as a result of the deposit, defeasance and
discharge and will be subject to United States federal income tax on the same
amount and in the same manner and at the same times as would have been the case
if such deposit, defeasance or discharge had not occurred.
 
GOVERNING LAW
 
     The Indenture and the Subordinated Debentures will be governed by, and
construed in accordance with, the internal laws of the State of New York.
 
INFORMATION CONCERNING THE INDENTURE TRUSTEE
 
     The Indenture Trustee, prior to default, undertakes to perform only such
duties as are specifically set forth in the Indenture and, after default, shall
exercise 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
Indenture at the request of any holder of Subordinated Debentures, unless
offered reasonable indemnity by such holder against the costs, expenses and
liabilities which might be incurred thereby; but the foregoing shall not relieve
the Indenture Trustee, upon the occurrence of an Indenture Event of Default,
from exercising the rights and powers vested in it by the Indenture. The
Indenture Trustee is not required to expand or risk its own funds or otherwise
incur personal 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.
 
MISCELLANEOUS
 
     Illinois Power will have the right at all times to assign any of its rights
or obligations under the Indenture to a direct or indirect wholly-owned
subsidiary of Illinois Power; provided that, in the event of any such
assignment, Illinois Power will remain liable for all of their obligations.
Subject to the foregoing, the Indenture will be binding upon and inure to the
benefit of the parties thereto and their respective successors and assigns. The
Indenture provides that it may not otherwise be assigned by the parties thereto.
 
     The Indenture will provide that Illinois Power will pay all fees and
expenses related to (i) the offering of the Trust Securities and the
Subordinated Debentures, (ii) the organization, maintenance and dissolution of
Illinois Power Financing I, (iii) the taxes of Illinois Power Financing I (other
than United States withholding
 
                                       30
<PAGE>   32
 
taxes attributable to Illinois Power Financing I or its assets), (iv) the
retention of the Illinois Power Trustees and (v) the enforcement by the Property
Trustee of the rights of holders of Preferred Securities.
 
                        EFFECT OF OBLIGATIONS UNDER THE
                   SUBORDINATED DEBENTURES AND THE GUARANTEE
 
     As set forth in the Declaration, the sole purpose of Illinois Power
Financing I is to issue the Trust Securities evidencing undivided beneficial
interests in the assets of Illinois Power Financing I and to invest the proceeds
from such issuance and sale in the Subordinated Debentures.
 
     As long as payments of interest and other payments are made when due on the
Subordinated Debentures, such payments will be sufficient to cover distributions
and payments due on the Trust Securities because of the following factors: (i)
the aggregate principal amount of Subordinated Debentures will be equal to the
sum of the aggregate liquidation amount of the Trust Securities; (ii) the
interest rate and the interest and other payment dates on the Subordinated
Debentures will match the distribution rate and distribution and other payment
dates for the Preferred Securities; (iii) Illinois Power shall pay all, and
Illinois Power Financing I shall not be obligated to pay, directly or
indirectly, any costs and expenses of Illinois Power Financing I; and (iv) the
Declaration further provides that the Illinois Power Trustees shall not cause or
permit Illinois Power Financing I to, among other things, engage in any activity
that is not consistent with the purposes of Illinois Power Financing I.
 
   
     Payments of distributions (to the extent funds therefor are available) and
other payments due on the Preferred Securities (to the extent funds therefor are
available) are guaranteed by Illinois Power as and to the extent set forth under
"Description of the Preferred Securities Guarantee." If Illinois Power does not
make interest payments on the Subordinated Debentures purchased by Illinois
Power Financing I, Illinois Power Financing I will not have sufficient funds to
pay distributions on the Preferred Securities. The Guarantee is a guarantee from
the time of its issuance but does not apply to any payment of distributions
unless and until Illinois Power Financing I has sufficient funds for the payment
of such distributions.
    
 
     If Illinois Power fails to make interest or other payments on the
Subordinated Debentures when due (taking into account any Extension Period), the
Declaration provides a mechanism whereby the holders of the Preferred
Securities, using the procedures described in "Description of the Preferred
Securities -- Book-Entry Only Issuance -- The Depository Trust Company" and "--
Voting Rights," may direct the Property Trustee to enforce its rights under the
Subordinated Debentures. If the Property Trustee fails to enforce its rights
under the Subordinated Debentures to the fullest extent permitted by law, a
holder of Preferred Securities may institute a legal proceeding against Illinois
Power to enforce the Property Trustee's rights under the Subordinated Debentures
without first instituting any legal proceeding against the Property Trustee or
any other person or entity.
 
     If Illinois Power fails to make payments under the Guarantee, the Guarantee
provides a mechanism whereby the holders of the Preferred Securities may direct
the Guarantee Trustee to enforce its rights thereunder. If the Guarantee Trustee
fails to enforce the Guarantee, any holder of Preferred Securities may institute
a legal proceeding directly against Illinois Power to enforce the Guarantee
Trustee's rights under the Guarantee without first instituting a legal
proceeding against Illinois Power Financing I, the Guarantee Trustee, or any
other person or entity. Illinois Power, under the Guarantee, acknowledges that
the Guarantee Trustee shall enforce the Guarantee on behalf of the holders of
the Preferred Securities.
 
   
     The obligations of Illinois Power with respect to the Preferred Securities
under the Subordinated Debentures, the Indenture, the Guarantee and the
Declaration (including its obligation to pay the expenses of Illinois Power
Financing I), taken together, are equivalent to a full and unconditional
guarantee by Illinois Power of payments due on the Preferred Securities. See
"Description of the Preferred Securities Guarantee -- General."
    
 
                                       31
<PAGE>   33
 
                     UNITED STATES FEDERAL INCOME TAXATION
 
GENERAL
 
     The following is a summary of certain of the material United States federal
income tax consequences of the purchase, ownership and disposition of Preferred
Securities to a holder that is a citizen or resident of the United States, a
corporation, partnership or other entity created or organized under the laws of
the United States or any state thereof or the District of Columbia, or an estate
or trust the income of which is subject to United States federal income taxation
regardless of its source. Unless otherwise stated, this summary deals only with
Preferred Securities held as capital assets by holders who purchase the
Preferred Securities upon original issuance ("Initial Holders"). It does not
deal with special classes of holders such as banks, thrifts, real estate
investment trusts, regulated investment companies, insurance companies, dealers
in securities or currencies, tax-exempt investors, or persons that will hold the
Preferred Securities as a position in a "straddle," as part of a "synthetic
security" or "hedge," as part of a "conversion transaction" or other integrated
investment, or as other than a capital asset. This summary also does not address
the tax consequences to persons that have a functional currency other than the
U.S. Dollar or the tax consequences to shareholders, partners or beneficiaries
of a holder of Preferred Securities. Further, it does not include any
description of any alternative minimum tax consequences or the tax laws of any
state or local government or of any foreign government that may be applicable to
the Preferred Securities. This summary is based on the Internal Revenue Code of
1986, as amended (the "Code"), Treasury regulations thereunder (the "Treasury
Regulations") and administrative and judicial interpretations thereof, as of the
date hereof, all of which are subject to change, possibly on a retroactive
basis.
 
CLASSIFICATION OF THE SUBORDINATED DEBENTURES
 
     In connection with the issuance of the Subordinated Debentures, Schiff
Hardin & Waite, counsel to Illinois Power and Illinois Power Financing I, will
render its opinion generally to the effect that, although not entirely free from
doubt, under then current law and assuming full compliance with the terms of the
Indenture (and certain other documents), and based on certain facts and
assumptions contained in such opinion, the Subordinated Debentures held by
Illinois Power Financing I will be classified for United States federal income
tax purposes as indebtedness of Illinois Power.
 
CLASSIFICATION OF ILLINOIS POWER FINANCING I
 
     In connection with the issuance of the Preferred Securities, Schiff Hardin
& Waite, counsel to Illinois Power and Illinois Power Financing I, will render
its opinion generally to the effect that, under then current law and assuming
full compliance with the terms of the Declaration and the Indenture (and certain
other documents), and based on certain facts and assumptions contained in such
opinion, Illinois Power Financing 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, for United States federal income tax purposes, each
holder of Preferred Securities generally will be considered the owner of an
undivided interest in the Subordinated Debentures, and each holder will be
required to include in its gross income any OID accrued with respect to its
allocable share of those Subordinated Debentures.
 
ORIGINAL ISSUE DISCOUNT
 
     Because Illinois Power has the option, under the terms of the Subordinated
Debentures, to defer payments of interest by extending interest payment periods
for up to 20 quarters, all of the stated interest payments on the Subordinated
Debentures will be treated as OID. Holders of debt instruments issued with OID
must include that discount in income on an economic accrual basis before the
receipt of cash attributable to the interest, regardless of their method of tax
accounting. Generally, all of a holder's taxable interest income with respect to
the Subordinated Debentures will be accounted for as OID, and actual
distributions of stated interest will not be separately reported as taxable
income. The amount of OID that accrues in any month will approximately equal the
amount of the interest that accrues on the Subordinated Debentures in that month
at the stated interest rate. In the event that the interest payment period is
extended, holders will continue to
 
                                       32
<PAGE>   34
 
accrue OID approximately equal to the amount of the interest payment due at the
end of the Extension Period on an economic accrual basis over the length of the
Extension Period.
 
     In addition, the amount of OID will be increased or decreased if the issue
price of the Subordinated Debentures (offering price of the Preferred Securities
at the time of the issuance) is less than or greater than their stated principal
amount. It is anticipated that the issue price of the Subordinated Debentures
will equal or exceed their stated principal amount. In the event that the issue
price of the Subordinated Debentures is less than their stated principal amount,
however, the Treasury Regulations may be read to require a recalculation of the
amount of OID for each period that Illinois Power does not exercise its right to
extend the interest payment period. This recalculation could result in minor
adjustments to the amount of OID taxable to the Holders for such period.
 
     Because income on the Preferred Securities will constitute OID, corporate
holders of Preferred Securities will not be entitled to a dividends-received
deduction with respect to any income recognized with respect to the Preferred
Securities.
 
MARKET DISCOUNT AND BOND PREMIUM
 
     Holders of Preferred Securities other than Initial Holders may be
considered to have acquired their undivided interests in the Subordinated
Debentures with market discount or acquisition premium as such phrases are
defined for United States federal income tax purposes. Such holders are advised
to consult their tax advisors as to the income tax consequences of the
acquisition, ownership and disposition of the Preferred Securities.
 
RECEIPT OF SUBORDINATED DEBENTURES OR CASH UPON LIQUIDATION OF ILLINOIS POWER
FINANCING I
 
   
     Under certain circumstances, as described under the caption "Description of
the Preferred Securities -- Special Event Redemption or Distribution,"
Subordinated Debentures may be distributed to holders in exchange for the
Preferred Securities and upon termination of Illinois Power Financing I. Under
current law, such a distribution, for United States federal income tax purposes,
would be treated as a non-taxable event to each holder, and each holder would
receive an aggregate tax basis in the Subordinated Debentures equal to such
holder's aggregate tax basis in its Preferred Securities. A holder's holding
period in the Subordinated Debentures so received upon termination of Illinois
Power Financing I would include the period during which the Preferred Securities
were held by such holder.
    
 
     Under certain circumstances described herein (see "Description of the
Preferred Securities -- Special Event Redemption or Distribution"), the
Subordinated Debentures may be redeemed for cash and the proceeds of such
redemption distributed to holders in redemption of their Preferred Securities.
Under current law, such a redemption would, for United States federal income tax
purposes, constitute a taxable disposition of the redeemed Preferred Securities,
and a holder could recognize gain or loss as if it sold such redeemed Preferred
Securities for cash. See "United States Federal Income Taxation -- Sales of
Preferred Securities."
 
SALES OF PREFERRED SECURITIES
 
     A holder that sells Preferred Securities will recognize gain or loss equal
to the difference between its adjusted tax basis in the Preferred Securities and
the amount realized on the sale of such Preferred Securities. A holder's
adjusted tax basis in the Preferred Securities generally will be its initial
purchase price increased by OID previously includible in such holder's gross
income to the date of disposition and decreased by payments received on the
Preferred Securities. Such gain or loss generally will be a capital gain or loss
and generally will be a long-term capital gain or loss if the Preferred
Securities have been held for more than one year.
 
     The Preferred Securities may trade at a price that does not accurately
reflect the value of accrued but unpaid interest with respect to the underlying
Subordinated Debentures. A holder who disposes of his Preferred Securities
between record dates for payments of distributions thereon will be required to
include accrued but unpaid interest on the Subordinated Debentures through the
date of disposition in income as OID, and to add such amount to his adjusted tax
basis in his pro rata share of the underlying Subordinated
 
                                       33
<PAGE>   35
 
Debentures deemed disposed of. To the extent the selling price is less than the
holder's adjusted tax basis (which will include, in the form of OID, all accrued
but unpaid interest) a holder will recognize a capital loss. Subject to certain
limited exceptions, capital losses cannot be applied to offset ordinary income
for United States federal income tax purposes.
 
INFORMATION REPORTING TO HOLDERS
 
     Subject to the qualifications discussed below, income on the Preferred
Securities will be reported to holders on Forms 1099, which forms should be
mailed to holders of Preferred Securities by January 31 following each calendar
year.
 
     Illinois Power Financing I will be obligated to report annually to Cede &
Co., as holder of record of the Preferred Securities, the OID related to the
Subordinated Debentures that accrued during the year. Illinois Power Financing I
currently intends to report such information on Form 1099 prior to January 31
following each calendar year even though Illinois Power Financing I is not
legally required to report to record holders until April 15 following each
calendar year. The Underwriters (as defined herein) have indicated to Illinois
Power Financing I that, to the extent that they hold Preferred Securities as
nominees for beneficial holders, they currently expect to report to such
beneficial holders on Forms 1099 by January 31 following each calendar year.
Under current law, holders of Preferred Securities who hold as nominees for
beneficial holders will not have any obligation to report information regarding
the beneficial holders to Illinois Power Financing I. Illinois Power Financing
I, moreover, will not have any obligation to report to beneficial holders who
are not also record holders. Thus, beneficial holders of Preferred Securities
who hold their Preferred Securities through the Underwriters will receive Forms
1099 reflecting the income on their Preferred Securities from such nominee
holders rather than Illinois Power Financing I.
 
BACKUP WITHHOLDING
 
     Payments made on, and proceeds from the sale of, the Preferred Securities
may be subject to a "backup" withholding tax of 31% unless the holder complies
with certain identification requirements. Any withheld amounts will be allowed
as a credit against the holder's United States federal income tax, provided the
required information is provided to the Service.
 
     THE UNITED STATES FEDERAL INCOME TAX DISCUSSION SET FORTH ABOVE IS INCLUDED
FOR GENERAL INFORMATION ONLY AND MAY NOT BE APPLICABLE DEPENDING UPON A HOLDER'S
PARTICULAR SITUATION. HOLDERS SHOULD CONSULT THEIR TAX ADVISORS WITH RESPECT TO
THE TAX CONSEQUENCES TO THEM OF THE PURCHASE, OWNERSHIP AND DISPOSITION OF THE
PREFERRED SECURITIES, INCLUDING THE TAX CONSEQUENCES UNDER STATE, LOCAL, FOREIGN
AND OTHER TAX LAWS AND THE POSSIBLE EFFECTS OF CHANGES IN UNITED STATES FEDERAL
OR OTHER TAX LAWS.
 
                                       34
<PAGE>   36
 
                                  UNDERWRITING
 
     Subject to the terms and conditions set forth in an underwriting agreement
(the "Underwriting Agreement"), Illinois Power Financing I has agreed to sell to
each of the underwriters named below (the "Underwriters"), and each of the
Underwriters, for whom Merrill Lynch, Pierce, Fenner & Smith Incorporated, Smith
Barney Inc., Dean Witter Reynolds Inc., A.G. Edwards & Sons, Inc. and
PaineWebber Incorporated are acting as representatives (the "Representatives"),
has severally agreed to purchase the number of Preferred Securities set forth
opposite its name below. In the Underwriting Agreement, the several Underwriters
have agreed, subject to the terms and conditions set forth therein, to purchase
all of the Preferred Securities offered hereby if any of the Preferred
Securities are purchased. In the event of default by an Underwriter, the
Underwriting Agreement provides that, in certain circumstances, the purchase
commitments of the nondefaulting Underwriters may be increased or the
Underwriting Agreement may be terminated.
 
<TABLE>
<CAPTION>
                                                                                    NUMBER OF
                                       UNDERWRITER                             PREFERRED SECURITIES
                                       -----------                             --------------------
<S>                                                                            <C>
Merrill Lynch, Pierce, Fenner & Smith
             Incorporated...................................................
Smith Barney Inc. ..........................................................
Dean Witter Reynolds Inc. ..................................................
A.G. Edwards & Sons, Inc. ..................................................
PaineWebber Incorporated....................................................
                                                                               ---------------
             Total..........................................................         4,000,000
                                                                                ==============
</TABLE>
 
     The Underwriters propose to offer the Preferred Securities in part directly
to the public at the initial public offering price, as set forth on the cover
page of this Prospectus, and in part to certain securities dealers at such price
less a concession 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 Preferred Securities are
released for sale to the public, the offering price and other selling terms may
from time to time be varied by the Representatives.
 
     In view of the fact that the proceeds of the sale of the Preferred
Securities will be used to purchase the Subordinated Debentures of Illinois
Power, the Underwriting Agreement provides that Illinois Power will agree to pay
as compensation ("Underwriters' Compensation") to the Underwriters for the
Underwriters' arranging the investment therein of such proceeds, an amount in
New York Clearing House (next day) funds of $     per Preferred Security (or
$       in the aggregate) for the accounts of the several Underwriters, provided
that such compensation for sales of 10,000 or more Preferred Securities to any
single purchaser will be $     per Preferred Security. Therefore, to the extent
of such sales, the actual amount of Underwriters' Compensation will be less than
the aggregate amount specified in the preceding sentence.
 
     During a period of 30 days from the date of the pricing of the Preferred
Securities, neither Illinois Power Financing I nor Illinois Power will, without
the prior written consent of the Representatives, directly or indirectly, sell,
offer to sell, contract 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 the Subordinated
Debentures or any debt securities substantially similar to the Subordinated
Debentures or any equity securities substantially similar to the Preferred
Securities (except for the Subordinated Debentures and the Preferred Securities
offered hereby).
 
   
     Application has been made to list the Preferred Securities on the New York
Stock Exchange. If 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. The Representatives have advised Illinois Power Financing I
that the Underwriters intend to make a market in the Preferred Securities prior
to the commencement of trading on the New York Stock Exchange. The Underwriters
will have no obligation to make a market in the Preferred Securities, however,
any may cease market making activities, if commenced, at any time.
    
 
                                       35
<PAGE>   37
 
     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 New York Stock Exchange, the Underwriters will undertake to
sell lots of 100 or more Preferred Securities to a minimum of 400 beneficial
holders.
 
     Illinois Power and Illinois Power Financing I have agreed to indemnify the
Underwriters against, or to contribute to payments that the Underwriters may be
required to make in respect of, certain liabilities, including liabilities under
the Securities Act.
 
     Certain of the Underwriters engage in transactions with, and, from time to
time, have performed services for, Illinois Power in the ordinary course of
business.
 
                                 LEGAL MATTERS
 
     Certain legal matters will be passed upon for Illinois Power and Illinois
Power Financing I by Schiff Hardin & Waite, Chicago, Illinois, and for the
Underwriters by Reid & Priest LLP, New York, New York. 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 Illinois Power and Illinois Power Financing I. Schiff Hardin & Waite
may rely on the opinion of Reid & Priest LLP as to all matters of New York law,
and Reid & Priest LLP may rely on the opinion of Schiff Hardin & Waite as to all
matters of Illinois law.
 
                                    EXPERTS
 
     The financial statements incorporated in this Prospectus by reference to
Illinois Power's Annual Report on Form 10-K for the year ended December 31, 1994
have been so incorporated in reliance on the report of Price Waterhouse LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.
 
                                       36
<PAGE>   38
 
- ------------------------------------------------------
- ------------------------------------------------------
NO DEALER, SALESPERSON OR OTHER INDIVIDUAL HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATION OTHER THAN THOSE CONTAINED OR
INCORPORATED BY REFERENCE IN THIS PROSPECTUS IN CONNECTION WITH THE OFFER MADE
BY THIS PROSPECTUS AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS
MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY ILLINOIS POWER COMPANY,
ILLINOIS POWER FINANCING I OR THE UNDERWRITERS. NEITHER THE DELIVERY OF THIS
PROSPECTUS NOR ANY SALE MADE HEREUNDER SHALL UNDER ANY CIRCUMSTANCE CREATE AN
IMPLICATION THAT THERE HAS BEEN NO CHANGE IN THE AFFAIRS OF ILLINOIS POWER
COMPANY OR ILLINOIS POWER FINANCING I, SINCE THE DATE HEREOF. THIS PROSPECTUS
DOES NOT CONSTITUTE AN OFFER OR SOLICITATION BY ANYONE IN ANY STATE IN WHICH
SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN WHICH THE PERSON MAKING SUCH
OFFER OR SOLICITATION IS NOT QUALIFIED TO DO SO OR TO ANYONE TO WHOM IT IS
UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION.
 
                            ------------------------
                               TABLE OF CONTENTS
                                   PROSPECTUS
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
Available Information.................    3
Incorporation of Certain Documents by
  Reference...........................    3
Prospectus Summary....................    4
Risk Factors..........................    5
Illinois Power Company................    8
Illinois Power Financing I............    8
Summary Financial Information of
  Illinois Power......................   10
Accounting Treatment..................   11
Use of Proceeds.......................   11
Description of the Preferred
  Securities..........................   11
Description of the Preferred
  Securities Guarantee................   21
Description of the Subordinated
  Debentures..........................   23
Effect of Obligations Under the
  Subordinated Debentures and the
  Guarantee...........................   31
United States Federal Income
  Taxation............................   32
Underwriting..........................   35
Legal Matters.........................   36
Experts...............................   36
</TABLE>
 
- ------------------------------------------------------
- ------------------------------------------------------
- ------------------------------------------------------
- ------------------------------------------------------
                                   4,000,000
                              PREFERRED SECURITIES
   
                                 ILLINOIS POWER
                                  FINANCING I

                                % TRUST ORIGINATED
                    PREFERRED SECURITIES SM ("TOPRS SM")
                          GUARANTEED TO THE EXTENT SET
                                FORTH HEREIN BY
                             ILLINOIS POWER COMPANY
    
                            ------------------------
 
                                   PROSPECTUS
                            ------------------------
                              MERRILL LYNCH & CO.
                               SMITH BARNEY INC.
                           DEAN WITTER REYNOLDS INC.
                           A.G. EDWARDS & SONS, INC.
                            PAINEWEBBER INCORPORATED
 
                                           , 1995
 
- ------------------------------------------------------
- ------------------------------------------------------
<PAGE>   39
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.
 
<TABLE>
        <S>                                                                   <C>
        Securities and Exchange Commission registration fee................   $ 34,483*
        New York Stock Exchange listing fees...............................     45,000
        Printing expenses..................................................     75,000
        Legal fees and expenses............................................    115,000
        Independent accountant's fees and expenses.........................     15,000
        Blue Sky and legal investment fees and expenses....................     15,000
        Rating agencies fees and expenses..................................     50,000
        Trustee fees and expenses..........................................     35,000
        Miscellaneous......................................................     15,517
                                                                              --------
             Total.........................................................   $400,000
                                                                              ========
</TABLE>
 
- -------------------------
* Actual. All other expenses are estimated.
 
ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
     Under Section 8.75 of the Illinois Business Corporation Act of 1983, the
Company is empowered, 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 such
person in connection with any threatened, pending or completed action, suit or
proceeding to which such person is made a party or threatened to be made a party
by reason of such person being or having been a director, officer, employee or
agent of the Company, or serving or having served at the request of the Company
as a director, officer, employee or agent of another corporation, partnership,
joint venture, trust or other enterprise. Section 8.75 further provides that
indemnification pursuant to its provisions is not exclusive of other rights of
indemnification to which a person may be entitled under any by-law, agreement,
vote of stockholders or disinterested directors, or otherwise, and that such
indemnification shall continue as to a director, officer, employee or agent of
the Company who has ceased to serve in such capacity, and shall inure to the
benefit of the heirs, executors and administrators of such a person.
 
     The Company's By-Laws provide, in substance, that the Company shall
indemnify any person against expenses (including attorneys' fees), judgments,
fines and amounts paid in settlement actually and reasonably incurred by such
person in connection with any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative, to which
such person is made a party or threatened to be made a party by reason of such
person being or having been a director, officer, employee or agent of the
Company, or serving or having served at the request of the Company in one or
more of the foregoing capacities with another corporation, partnership, joint
venture, trust or other enterprise. The indemnification is not exclusive of
other rights and shall continue as to a person who has ceased to be a director,
officer, employer or agent and shall inure to the benefit of his heirs,
executors and administrators.
 
     The Amended and Restated Declaration of Trust (the "Declaration") provides
that no Trustee, affiliate of any Regular Trustee, or any officers, directors,
shareholders, members, partners, employees, representatives or agents of any
Regular Trustee, or any employee or agent of the Trust or its affiliates (each,
an "Indemnified Person") shall be liable, responsible or accountable in damages
or otherwise to the Trust or any employee or agent of the Trust or its
affiliates for any loss, damage or claim incurred by reason of 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 the authority conferred on such Indemnified Person by the
Declaration or by law, except that an Indemnified Person shall be liable for any
such loss, damage or claim incurred by reason of such Indemnified Person's gross
negligence (or, in the case of the Property Trustee, negligence) or willful
misconduct with respect to such acts or omission. The Declaration
 
                                      II-1
<PAGE>   40
 
also provides that, to the fullest extent permitted by applicable law, the
Company shall indemnify and hold harmless each Indemnified Person from and
against any loss, damage or claim incurred by such Indemnified Person by reason
of 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 the Declaration, 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 gross negligence (or, in the case of the
Property Trustee, negligence) or willful misconduct with respect to such acts or
omissions. The Declaration further provides that, to the fullest extent
permitted by applicable law, expenses (including legal fees) incurred by an
Indemnified Person in defending any claim, demand, action, suit or proceeding
shall, from time to time, be advanced by the Company prior to the final
disposition of such claim, demand, action, suit or proceeding upon receipt by or
an undertaking by or on behalf of the Indemnified Person to repay such amount if
it shall be determined that the Indemnified Person is not entitled to be
indemnified for the underlying cause of action as authorized by the Declaration.
 
     The foregoing rights of indemnification shall apply to any liability of any
director, officer or other Indemnified Person (or his legal representatives)
arising under any of the provisions of the Securities Act, only to the extent
that such rights of indemnification may be determined to be valid by a court of
competent jurisdiction.
 
     The directors and officers of the Company and the Regular Trustees of the
Trust are covered by insurance policies indemnifying against certain
liabilities, including certain liabilities arising under the Securities Act,
which might be incurred by them in such capacities and against which they cannot
be indemnified by the Company or the Trust.
 
     Any agents, dealers or underwriters who execute any of the agreements filed
as Exhibit 1 to this registration statement will agree to indemnify the
Company's directors and their officers and the Regular Trustees of the Trust
against certain liabilities that may arise under the Securities Act with respect
to information furnished to the Company or the Trust by or on behalf of any such
indemnifying party.
 
ITEM 16. LIST OF EXHIBITS.
 
     The exhibits to this Registration Statement are listed in the Exhibit Index
elsewhere herein.
 
ITEM 17. UNDERTAKINGS.
 
     The undersigned registrants hereby undertake:
 
          (1) that for purposes of determining any liability under the
     Securities Act, each filing of the Company's annual report pursuant to
     Section 13(a) or Section 15(d) of the Exchange Act that is incorporated by
     reference in this 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;
 
          (2) that for purposes of determining any liability under the
     Securities Act, 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 Securities Act shall be deemed to be
     part of this Registration Statement as of the time it was declared
     effective; and
 
          (3) that for the purpose of determining any liability under the
     Securities Act, 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.
 
     The undersigned Trust registrant hereby undertakes to provide to the
Underwriters at the closing specified in the Underwriting Agreement certificates
in such denominations and registered in such names as required by the
Underwriters to permit prompt delivery to each purchaser.
 
                                      II-2
<PAGE>   41
 
     Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
registrants pursuant to the provisions referred to in Item 15 above, or
otherwise, the registrants have been advised that in the opinion of the
Commission such indemnification is against public policy as expressed in the
Securities 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 is against public policy as expressed in the Securities Act
and will be governed by the final adjudication of such issue.
 
                                      II-3
<PAGE>   42
 
                                   SIGNATURES
 
   
     Pursuant to the requirements of the Securities Act of 1933, Illinois Power
Company 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 Decatur, and State of Illinois on the 21st day of
November, 1995.
    
                                          ILLINOIS POWER COMPANY
                                                 (Registrant)
 
   
                                          By:      /s/ LARRY F. ALTENBAUMER
    
 
                                            -----------------------------------
   
                                                   Larry F. Altenbaumer
    
   
                                                  Senior Vice President,
    
   
                                                  Chief Financial Officer
    
   
                                                       and Treasurer
    
<PAGE>   43
 
   
     Pursuant to the requirements of the Securities Act of 1933, Illinois Power
Financing 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 Decatur, and State of Illinois on the 21st day of
November, 1995.
    
 
                                          ILLINOIS POWER FINANCING I
                                           (Registrant)
                                            By: Illinois Power Company, as
                                         Sponsor
 
   
                                          By:      /s/ LARRY F. ALTENBAUMER
    
 
                                            -----------------------------------
   
                                                   Larry F. Altenbaumer
    
   
                                                  Senior Vice President,
    
   
                                                  Chief Financial Officer
    
   
                                                       and Treasurer
    
<PAGE>   44
 
                               POWER OF ATTORNEY
 
     KNOW ALL MEN BY THESE PRESENTS, that Illinois Power Company, Illinois Power
Financing I and each of the undersigned officers and directors of Illinois Power
Company hereby constitute and appoint each of Larry D. Haab, Larry F.
Altenbaumer and Cynthia G. Steward the true and lawful attorney-in-fact and
agent of the undersigned, with full power of substitution and resubstitution for
and in the name, place and stead of the undersigned, in any and all capacities,
to sign all or any amendments (including post-effective amendments) of and
supplements to this Registration Statement on Form S-3 and to file the same,
with all exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto each such attorney-in-fact and
agent full power and authority to do and perform each and every act and thing
requisite and necessary to be done in and about the premises, to all intents and
purposes and as fully as said corporation itself and each said officer or
director might or could do in person, hereby ratifying and confirming all that
each such attorney-in-fact and agent, or his 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 on behalf of each of Illinois Power
Company and Illinois Power Financing I by the following persons in their
capacities as officers or directors, as indicated below, of Illinois Power
Company and on the dates indicated.
 
   
<TABLE>
<CAPTION>
              SIGNATURE                               TITLE                        DATE
- -------------------------------------  -----------------------------------  ------------------
<S>                                    <C>                                  <C>
          /s/ LARRY D. HAAB            Chairman, President, Chief
- -------------------------------------  Executive
            Larry D. Haab              Officer and Director
    (Principal Executive Officer)

      /s/ LARRY F. ALTENBAUMER         Senior Vice President, Chief
- -------------------------------------  Financial Officer and Treasurer
        Larry F. Altenbaumer
    (Principal Financial Officer)

       /s/ CYNTHIA G. STEWARD          Controller and Chief
- -------------------------------------  Accounting Officer
         Cynthia G. Steward                                                 
            (Controller)                                                    November 21, 1995

          RICHARD R. BERRY*            Director
- -------------------------------------
          Richard R. Berry

         DONALD E. LASATER*            Director
- -------------------------------------
          Donald E. Lasater

                                       Director
- -------------------------------------
          Donald S. Perkins



    *By:/s/  LARRY F. ALTENBAUMER
        Larry F. Altenbaumer
         as Attorney-in-Fact
</TABLE>
    
 
                                                               
<PAGE>   45
 
   
<TABLE>
<CAPTION>
              SIGNATURE                               TITLE                        DATE
- -------------------------------------  -----------------------------------  ------------------
<S>                                    <C>                                  <C>
          ROBERT M. POWERS*            Director
- -------------------------------------
          Robert M. Powers

          WALTER D. SCOTT*             Director
- -------------------------------------
           Walter D. Scott

         RONALD L. THOMPSON*           Director
- -------------------------------------
         Ronald L. Thompson

          WALTER M. VANNOY*            Director
- -------------------------------------
          Walter M. Vannoy

                                       Director                             November 21, 1995
- -------------------------------------
         Marilou von Ferstel

          CHARLES W. WELLS*            Director
- -------------------------------------
          Charles W. Wells

           JOHN D. ZEGLIS*             Director
- -------------------------------------
           John D. Zeglis

        VERNON K. ZIMMERMAN*           Director
- -------------------------------------
         Vernon K. Zimmerman


    *By:/s/  LARRY F. ALTENBAUMER
        Larry F. Altenbaumer
         as Attorney-in-Fact
</TABLE>
    
 

<PAGE>   46
 
                                 EXHIBIT INDEX
 
   
<TABLE>
<CAPTION>
EXHIBITS                                     DESCRIPTION                                     PAGE
- --------    ------------------------------------------------------------------------------   -----
<S>         <C>                                                                              <C>
 1          Form of Underwriting Agreement.
 4(a)       Certificate of Trust of Illinois Power Financing I.*
 4(b)       Declaration of Trust of Illinois Power Financing I.*
 4(c)       Form of Amended and Restated Declaration of Trust of Illinois Power Financing
            I.*
 4(d)       Form of Indenture between Illinois Power Company and Wilmington Trust Company,
            as Trustee.*
 4(e)       Form of Supplemental Indenture to Indenture to be used in connection with the
            issuance of Subordinated Debentures and Preferred Securities.*
 4(f)       Form of Preferred Security Certificate (contained in the Form of Amended and
            Restated Declaration of Trust of Illinois Power Financing I filed as Exhibit
            4(c) to this Registration Statement).*
 4(g)       Form of Subordinated Debenture (contained in the Form of Supplemental
            Indenture filed as Exhibit 4(e) to this Registration Statement).*
 4(h)       Form of Guarantee Agreement with respect to the Preferred Securities.*
 5(a)       Opinion of Schiff Hardin & Waite.*
 5(b)       Opinion of Richards, Layton & Finger, P.A.*
 8          Tax opinion of Schiff Hardin & Waite (contained in its opinion filed as
            Exhibit 5(a) to this Registration Statement).*
12          Statements of Computations of Ratio of Earnings to Fixed Charges and Ratio of
            Earnings to Combined Fixed Charges and Preferred Stock Dividend Requirements.
23(a)       Consent of Schiff Hardin & Waite (contained in its opinion filed as Exhibit
            5(a) to this Registration Statement).*
23(b)       Consent of Richards, Layton & Finger, P.A. (contained in its opinion filed as
            Exhibit 5(b) to this Registration Statement).*
23(c)       Consent of Price Waterhouse LLP.
24          Powers of Attorney (set forth on the signature page of this Registration
            Statement).*
25(a)       Statement of Eligibility under the Trust Indenture Act of 1939, as amended, of
            Wilmington Trust Company, as Trustee under the Indenture.*
25(b)       Statement of Eligibility under the Trust Indenture Act of 1939, as amended, of
            Wilmington Trust Company, as Trustee under the Amended and Restated
            Declaration of Trust of Illinois Power Financing I.*
25(c)       Statement of Eligibility under the Trust Indenture Act of 1939, as amended, of
            Wilmington Trust Company, as Preferred Securities Guarantee Trustee under the
            Guarantee Agreement with respect to the Preferred Securities.*
</TABLE>
    
 
- -------------------------
   
* Previously filed.
    

<PAGE>   1



                                                                     EXHIBIT 1



                         4,000,000 Preferred Securities

                           ILLINOIS POWER FINANCING I
                               (a Delaware Trust)

             ____% Trust Originated Preferred Securities ("TOPrS")
              (Liquidation Amount of $25 Per Preferred Security) SM


                             UNDERWRITING AGREEMENT

                                  ______, 1995

MERRILL LYNCH & CO.
Merrill Lynch, Pierce, Fenner & Smith Incorporated
  as Representative of the several Underwriters
Merrill Lynch World Headquarters
North Tower
World Financial Center
New York, New York 10281

Ladies and Gentlemen:

          Illinois Power Financing I (the "Trust"), a statutory business trust
organized under the Business Trust Act (the "Delaware Act") of the State of
Delaware (Chapter 38, Title 12, of the Delaware Code, 12 Del. C. Section
Section  3801 et seq.), and Illinois Power Company, an Illinois corporation
(the "Company" and, together with the Trust, the "Offerors") confirm their
agreement (the "Agreement") with Merrill Lynch & Co., Merrill Lynch, Pierce,
Fenner & Smith Incorporated ("Merrill Lynch") and each of the other
Underwriters named in Schedule A hereto (collectively, the "Underwriters",
which term shall also include any underwriter substituted as hereinafter
provided in Section 9 hereof), for whom Merrill Lynch is acting as
representative (in such capacity, Merrill Lynch shall


____________________

SM     "Trust Originated Preferred Securities" and "TOPrS" are service marks of
Merrill Lynch & Co., Inc.


                                       1
<PAGE>   2

hereinafter be referred to as the "Representative"), with respect to the sale
by the Trust and the purchase by the Underwriters, acting severally and not
jointly, of the respective numbers of ____% Trust Originated Preferred
Securities (liquidation amount of $25 per preferred security) of the Trust
("Preferred Securities") set forth in said Schedule A except as may otherwise
be provided in the Pricing Agreement, as hereinafter defined.  The Preferred
Securities will be guaranteed by the Company with respect to distributions and
payments upon liquidation, redemption and otherwise (the "Preferred Securities
Guarantee") pursuant to the Preferred Securities Guarantee Agreement (the
"Preferred Securities Guarantee Agreement"), dated as of ______, 1995, between
the Company and Wilmington Trust Company, as trustee (the "Guarantee Trustee"),
and in certain circumstances described in the Indenture (as defined herein),
the Trust may distribute Subordinated Debt Securities (as defined herein) to
holders of the Preferred Securities.  The Preferred Securities, the related
Preferred Securities Guarantee and $100,000,000 in aggregate principal amount
of the Subordinated Debt Securities are referred to herein as the "Securities".

          Prior to the purchase and public offering of the Preferred Securities
by the several Underwriters, the Offerors and the Representative, acting on
behalf of the several Underwriters, shall enter into an agreement substantially
in the form of Exhibit A hereto (the "Pricing Agreement").  The Pricing
Agreement may take the form of an exchange of any standard form of written
telecommunication between the Offerors and the Representative and shall specify
such applicable information as is indicated in Exhibit A hereto.  The offering
of the Preferred Securities will be governed by this Agreement, as supplemented
by the Pricing Agreement.  From and after the date of the execution and
delivery of the Pricing Agreement, this Agreement shall be deemed to
incorporate the Pricing Agreement.

          The Offerors have filed with the Securities and Exchange Commission
(the "Commission") a registration statement on Form S-3 (No. 33- 63581 and
33-63581-01) and a related preliminary prospectus for the registration under
the Securities Act of 1933, as amended (the "1933 Act") of $100,000,000 in
aggregate amount of a combination of (i) the Preferred Securities, (ii) the
Preferred Securities Guarantee, and (iii) the Subordinated Debt Securities (as
defined below) to be issued and sold to the Trust by the Company.  The Offerors
have filed such amendments thereto, if any, and such amended preliminary
prospectuses as may have been required to the date hereof, and will file such
additional amendments thereto and such amended prospectuses as may hereafter be
required.  Such registration statement (as amended, if applicable) and the
prospectus constituting a part thereof (including, in each case, all documents
incorporated or deemed to be incorporated by reference therein pursuant to Item
12 of Form S-3 under the 1933 Act and the information, if any, deemed to be
part thereof pursuant to Rule 430A(b) of the rules and regulations of the


                                       2
<PAGE>   3

Commission under the 1933 Act (the "1933 Act Regulations")), as from time to
time amended or supplemented pursuant to the 1933 Act, the Securities Exchange
Act of 1934, as amended (the "1934 Act"), or otherwise, are hereinafter
referred to as the "Registration Statement" and the "Prospectus", respectively,
except that, if any revised prospectus shall be provided to the Underwriters by
the Offerors for use in connection with the offering of the Preferred
Securities which differs from the Prospectus on file at the Commission at the
time the Registration Statement becomes effective (whether or not such revised
prospectus is required to be filed by the Offerors pursuant to Rule 424(b) of
the 1933 Act Regulations), the term "Prospectus" shall refer to such revised
prospectus from and after the time it is first provided to the Underwriters for
such use.  All references in this Agreement to financial statements and
schedules and other information that is "contained," "included" or "stated" in
the Registration Statement or the Prospectus (and all other references of like
import) shall be deemed to mean and include all such financial statements and
schedules and other information that are or are deemed to be incorporated by
reference in the Registration Statement or the Prospectus, as the case may be;
and all references in this Agreement to amendments or supplements to the
Registration Statement or the Prospectus shall be deemed to mean and include
the filing of any document under the 1934 Act that is or is deemed to be
incorporated by reference in the Registration Statement or the Prospectus, as
the case may be.

          The Offerors understand that the Underwriters propose to make a
public offering of the Securities as soon as the Representative deems advisable
after the Pricing Agreement has been executed and delivered, and the
Declaration (as defined herein), the Indenture, and the Preferred Securities
Guarantee Agreement have been qualified under the Trust Indenture Act of 1939,
as amended (the "1939 Act").  The entire proceeds from the sale of the
Securities will be combined with the entire proceeds from the sale by the Trust
to the Company of its common securities (the "Common Securities"), as
guaranteed by the Company, to the extent set forth in the Prospectus, with
respect to distributions and payments upon liquidation and redemption (the
"Common Securities Guarantee" and together with the Preferred Securities
Guarantee, the "Guarantees") pursuant to the Common Securities Guarantee
Agreement (the "Common Securities Guarantee Agreement" and, together with the
Preferred Securities Guarantee Agreement, the "Guarantee Agreements"), dated as
of ______, 1995, of the Company, and will be used by the Trust to purchase the
$103,100,000 of ____% subordinated debt securities (the "Subordinated Debt
Securities") issued by the Company.  The Preferred Securities and the Common
Securities will be issued pursuant to the amended and restated declaration of
trust of the Trust, dated as of the Closing Time (the "Declaration"), among the
Company, as Sponsor, Larry F. Altenbaumer and Daniel L. Mortland (the "Regular
Trustees") and Wilmington Trust Company,



                                       3
<PAGE>   4

a Delaware banking corporation, as property trustee (the "Property Trustee and,
together with the Regular Trustees, the "Trustees").  The Subordinated Debt
Securities will be issued pursuant to an indenture, dated as of ________ __,
1995 (the "Base Indenture"), between the Company and Wilmington Trust Company,
as Trustee (the "Debt Trustee"), and a supplement to the Base Indenture, dated
as of ________ __, 1995 (the "Supplemental Indenture," and together with the
Base Indenture and any other amendments or supplements thereto, the
"Indenture"), between the Company and the Debt Trustee.

          Section I.  Representations and Warranties.

          The Offerors jointly and severally represent and warrant to each
Underwriter as of the date hereof and as of the date of the Pricing Agreement
(such latter date being hereinafter referred to as the "Representation Date")
as follows.

               (i)  The Company and the Trust meet, and at the respective times
     of commencement and consummation of the offering of the Securities will
     meet, the requirements for use of Form S-3 under the 1933 Act and the 1933
     Act Regulations, and the Registration Statement has been filed with the
     Commission under the 1933 Act; such Registration Statement and any
     post-effective amendment thereto, each in the form heretofore delivered or
     to be delivered to you, and to you for each of the other Underwriters
     (except that copies of the Registration Statement and any post-effective
     amendment delivered to you for each of the other Underwriters need not
     include exhibits but shall include all documents incorporated by reference
     therein), have been declared effective by the Commission in such form; no
     other document included or incorporated by reference in the Registration
     Statement has heretofore been filed, or transmitted for filing, with the
     Commission; and no stop order suspending the effectiveness of such
     Registration Statement has been issued and no proceeding for that purpose
     has been initiated or threatened by the Commission.

               (ii)      The documents incorporated by reference in the
     Registration Statement or Prospectus, when they became effective or were
     filed with the Commission, as the case may be, conformed in all material
     respects to the requirements of the 1933 Act or the 1934 Act, as
     applicable, and the 1933 Act Regulations and the rules and regulations of
     the Commission under the 1934 Act (the "1934 Act Regulations") and as of
     such time none of such documents contained an untrue statement of a
     material fact or omitted to state a material fact required to be stated
     therein or necessary to make the statements therein, in the light of the
     circumstances under  which they were made, not misleading; and any

                                       4
<PAGE>   5

     further documents so filed and incorporated by reference in the
     Prospectus, or any further amendment or supplement thereto, when such
     documents become effective or are filed with the Commission, as the case
     may be, will conform in all material respects to the  requirements of the
     1933 Act or the 1934 Act, as applicable, and the 1933 Act Regulations and
     the 1934 Act Regulations and will not  contain an untrue statement of a
     material fact or omit to state a material fact required to be stated
     therein or necessary to make the statements therein, in the light of the
     circumstances under which they were made, not misleading; provided,
     however, that this representation and warranty shall not apply to any
     statements or omissions made in reliance upon and in conformity with
     information furnished in writing to the Trust or the Company by an
     Underwriter through you expressly for use in the Prospectus.

               (iii)     Each preliminary prospectus, at the time of filing
     thereof, conformed in all material respects to the requirements of the
     1933 Act and the 1933 Act Regulations and did not contain an untrue
     statement of a material fact or omit to state a material fact required to
     be stated therein or necessary to make the statements therein, in the
     light of the circumstances under which they were made, not misleading;
     provided, however, that this representation and warranty shall not apply
     to any statements or omissions made in reliance upon and in conformity
     with information furnished in writing to the Trust or the Company by an
     Underwriter through you expressly for use therein.

               (iv)      The Registration Statement and the Prospectus conform,
     and, to the extent used to confirm sales of the Securities, any further
     amendments or supplements to the Registration Statement or the Prospectus,
     when any such post-effective amendments are declared effective or
     supplements are filed with the Commission, as the case may be, will
     conform, in all material respects to the requirements of the 1933 Act, the
     1939 Act and the rules and regulations of the Commission thereunder (the
     "1939 Act Regulations") and do not and will not, (i) as of the applicable
     effective date as to the Registration Statement and any amendment thereto
     and (ii) as of the applicable filing date as to the Prospectus, as it may
     be further amended or supplemented, contain an untrue statement of a
     material fact or omit to state a material fact necessary in order to make
     the statements therein, in the light of the circumstances under which they
     were made, not misleading; provided, however, that neither the Company nor
     the Trust makes any representations and warranties as to (A) that part of
     the Registration Statement which shall constitute the Statement of
     Eligibility (Form T-1) under the Trust Indenture Act (the "Form T-1"), or
     (B) the information contained in or omitted from the Registration
     Statement or the


                                       5
<PAGE>   6

     Prospectus in reliance upon and in conformity with information furnished
     in writing to the Trust or the Company by an Underwriter  through you
     expressly for use therein.

               (v)  The Trust has no subsidiaries.  Neither the Trust, the
     Company nor any of the Company's other subsidiaries has sustained, since
     the date of the latest audited financial statements included or
     incorporated by reference in the Prospectus, any material loss or
     interference with its business from fire, explosion, flood or other
     calamity, whether or not covered by insurance, or from any labor dispute
     or court or governmental action, order or decree, otherwise than as set
     forth or contemplated in the Prospectus, and, since the respective dates
     as of which information is given in the Registration Statement and the
     Prospectus there has not been any material change in the capital stock or
     long-term debt of the Company or any of its subsidiaries (determined on a
     consolidated basis) or any material adverse change, or any development
     involving a prospective material adverse change, in or affecting the
     general affairs, management, financial position, stockholders' equity or
     results of operations of the Company and its subsidiaries (taken as a
     whole), otherwise than as set forth or contemplated in the Prospectus.

               (vi)      The Order of the Illinois Commerce Commission (the
     "ICC") approving the investment by the Company in the Common Securities in
     connection with the issue and sale of the Preferred Securities, the
     issuance of the Subordinated Debt Securities and the execution of the
     Guarantees (the "Order") has been duly issued and remains in full force
     and effect without amendment or modification, and is not the subject of
     any appeal or other proceeding.

               (vii)     The Trust has been duly created and is validly
     existing in good standing as a business trust under the laws of the State
     of Delaware, with power and authority to own its properties and conduct
     its business as described in the Prospectus, and  has been duly qualified
     for the transaction of business and is in good standing under the laws of
     each jurisdiction in which it owns or  leases properties or conducts any
     business, so as to require such qualification, or is subject to no
     material liability or disability  by reason of the failure to be so
     qualified in any such jurisdiction.  The Trust is and will be classified
     for United States federal  income tax purposes as a grantor trust and not
     as an association taxable as a corporation.

               (viii)    The Company has been duly incorporated and is validly
     existing as a corporation in good standing under the laws of the State of
     Illinois, with power and authority (corporate and other) to own its

                                       6
<PAGE>   7

     properties and conduct its business as described in the Prospectus and has
     been duly qualified as a foreign corporation for the transaction of
     business and is in good standing under the laws of each other jurisdiction
     in which it owns or leases properties or conducts any business, so as to
     require such qualification, or is subject to no material liability or
     disability by reason of the failure to be so qualified in any such
     jurisdiction; and each subsidiary of the Company (other than the Trust and
     Illinois Power Capital, L.P.) has been duly incorporated and is validly
     existing as a corporation in good standing under the laws of its
     jurisdiction of incorporation.

               (ix)      The Company has no significant subsidiaries within the
     meaning of Regulation S-X.  All of the outstanding shares of common stock
     of the Company are owned by Illinova Corporation, an Illinois corporation
     (the "Parent").

               (x)       The Preferred Securities have been duly and validly
     authorized and, when issued and delivered against payment therefor as
     provided herein, in the Pricing Agreement and in the Declaration, will be
     duly and validly issued and fully paid and nonassessable undivided
     beneficial interests in the assets of the Trust and will conform as to
     legal matters to the description thereof contained in the Prospectus.

               (xi)      The issuance and delivery of the Subordinated Debt
     Securities have been duly authorized and, when issued and delivered and
     when the Subordinated Debt Securities have been duly executed,
     authenticated, issued and delivered in accordance with this Agreement and
     the Pricing Agreement, the Indenture and the Subordinated Debt Securities
     will constitute valid and legally binding obligations of the Company
     entitled to the benefits provided by the Indenture; subject, as to
     enforcement, to bankruptcy, insolvency, reorganization and other laws of
     general applicability relating to or affecting creditors' rights and to
     general equity principles; the Indenture will have been duly authorized,
     executed and delivered and, at Closing Time (as defined below), the
     Indenture will be duly qualified under the 1939 Act and will constitute a
     valid and legally binding obligation of the Company, enforceable in
     accordance with its terms, subject, as to enforcement, to bankruptcy,
     insolvency, reorganization and other laws of general applicability
     relating to or affecting creditors' rights and to general equity
     principles; the Subordinated Debt Securities and the Indenture will
     conform as to legal matters to the descriptions thereof in the Prospectus;
     and the Indenture will be substantially in the form filed as an exhibit to
     the Registration Statement.



                                       7
<PAGE>   8


               (xii)     The Declaration has been duly authorized by the
     Company and at Closing Time, will have been duly executed and delivered by
     the Company and the Trustees, and assuming due authorization, execution
     and delivery by the Property Trustee (as defined in the Declaration), the
     Declaration will, at Closing Time, be a valid and binding obligation of
     the Company and the Regular Trustees, enforceable against the Company and
     the Regular Trustees in accordance with its terms, subject, as to
     enforcement, to bankruptcy, insolvency, reorganization, and other laws of
     general applicability relating to or affecting creditors' rights and to
     general equity principles; and at Closing Time, the Declaration will have
     been duly qualified under the 1939 Act.

               (xiii)    Each of the Guarantee Agreements has been duly
     authorized by the Company and, when executed and delivered by the Company,
     and in the case of the Preferred Securities Guarantee Agreement, assuming
     due authorization, execution and delivery of the Preferred Securities
     Guarantee by the Guarantee Trustee, will constitute a valid and binding
     obligation of the Company, enforceable in accordance with its terms,
     subject, as to enforcement, to bankruptcy, insolvency, reorganization and
     other laws of general applicability relating to or affecting creditors'
     rights and to general equity principles; each of the Guarantees and the
     Guarantee Agreements will conform as to legal matters to the description
     thereof in the Prospectus; and the Preferred Securities Agreement, at
     Closing Time, will have been duly qualified under the 1939 Act.

               (xiv)     The Common Securities have been duly authorized by the
     Declaration and, when issued and delivered by the Trust to the Company
     against payment therefor as described in the Registration Statement and
     Prospectus, will be validly issued and fully paid and, except as otherwise
     provided in Section 10.1(b) of the Declaration, nonassessable undivided
     beneficial interests in the assets of the Trust and will conform as to
     legal matters to the descriptions thereof in the Prospectus.  The issuance
     of the Common Securities is not subject to preemptive or other similar
     rights; and at Closing Time all of the issued and outstanding Common
     Securities of the Trust will be directly owned by the Company free and
     clear of any security interest, mortgage, pledge, lien, encumbrance, claim
     or equity.

               (xv)      Each of the Regular Trustees of the Trust is an
     employee of the Company and has been duly authorized by the Company to
     execute and deliver the Declaration.



                                       8
<PAGE>   9


               (xvi)     The Trust is not in violation of its Certificate of
     Trust or the Declaration, or in default in the performance or observance
     of any material obligation, agreement, covenant or condition contained in
     any contract, agreement or other instrument to which it is a party or by
     which it may be bound, the effect of which is material to the Trust, and
     neither the execution or delivery of this Agreement or the Pricing
     Agreement, the consummation of the transactions herein contemplated, the
     fulfillment of the terms hereof or the terms of the Pricing Agreement, nor
     compliance with the terms and provisions hereof or of the Pricing
     Agreement will conflict with, or result in a breach or violation of, or
     constitute a default under (i) its Certificate of Trust or the
     Declaration, or any contract, agreement or other instrument to which the
     Trust is a party or by which it may be bound or (ii) any statute, order,
     rule or regulation applicable to the Trust of any court or any federal or
     state governmental agency or body having jurisdiction over the Trust or
     over any of its properties; and no consent, approval, authorization,
     order, registration or qualification of or with any such court or
     governmental agency or body is required solely as a result of the issuance
     and sale or delivery by the Trust of the Preferred Securities pursuant to
     this Agreement or the Pricing Agreement, the execution, delivery and
     performance by the Trust of this Agreement or the Pricing Agreement, or
     the consummation of the transactions contemplated in this Agreement or the
     Pricing Agreement, except as set forth in Section l(vi) above and except
     for the registration under the 1933 Act of the Securities, the
     qualification of the Declaration, the Indenture and the Preferred
     Securities Guarantee Agreement under the 1939 Act and such consents,
     approvals, authorizations, registrations or qualifications as may be
     required under state securities or Blue Sky laws in connection with the
     purchase of the Preferred Securities and the distribution of the
     Securities by the Underwriters.

               (xvii)    The Company is not in violation of its Amended and
     Restated Articles of Incorporation, as amended (the "Restated Articles"),
     or its By-Laws, as amended (the "By-Laws"), or in default in the
     performance or observance of any material obligation, agreement, covenant
     or condition contained in any contract, agreement or other instrument to
     which it is a party or by which it may be bound, the effect of which is
     material to the Company, and neither the execution or delivery of this
     Agreement or of the Pricing Agreement, the consummation of the
     transactions herein contemplated or in the Pricing Agreement, the
     fulfillment of the terms hereof or of the Pricing Agreement, nor
     compliance with the terms and provisions hereof or the terms and
     provisions of the Pricing Agreement will conflict with, or result in a
     breach or violation of, or constitute a default under (i) the Restated
     Articles, the By-Laws, or any contract, agreement or other instrument to



                                       9
<PAGE>   10

     which the Company is a party or by which it may be bound or (ii) any
     statute, order, rule or regulation applicable to the Company of  any court
     or any federal or state governmental agency or body having jurisdiction
     over the Company or over its properties; and no  consent, approval,
     authorization, order, registration or qualification of or with any such
     court or governmental agency or body is  required for the issuance and
     sale or delivery of the Preferred Securities or the consummation by the
     Company of the transactions contemplated by this Agreement or by the
     Pricing Agreement, except as set forth in Section l(vi) above and except
     for the registration under the 1933 Act of the Securities, the
     qualification of the Declaration, the Indenture and the Preferred
     Securities Guarantee  Agreement under the 1939 Act and such consents,
     approvals, authorizations, registrations or qualifications as may be
     required under  state securities or Blue Sky laws in connection with the
     purchase of the Preferred Securities and the distribution of the
     Securities by  the Underwriters.

               (xviii)   Other than as set forth in the Prospectus, there are
     no legal or governmental proceedings pending to which the Company or any
     of its subsidiaries is a party or of which any property of the Company or
     any of its subsidiaries is the subject which, if determined adversely to
     the Company or any of its subsidiaries, would individually or in the
     aggregate have a material adverse effect on the consolidated position,
     stockholders' equity or results of operations of the Company and its
     subsidiaries taken as a whole; and, to the best of the Company's
     knowledge, no such proceedings are threatened or contemplated by
     governmental authorities or threatened by others.

               (xix)     Price Waterhouse LLP, who have audited certain
     financial statements of the Company and its other subsidiaries, are
     independent certified public accountants with respect to the Company as
     required by the 1933 Act and the 1933 Act Regulations.

               (xx)      There are no contracts or documents of the Trust or
     the Company or any of the Company's subsidiaries that are required to be
     filed as exhibits to the Registration Statement or to any of the documents
     incorporated by reference therein by the 1933 Act, the 1933 Act
     Regulations, the 1939 Act, the 1939 Act Regulations, the 1934 Act or the
     1934 Act Regulations that have not been so filed.

               (xxi)     There are no contracts, agreements or understandings
     between the Trust or the Company and any person granting such person the
     right to require the Trust or the Company to file a registration statement
     under the 1933 Act with respect to any undivided beneficial


                                       10
<PAGE>   11

     interest of the Trust or any preferred stock of the Company owned or to be
     owned by such person or to require the Trust or the Company  to include
     such securities in the securities registered pursuant to the Registration
     Statement or in any securities being registered  pursuant to any other
     registration statement filed by the Trust or the Company under the 1933
     Act.

               (xxii)    Neither the Trust nor the Company nor any of the
     Company's other subsidiaries is and, after giving effect to the offering
     and sale of the Preferred Securities, will be an "investment company" or
     an entity "controlled" by an "investment company," as such terms are
     defined in the Investment Company Act of 1940, as amended (the "1940
     Act").

               (xxiii)   The Trust is not a "holding company" within the
     meaning of the Public Utility Holding Company Act of 1935, as amended
     ("1935 Act"); the Parent is a "holding company" as defined in 1935 Act by
     reason of its ownership of all the outstanding shares of common stock of
     the Company, and the Company is a "holding company," but the Company and
     Parent are each exempt from 1935 Act, except for the provisions of Section
     9(a)(2) thereof, by virtue of Section 3(a)(2) thereof and Section 3(a)(1)
     thereof and Rule 2 thereunder, respectively.

          Section 2.     Sale and Delivery to Under-
                              writers; Closing.

          (a)  On the basis of the representations and warranties herein
     contained and subject to the terms and conditions herein set forth, the
     Trust agrees to sell to each Underwriter, severally and not jointly, and
     each Underwriter, severally and not jointly, agrees to purchase from the
     Trust, at the price per security set forth in the Pricing Agreement, the
     number of Preferred Securities set forth in Schedule A opposite the name
     of such Underwriter (except as otherwise provided in the Pricing
     Agreement), plus any additional number of Preferred Securities that such
     Underwriter may become obligated to purchase pursuant to the provisions of
     Section 9 hereof.

          The purchase price per security to be paid by the several
     Underwriters for the Preferred Securities shall be an amount equal to the
     initial public offering price.  The initial public offering price per
     Preferred Security shall be a fixed price to be determined by agreement
     between the Representative and the Offerors.  The initial public offering
     price and the purchase price, when so determined, shall be set forth in
     the Pricing Agreement.  In the event that such prices have not been agreed
     upon and

                                       11
<PAGE>   12

     the Pricing Agreement has not been executed and delivered by all parties
     thereto by the close of business on the fourth business day following the
     date of this Agreement, this Agreement shall terminate forthwith, without
     liability of any party to any other party,  unless otherwise agreed to by
     the Offerors and the Representative.  As compensation to the Underwriters
     for their commitments hereunder  and in view of the fact that the proceeds
     of the sale of the Preferred Securities will be used to purchase the
     Subordinated Debt  Securities of the Company, the Company hereby agrees to
     pay at Closing Time to the Representative, for the accounts of the several
     Underwriters, a commission per Preferred Security determined by agreement
     between the Representative and the Company for the Preferred Securities to
     be delivered by the Trust hereunder at Closing Time.  The commission, when
     so determined, shall be set forth in the  Pricing Agreement.

          (b)  Payment of the purchase price for, and delivery of certificates
     for, the Preferred Securities shall be made at the office of Reid & Priest
     LLP, or at such other place as shall be agreed upon by the Representative
     and the Trust, at 10:00 A.M. New York time on the third business day
     (unless postponed in accordance with the provisions of Section 9) after
     execution of the Pricing Agreement, or such other time not later than ten
     business days after such date as shall be agreed upon by the
     Representative, the Trust, the Company (such time and date of payment and
     delivery being herein called "Closing Time").  Payment shall be made to
     the Trust by certified or official bank check or checks drawn in New York
     Clearing House funds or similar next day funds payable to the order of the
     Trust to an account designated by the Trust, against delivery to the
     Representative for the respective accounts of the Underwriters of
     certificates for the Preferred Securities to be purchased by them.
     Certificates for the Preferred Securities shall be in such  denominations
     and registered in such names as the Representative may request in writing
     at least two business days before the Closing  Time.  It is understood
     that each Underwriter has authorized the Representative, for its account,
     to accept delivery of, receipt for,  and make payment of the purchase
     price for, the Preferred Securities which it has agreed to purchase.
     Merrill Lynch, individually and  not as Representative of the
     Underwriters, may (but shall not be obligated to) make payment of the
     purchase price for the Preferred Securities to be purchased by any
     Underwriter whose check has not been received by the Closing Time, but
     such payment shall not relieve such Underwriter from its obligations
     hereunder.


                                       12
<PAGE>   13

     The certificate(s) for the Preferred Securities will be made available for
examination and packaging by the Representative not later than 10:00 A.M. on
the last business day prior to the Closing Time.

     At the Closing Time, the Company will pay, or cause to be paid, the
commission payable at such time to the Underwriters under Section 2 hereof by
certified or official bank check or checks payable to Merrill Lynch, Pierce,
Fenner & Smith Incorporated in New York Clearing House funds or other similar
next day funds.


          Section 3.  Covenants of the Offerors.  Each of the Offerors jointly
and severally covenant with each Underwriter as follows:

          (a)  The Offerors will notify the Representative immediately, and
     confirm the notice in writing, (i) of the effectiveness of the
     Registration Statement and any amendment thereto (including any
     post-effective amendment), (ii) of the receipt of any comments from the
     Commission, (iii) of any request by the Commission for any amendment to
     the Registration Statement or any amendment or supplement to the
     Prospectus or for additional information, and (iv) of the issuance by the
     Commission of any stop order suspending the effectiveness of the
     Registration Statement or the initiation of any proceedings for that
     purpose.  The Offerors will make every reasonable effort to prevent the
     issuance of any stop order and, if any stop order is issued, to obtain the
     lifting thereof at the earliest possible moment.

          (b)  The Offerors will give the Representative notice of their
     intention to file or prepare (i) any amendment to the Registration
     Statement (including any post-effective amendment), (ii) any amendment or
     supplement to the Prospectus (including any revised prospectus which the
     Offerors propose for use by the Underwriters in connection with the
     offering of the Preferred Securities which differs from the prospectus on
     file at the Commission at the time the Registration Statement became
     effective, whether or not such revised prospectus is required to be filed
     pursuant to Rule 424(b) of the 1933 Act Regulations), or (iii) any
     document that would as a result thereof be incorporated by reference in
     the Prospectus whether pursuant to the 1933 Act, the 1934 Act or
     otherwise, will furnish the Representative with copies of any such
     amendment, supplement or other document a reasonable amount of time prior
     to such proposed filing or use, as the case may be, and will not file any
     such amendment, supplement or other document or use any such prospectus to
     which the Representative or counsel for the Underwriters shall reasonably
     object.  Subject to the foregoing, the Offerors will


                                       13
<PAGE>   14

     promptly prepare a supplement to the Prospectus to reflect the terms of
     the Preferred Securities and the terms of the offering.  The Offerors will
     file the Prospectus as so supplemented pursuant to Rule 424(b) of the 1933
     Act Regulations not later than the  Commission's close of business on the
     second business day following the execution and delivery of this
     Agreement, or, if applicable,  such earlier time as may be required by
     Rule 430A(a)(3) of the 1933 Act Regulations.

          (c)  The Offerors will deliver to the Representative one signed copy
     of the Registration Statement as originally filed and of each amendment
     thereto (including exhibits filed therewith or incorporated by reference
     therein and documents incorporated or deemed to be incorporated by
     reference therein) and will also deliver to the Representative a conformed
     copy of the Registration Statement as originally filed and of each
     amendment thereto (without exhibits) for each of the Underwriters.

          (d)  The Offerors will furnish to each Underwriter, from time to time
     during the period when the Prospectus is required to be delivered under
     the 1933 Act, such number of copies of the Prospectus (as amended or
     supplemented) as such Underwriter may reasonably request for the purposes
     contemplated by the 1933 Act or the 1933 Act Regulations.

          (e)  If at any time when the Prospectus is required by the 1933 Act
     to be delivered in connection with sales of the Preferred Securities, any
     event shall occur as a result of which it is necessary, in the opinion of
     counsel for the Underwriters or counsel to the Company and the Trust, to
     amend or supplement the Prospectus in order to make the Prospectus not
     misleading in the light of the circumstances existing at the time it is to
     be delivered to a purchaser, or if it shall be necessary at any such time,
     to amend the Registration Statement or amend or supplement the Prospectus
     in order to comply with the requirements of the 1933 Act or the 1933 Act
     Regulations, the Offerors will promptly prepare and file with the
     Commission, subject to paragraph (b) above, such amendment or  supplement
     as may be necessary to correct such untrue statement or omission or to
     make the Registration Statement or the Prospectus  comply with such
     requirements; and the Offerors will furnish to the Underwriters a
     reasonable number of copies of such amendment or  supplement.

          (f)  The Offerors will endeavor, in cooperation with the
     Underwriters, to qualify the Preferred Securities (including the Preferred
     Securities Guarantee with respect thereto) and the Subordinated Debt
     Securities for offering and sale under the applicable securities laws of


                                       14
<PAGE>   15

     such states and the other jurisdictions of the United States as the
     Representative may designate; provided, however, that none of the Offerors
     shall be obligated to qualify as a foreign corporation in any jurisdiction
     in which it is not so qualified.

          (g)  The Trust will make generally available to its security holders
     as soon as practicable but not later than 45 days after the close of the
     period covered thereby, an earnings statement of the Company (in form
     complying with the provisions of Rule 158 of the 1933 Act Regulations)
     covering a twelve-month period beginning not later than the first day of
     the Trust's fiscal quarter next following the "effective date" (as defined
     in said Rule 158) of the Registration Statement.

          (h)  For a period of five years after the Closing Time, the Company
     will furnish to you and, upon request, to each Underwriter, copies of all
     annual reports, quarterly reports and current reports filed with the
     Commission on Forms 10-K, 10-Q and 8-K, or such other similar forms as may
     be designated by the Commission, and such other documents, reports and
     information as shall be furnished by the Company to its stockholders or
     security holders generally.

          (i)  The Offerors will use best efforts to effect the listing of the
     Preferred Securities (including the Preferred Securities Guarantee with
     respect thereto) on the New York Stock Exchange; if the Preferred
     Securities are exchanged for Subordinated Debt Securities, the Company
     will use its best efforts to effect the listing of the Subordinated Debt
     Securities on the exchange on which the Preferred Securities were then
     listed.

          (j)  During a period of 30 days from the date of the Pricing
     Agreement, neither the Trust nor the Company will, without the
     Representative's prior written consent, 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 the Subordinated Debt
     Securities or any debt securities substantially similar to the
     Subordinated Debt Securities or equity securities substantially similar to
     the Preferred Securities (except for the Subordinated Debt Securities and
     the Preferred Securities issued in accordance with this Agreement).


          Section 4.  Payment of Expenses.  The Company will pay all expenses
incident to the performance of each Offerors' obligations under this Agreement,
including, but not limited to, (i) the printing and filing of the


                                       15
<PAGE>   16

     Registration Statement as originally filed and of each amendment thereto,
     (ii) the printing of this Agreement and the Pricing Agreement, (iii) the
     preparation, issuance and delivery of the certificates for the Preferred
     Securities to the Underwriters, (iv) the fees and disbursements of the
     Company's and the Trust's counsel and accountants, (v) the qualification
     of the Preferred Securities, the Preferred Securities Guarantee and the
     Subordinated Debt Securities under securities laws in accordance with the
     provisions of Section 3(f) hereof, including filing fees and the fees and
     disbursements of counsel for the Underwriters in connection therewith and
     in connection with the preparation of any Blue Sky survey and any legal
     investment survey, (vi) the printing and delivery to the Underwriters of
     copies of the Registration Statement as originally filed and of each
     amendment thereto, of each preliminary prospectus, and of the Prospectus
     and any amendments or supplements thereto, (vii) the printing and delivery
     to the Underwriters of copies of any Blue Sky survey and any legal
     investment survey, (viii) the fee of the National Association of
     Securities Dealers, Inc., (ix) the fees and expenses of the Debt Trustee,
     including the fees and disbursements of counsel for the Debt Trustee in
     connection with the Indenture and the Subordinated Debt Securities, (x)
     the fees and expenses of the Property Trustee, and the Guarantee Trustee,
     including the fees and disbursements of counsel for the Property Trustee
     in connection with the Declaration and the Certificate of Trust, (xi) any
     fees payable in connection with the rating of the Preferred Securities and
     the Subordinated Debt Securities, (xii) the fees and expenses incurred in
     connection with the listing of the Preferred Securities (and the related
     Preferred Securities Guarantee) and, if applicable, the Subordinated Debt
     Securities on the New York Stock Exchange, (xiii) the cost and charges of
     any transfer agent or registrar, and (xiv) the cost of qualifying the
     Preferred Securities with The Depository Trust Company.

          If this Agreement is terminated by the Representative in accordance
     with the provisions of Section 5 or Section 8 hereof, the Company shall
     reimburse the Underwriters for all of their reasonable out-of-pocket
     expenses, including the reasonable fees and disbursements of counsel for
     the Underwriters.


          Section 5.  Conditions of Underwriters' Obligations.  The obligations
     of the Underwriters hereunder are subject to the accuracy of the
     representations and warranties of the Offerors herein contained, to the
     performance by the Offerors of their obligations hereunder, and to the
     following further conditions:

         (a)  The Registration Statement shall have become effective not later 
     than 5:30 P.M. on the date hereof, or with the consent of the 
     Representative, at a later time and date, not later, however, than 5:30 


                                       16
<PAGE>   17

     P.M. on the first business day following the date hereof, or at such
     later time and date as may be approved by the Representative; and at
     Closing Time no stop order suspending the effectiveness of the
     Registration Statement shall have been issued under the 1933 Act or
     proceedings therefor initiated or threatened by the Commission.  The
     Prospectus shall have been filed with the Commission pursuant to Rule
     424(b) within the applicable time period prescribed for such filing
     by the 1933 Act Regulations and in accordance with Section 3(b) and prior
     to Closing Time the Offerors shall have provided evidence satisfactory to
     the Representative of such timely filing.

          (b)  At Closing Time the Representative shall have received:

                    (1)  The favorable opinion, dated as of Closing Time, of
          Schiff Hardin & Waite, counsel for the Offerors in form and substance
          satisfactory to counsel for the Underwriters, to the effect that:

               (i)  The Trust has been duly created and is validly existing in
     good standing as a business trust under the Delaware Act; all filings
     required under the laws of the State of Delaware with respect to the
     formation and valid existence of the Trust as a business trust have been
     made; the Trust is duly qualified for the transaction of business and is
     in good standing under the laws of each jurisdiction in which it owns or
     leases properties or conducts any business, except to the extent that the
     failure to so qualify or be in good standing would not have a material
     adverse effect on the Trust.

               (ii)  The Company has been duly incorporated and is validly
     existing as a corporation in good standing under the laws of the State of
     Illinois, with power and authority (corporate and other) to own its
     properties and conduct its business as described in the Prospectus and has
     been duly qualified as a foreign corporation for the transaction of
     business and is in good standing under the laws of each other jurisdiction
     in which it owns or leases properties or conducts any business, so as to
     require such qualification, or is subject to no material liability or
     disability by reason of the failure to be so qualified in any such
     jurisdiction (such counsel being entitled to rely in respect of the
     opinion in the foregoing clause upon opinions of local counsel and in
     respect of matters of fact upon certificates of officers of the Company,
     provided that such counsel shall state that he believes that both you and
     he are justified in relying upon such opinions and certificates).

               (iii)  All of the Common Securities have been duly authorized by
     the Declaration and are duly and validly issued, are fully paid and,


                                       17
<PAGE>   18

     except as otherwise provided in Section 10.1(b) of the Declaration,
     nonassessable undivided beneficial interests in the assets of the Trust
     and are owned by the Company, free and clear of all liens, encumbrances,
     equities or claims; the Common Securities conform as to legal matters to
     the description thereof in the Prospectus; and the Trust is not a party to
     or otherwise bound by any agreement other than this Agreement, the Pricing
     Agreement, the Declaration and the agreements contemplated by the
     Prospectus.

               (iv)      To the best knowledge of such counsel there is no
     pending or threatened action, suit or proceeding before any court or
     governmental agency, authority or body or any arbitrator involving the
     Trust, the Company or any of the Company's subsidiaries or any property of
     the Company or any of its subsidiaries, of a character required to be
     disclosed in the Registration Statement which is not adequately disclosed
     in the Prospectus, and there is no contract or other document of a
     character required to be described in the Registration Statement or
     Prospectus, or to be filed as an exhibit, which is not described in the
     Prospectus or filed as required; and the statements included or
     incorporated in the Prospectus describing any legal proceedings or
     material contracts or agreements relating to the Trust or the Company
     fairly summarize such matters.

               (v)       The Preferred Securities have been validly issued and,
     subject to the qualifications set forth herein, are fully paid and
     nonassessable undivided beneficial interests in the assets of the Trust;
     the holders of the Preferred Securities will be entitled to the same
     limitation of personal liability under Delaware law as is extended to
     stockholders of private corporations for profit; and the issuance of the
     Preferred Securities is not subject to preemptive or other similar rights.
     Said counsel may note that the holders of the Preferred Securities may be
     obligated, pursuant to the Declaration, to (a) provide indemnity and/or
     security in connection with, and pay taxes or governmental charges arising
     from, transfers or exchanges of Preferred Securities certificates and the
     issuance of replacement Preferred Securities certificates and (b) provide
     security and indemnity in connection with requests of or directions to the
     Property Trustee to exercise its rights and remedies under the
     Declaration.  The Preferred Securities conform as to legal matters to the
     descriptions thereof in the Prospectus.

               (vi)      The issuance and delivery of the Subordinated Debt
     Securities have been duly authorized, and the Subordinated Debt Securities
     have been duly executed, authenticated, issued and delivered in accordance
     with the Indenture, and the Subordinated Debt Securities


                                       18
<PAGE>   19

     constitute valid and legally binding obligations of the Company entitled
     to the benefits provided by the Indenture; subject, as to enforcement, to
     bankruptcy, insolvency, reorganization and other laws of general
     applicability relating to or affecting creditors' rights and to general
     equity principles.  The Indenture has been duly authorized, executed and
     delivered and has been duly qualified under the 1939 Act and constitutes a
     valid and legally binding obligation of the Company, enforceable in
     accordance with its terms, subject, as to enforcement, to bankruptcy,
     insolvency, reorganization and other laws of general applicability
     relating to or affecting creditors' rights and to general equity
     principles.  The Subordinated Debt Securities and the Indenture conform as
     to legal matters to the descriptions thereof in the Prospectus.

               (vii)     The issuance of each of the Guarantee Agreements has
     been duly authorized, executed and delivered and the Preferred Securities
     Guarantee constitutes a valid and legally binding obligation of the
     Company, enforceable in accordance with its terms, subject, as to
     enforcement, to bankruptcy, insolvency, reorganization and other laws of
     general applicability relating to or affecting creditors' rights and to
     general equity principles.  The Preferred Securities Guarantee Agreement
     has been duly qualified under the 1939 Act.  The Guarantees and the
     Guarantee Agreements conform as to legal matters to the descriptions
     thereof in the Prospectus.

               (viii)    The Declaration has been duly authorized, executed and
     delivered by the Company and the Trustees and is a valid and binding
     obligation of the Company and each of the Regular Trustees, enforceable
     against the Company and each of the Regular Trustees in accordance with
     its terms, subject, as to enforcement, to bankruptcy, insolvency,
     reorganization, and other laws relating to or affecting creditors' rights
     and to general equity principles.  The Declaration conforms as to legal
     matters to the description thereof in the Prospectus.

               (ix)      The Declaration has been duly qualified under the 1939
     Act.

               (x)       This Agreement and the Pricing Agreement have been
     duly authorized, executed and delivered by each of the Trust and the
     Company.

               (xi)      The Order has been duly issued and remains in full
     force and effect without amendment or modification, and is not the subject
     of any appeal or other proceeding.


                                       19
<PAGE>   20


               (xii)     The issuance and sale by the Trust of the Preferred
     Securities, the issuance and sale of the Subordinated Debt Securities by
     the Company, the compliance by the Trust and the Company with all of the
     provisions of this Agreement and the Pricing Agreement, the execution,
     delivery and performance by the Company of the Guarantees and
     the consummation of the transactions herein and therein contemplated will
     not conflict with or result in a breach or violation of any of the terms
     or provisions of, or constitute a default under, any agreement or
     instrument known to such counsel to which the Trust or the Company is a
     party or by which the Trust or the Company is bound or to which any of the
     property of the Trust or the Company is subject, the Certificate of Trust
     and the Declaration, the Restated Articles or By-laws of the Company, or
     any statute, order, rule or regulation known to such counsel of any court
     or any federal or state governmental body having jurisdiction over the
     Trust, the Company or any of their properties; and no consent, approval,
     authorization, order, registration or qualification of or with any court
     or governmental agency or body is required solely as a result of the
     issuance, sale or delivery of the Preferred Securities or the consummation
     of the transactions contemplated by this Agreement and the Pricing
     Agreement, except for (i) the Order, (ii) the registration under the 1933
     Act of the Securities, (iii) the qualification of the Indenture, the
     Declaration and the Preferred Securities Guarantee Agreement under the
     1939 Act and (iv) such consents, approvals, authorizations, registrations
     or qualifications as may be required under state securities or Blue Sky
     laws in connection with the purchase of the Preferred Securities and the
     distribution of the Securities by the Underwriters.

               (xiii)    The Trust is not a "holding company" within the
     meaning of the 1935 Act; the Parent is a "holding company" as defined in
     the 1935 Act by reason of its ownership of all the outstanding shares of
     common stock of the Company, and the Company is a "holding company," but
     the Company and the Parent are each exempt from the 1935 Act, except for
     the provisions of Section 9(a)(2) thereof, by virtue of Section 3(a)(2)
     thereof and Section 3(a)(1) thereof and Rule 2 thereunder, respectively.

               (xiv)     Neither the Trust nor the Company is and, after giving
     effect to the offering and sale of the Preferred Securities, will be an
     "investment company" or an entity "controlled" by an "investment company,"
     as such terms are defined in the 1940 Act.

               (xv)      Each part of the Registration Statement, when such
     part became effective, and the Prospectus as of its date and any
     amendments or supplements thereto made by the Company and the Trust 


                                       20
<PAGE>   21

     prior to the Closing Time as of the date of such amendment or supplement
     complied as to form in all material respects with the requirements of the
     1933 Act, the 1933 Act Regulations, the 1939 Act and the 1939 Act
     Regulations; such counsel has no reason to believe that, as of its
     effective date, the Registration Statement or any further amendment
     thereto made by the Company and the Trust prior to the Closing Time 
     contained an untrue statement of a material fact or omitted to state a 
     material fact required to be stated herein or necessary to make the 
     statements therein not misleading or that, as of its date, the Prospectus 
     and any further amendment or supplement thereto made by the Company and 
     the Trust prior to the Closing Time, contained an untrue statement of a
     material fact or omitted to state a material fact necessary to make the 
     statements therein, in the light of the circumstances under which they 
     were made, not misleading, or that, as of the Closing Time, either the 
     Registration Statement or the Prospectus, as amended or supplemented, or 
     any further amendment or supplement thereto made by the Company and the 
     Trust prior to the Closing Time contains an untrue statement of a material
     fact or omits to state a material fact necessary to make the statements 
     therein, in the light of the circumstances under which they were made, 
     not misleading; provided, that such counsel need not express any belief 
     (A) as to the financial statements and related schedules in or 
     incorporated by reference in the Registration Statement and the 
     Prospectus, (B) as to any information contained therein that was 
     furnished to the Trust or the Company in writing by any Underwriter 
     through you expressly for use therein or (C) as to any statements 
     contained in the Form T-1 filed as an exhibit to the Registration 
     Statement; and such counsel does not know of any amendment to the 
     Registration Statement required to be filed or of any contracts or
     other documents of a character required to be filed as an exhibit to the
     Registration Statement or required to be incorporated by reference into
     the Prospectus as amended or supplemented or required to be described in
     the Registration Statement or the Prospectus as amended or supplemented
     which are not filed or incorporated by reference or described as required.

               (xvi)     The documents incorporated by reference in the
     Prospectus or any amendment or supplement thereto (other than the
     financial statements and related schedules therein, as to which such
     counsel need express no opinion), when they became effective under the
     1933 Act or were filed with the Commission under the 1934 Act, as the case
     may be, complied as to form in all material respects with the requirements
     of the 1933 Act or the 1934 Act, as applicable, and the 1933 Act
     Regulations and the 1934 Act Regulations; and such counsel has no reason
     to believe that any of such documents, when such documents



                                       21
<PAGE>   22

         became effective or were so filed, as the case may be,
         contained, in the case of a registration statement which became
         effective under the 1933 Act, an untrue statement of a material fact
         or omitted to state a material fact required to be stated therein or
         necessary to make the statements therein, in the light of the
         circumstances under which they were made, not misleading, or, in the
         case of other documents which were filed under the 1933 Act or the
         1934 Act with the Commission, an untrue statement of a material fact
         or omitted to state a material fact necessary in order to make the
         statements therein, in light of the circumstances under which they
         were made when such documents were so filed, not misleading.

                 In addition, Schiff Hardin & Waite shall include advice that
it confirms its opinion as set forth under "United States Federal Income
Taxation" in the Prospectus.

                 The foregoing opinions may be limited to the laws of New York,
Delaware and the State of Illinois and federal securities and income tax laws.
In rendering its opinion, such counsel may rely, as to matters of Delaware law
relating to the Trust, the Preferred Securities and the Declaration, upon the
opinion of Richards, Layton & Finger, P.A., special Delaware counsel to the
Company, which shall be delivered in accordance with Section 5(b)(2) hereof,
and as to matters of New York law relating to the Subordinated Debt Securities
and the Indenture, upon the opinion of Reid & Priest LLP, which shall be
delivered in accordance with Section 5(b)(4) hereof.

                                  (2)      The favorable opinion, dated as of
Closing Time, of Richards, Layton & Finger, P.A., special Delaware counsel to
the Offerors, in form and substance satisfactory to counsel for the
Underwriters, to the effect that:

                                  (i)      The Trust has been duly created and
         is validly existing in good standing as a business trust under the
         Delaware Act, and all filings required under the laws of the State of
         Delaware with respect to the creation and valid existence of the Trust
         as a business trust have been made.

                                  (ii)     Under the Delaware Act and the
         Declaration, the Trust has the power and authority to own property and
         conduct its business, all as described in the Registration Statement
         and the Prospectus.

                                  (iii)    The Declaration constitutes a valid 
         and binding obligation of the Company and the Trustees and is 
         enforceable against the Company and the Trustees in accordance with 
         its terms, subject, as





                                       22
<PAGE>   23

         to enforcement, to bankruptcy, insolvency, reorganization and other
         laws of general applicability relating to or affecting creditors'
         rights and to general equity principles.

                                  (iv)   Under the Delaware Act and the
         Declaration, the Trust has the power and authority to (i) execute and
         deliver, and to perform its obligations under, this Agreement and the
         Pricing Agreement and (ii) issue, and perform its obligations under,
         the Trust Securities.

                                  (v)    Under the Delaware Act and the
         Declaration, the execution and delivery by the Trust of this
         Agreement, the Pricing Agreement and the performance by the Trust of
         its obligations hereunder and under the Pricing Agreement, have been
         duly authorized by all necessary action on the part of the Trust.

                                  (vi)   The certificates for the Preferred
         Securities are in due and proper form; the Preferred Securities have
         been duly authorized by the Declaration and are duly and validly
         issued and, subject to qualifications hereinafter expressed in this
         paragraph (vi), fully paid and nonassessable undivided beneficial
         interests in the assets of the Trust; the holders of the Preferred
         Securities, as beneficial owners of the Trust, will 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; said counsel may note that
         the holders of the Preferred Securities may be obligated, pursuant to
         the Declaration, to (i) provide indemnity and/or security in
         connection with, and pay taxes or governmental charges arising from,
         transfers or exchanges of Preferred Securities certificates and the
         issuance of replacement Preferred Securities certificates and (ii)
         provide security and indemnity in connection with requests of or
         directions to the Property Trustee to exercise its rights and remedies
         under the Declaration.

                                  (vii)  The Common Securities have been duly
         authorized by the Declaration and are duly and validly issued and
         fully paid and, except as otherwise provided in Section 10.1(b) of the
         Declaration, nonassessable undivided beneficial interests in the
         assets of the Trust.

                                  (viii) Under the Delaware Act and the
         Declaration, the issuance of the Trust Securities is not subject to
         preemptive or other similar rights.

                                  (ix)   The issuance and sale by the Trust
         of the Trust Securities, the purchase by the Trust of the Subordinated
         Debt





                                       23
<PAGE>   24

         Securities, the execution, delivery and performance by the Trust of
         this Agreement and the Pricing Agreement, the consummation by the
         Trust of the transactions contemplated hereby and by the Pricing
         Agreement and compliance by the Trust with its obligations hereunder
         and thereunder will not violate (i) any of the provisions of the
         Certificate of Trust or the Declaration or (ii) any applicable
         Delaware law or administrative regulation.

                                  (3)      The favorable opinion, dated as of
Closing Time, of Richard, Layton & Finger, P.A., counsel of Wilmington Trust
Company, as Property Trustee under the Declaration, and Guarantee Trustee under
the Preferred Securities Guarantee Agreements, in form and substance
satisfactory to counsel for the Underwriters, to the effect that:

                                  (i)      Wilmington Trust Company is a
         Delaware banking corporation with trust powers, duly organized,
         validly existing and in good standing under the laws of the State of
         Delaware with all necessary power and authority to execute and
         deliver, and to carry out and perform its obligations under the terms
         of the Declaration and the Preferred Securities Guarantee Agreement.

                                  (ii)     The execution, delivery and
         performance by the Property Trustee of the Declaration and the
         execution, delivery and performance by the Guarantee Trustee of the
         Preferred Securities Guarantee Agreement have been duly authorized by
         all necessary corporate action on the part of the Property Trustee and
         the Guarantee Trustee, respectively.  The Declaration and the
         Preferred Securities Guarantee Agreement have been duly executed and
         delivered by the Property Trustee and the Guarantee Trustee,
         respectively, and constitute the legal, valid and binding obligations
         of the Property Trustee and the Guarantee Trustee, respectively,
         enforceable against the Property Trustee and the Guarantee Trustee,
         respectively, in accordance with their terms, subject, as to
         enforcement, to bankruptcy, insolvency, reorganization and other laws
         of general applicability relating to or affecting creditors' rights
         and to general equity principles.

                                  (iii)    The execution, delivery and 
         performance of the Declaration and the Preferred Securities Guarantee
         Agreement by the Property Trustee and the Guarantee Trustee, 
         respectively, do not conflict with or constitute a breach of the 
         Articles of Organization or Bylaws of the Property Trustee and the 
         Guarantee Trustee, respectively.

                                  (iv)     No consent, approval or authorization
         of, or registration with or notice to, any Delaware or federal banking
         authority





                                       24
<PAGE>   25

         is required for the execution, delivery or performance by the Property
         Trustee and the Guarantee Trustee of the Declaration and the Preferred
         Securities Guarantee Agreement.

                                  (4)      The favorable opinion, dated as of
Closing Time, of Reid & Priest LLP, counsel for the Underwriters, in form and
substance satisfactory to the Underwriters with respect to the incorporation
and legal existence of the Company; the formation and legal existence of the
Trust, the Preferred Securities, the Indenture, the Preferred Securities
Guarantee Agreement, this Agreement, the Pricing Agreement, the Registration
Statement, the Prospectus and other related matters as the Representative may
require.

                 In giving its opinion, Reid & Priest LLP may rely as to
certain matters of Delaware law relating to the Trust, the Preferred Securities
and the Declaration upon the opinion of Richards, Layton & Finger, P.A.,
special Delaware counsel for the Offerors, which shall be delivered in
accordance with Section 5(b)(2) hereto, and as to matters of Illinois law upon
the opinion of Schiff Hardin & Waite, counsel for the Offerors, which shall be
delivered in accordance with Section 5(b)(1) hereto.

                          (c)  At Closing Time, there shall not have been,
since the date hereof or since the respective dates as of which information is
given in the Registration Statement and the Prospectus, any material adverse
change in the condition, financial or otherwise, or in the earnings, business
affairs or business prospects of the Trust or the Company and its subsidiaries
considered as one enterprise, whether or not arising in the ordinary course of
business, and the Representative shall have received a certificate of a Vice
President of the Company and of the chief financial or chief accounting officer
of the Company and a certificate of a Regular Trustee of the Trust, and dated
as of Closing Time, to the effect that (i) there has been no such material
adverse change, (ii) the representations and warranties in Section 1 hereof are
true and correct with the same force and effect as though expressly made at and
as of Closing Time, (iii) the Trust and the Company have complied with all
agreements and satisfied all conditions on its part to be performed or
satisfied at or prior to Closing Time, and (iv) no stop order suspending the
effectiveness of the Registration Statement has been issued and no proceedings
for that purpose have been initiated or threatened by the Commission.

                          (d)  At the time of the execution of this Agreement,
the Representative shall have received from Price Waterhouse LLP a letter dated
such date, in form and substance satisfactory to the Representative, to the
effect that:





                                       25
<PAGE>   26

                                  (i)  they are independent public accountants
         with respect to the Company and its consolidated subsidiaries, within
         the meaning of the 1933 Act and the 1933 Act Regulations;

                                  (ii) in their opinion, the consolidated
         financial statements and schedules audited by them and included or
         incorporated by reference in the Registration Statement or the
         Prospectus comply as to form in all material respects with the
         accounting requirements of the 1933 Act or the Exchange Act, as
         applicable, and the related published rules and regulations
         thereunder, as applicable; they have made a review in accordance with
         standards established by the American Institute of Certified Public
         Accountants of the Company's consolidated interim financial statements
         as described in Statement on Auditing Standards ("SAS") No. 71,
         Interim Financial Information, for the periods specified in such
         letter performed at the request of the Company;

                                 (iii) based upon limited procedures set forth
         in detail in such letter, nothing has come to their attention which
         causes them to believe that:

                                        (A) the unaudited consolidated
         financial statements of the Company included in the Registration
         Statement do not comply as to form in all material respects with the
         applicable accounting requirements of the 1934 Act and the 1934 Act
         Regulations, as they apply to Form 10-Q, or are not presented in
         conformity with generally accepted accounting principles applied on a
         basis substantially consistent with that of the audited financial
         statements included in the Registration Statement,

                                        (B) the unaudited amounts of revenue
         and net income set forth under "Summary Financial Information of
         Illinois Power" in the Prospectus were not determined on a basis
         substantially consistent with that used in determining the
         corresponding amounts in the audited financial statements included in
         the Registration Statement, or

                                        (C) at a specified date not more than
         five days prior to the date of this Agreement, there has been any
         change in the capital stock of the Company and its subsidiaries or any
         increase in the consolidated long-term debt of the Company and its
         subsidiaries or any decrease in total assets or net assets as compared
         with the amounts shown on the date of the most recent consolidated
         balance sheet included in or incorporated by reference in the
         Registration Statement and the Prospectus (September 30, 1995 balance
         sheet included in the Registration Statement) or, during the period
         from the date of the most





                                       26
<PAGE>   27

         recent consolidated balance sheet included in or incorporated by
         reference in the Registration Statement and the Prospectus to a
         specified date not more than five days prior to the date of this
         Agreement, there were any decreases, as compared with the
         corresponding period in the preceding year, in operating revenues or
         net earnings available for common stock of the Company and its
         subsidiaries, except in all instances for changes, increases or
         decreases which the Registration Statement and the Prospectus disclose
         have occurred or may occur; and

                                  (iv)     in addition to the audit referred to
         in their opinions and the limited procedures referred to in clause
         (iii) above, they have carried out certain specified procedures, not
         constituting an audit, with respect to certain amounts, percentages
         and financial information which are included in the Registration
         Statement and Prospectus, or incorporated therein by reference, and
         which are specified by the Representative, and have found such
         amounts, percentages and financial information to be in agreement with
         the relevant accounting, financial and other records of the Company
         and its subsidiaries identified in such letter.

                          (e)  At Closing Time, the Representative shall have
received from Price Waterhouse LLP a letter, dated as of Closing Time, to the
effect that they reaffirm the statements made in the letter furnished pursuant
to subsection (d) of this Section, except that the specified date referred to
shall be a date not more than five days prior to Closing Time.

                          (f)  At Closing Time and each Date of Delivery, if
any, counsel for the Underwriters shall have been furnished with such documents
and opinions as they may require for the purpose of enabling them to pass upon
the issuance and sale of the Preferred Securities as herein contemplated and
related proceedings, or in order to evidence the accuracy of any of the
representations or warranties, or the fulfillment of any of the conditions,
herein contained; and all proceedings taken by the Offerors, in connection with
the issuance and sale of the Preferred Securities as herein contemplated shall
be satisfactory in form and substance to the Representative and Reid & Priest
LLP, counsel for the Underwriters.

                          (g)  At Closing Time, the Preferred Securities and
the Subordinated Debt Securities shall be rated in one of the four highest
rating categories for long term debt ("Investment Grade") by any nationally
recognized statistical rating agency, and the Trust shall have delivered to the
Representative a letter, dated the Closing Time, from such nationally
recognized statistical rating agency, or other evidence satisfactory to the
Representative, confirming that the Preferred Securities and the Subordinated
Debt Securities have Investment





                                       27
<PAGE>   28

Grade ratings; and there shall not have occurred any decrease in the ratings of
any of the debt securities of the Company or of the Preferred Securities by any
"nationally recognized statistical rating organization" (as defined for
purposes of Rule 436(g) under the 1933 Act Regulations) and such organization
shall not have publicly announced that it has under surveillance or review,
with possible negative implications, its rating of any of the debt securities
of the Company or of the Preferred Securities.

                          (h)  At the Closing Time, the Preferred Securities
shall have been approved for listing on the New York Stock Exchange upon notice
of issuance.

                 If any condition specified in this Section shall not have been
fulfilled when and as required to be fulfilled, this Agreement may be
terminated by the Representative by notice to the Offerors at any time at or
prior to Closing Time, and such termination shall be without liability of any
party to any other party except as provided in Section 4 hereof.

                 Section 6.  Indemnification

                 (a)      The Trust and the Company will jointly and severally
         indemnify and hold harmless each Underwriter against any losses,
         claims, damages or liabilities, joint or several, to which such
         Underwriter may become subject, under the 1933 Act or otherwise,
         insofar as such losses, claims, damages or liabilities (or actions in
         respect thereof) arise out of or are based upon an untrue statement or
         alleged untrue statement of a material fact contained in the
         Registration Statement, the Prospectus or any other prospectus
         relating to the Securities, or any amendment or supplement thereto, or
         arise out of or are based upon the omission or alleged omission to
         state therein a material fact required to be stated therein or
         necessary to make the statements therein, in the light of the
         circumstances under which they were made, not misleading, and will
         reimburse each Underwriter for any legal or other expenses reasonably
         incurred by such Underwriter in connection with investigating or
         defending any such action or claim as such expenses are incurred;
         provided, however, that neither the Trust nor the Company shall be
         liable in any such case to the extent that any such loss, claim,
         damage or liability arises out of or is based upon an untrue statement
         or alleged untrue statement or omission or alleged omission made in
         the Registration Statement, the Prospectus, or any other prospectus
         relating to the Securities or any such amendment or supplement in
         reliance upon and in conformity with written information furnished to
         the Trust or the Company through you expressly for use therein;





                                       28
<PAGE>   29

                 (b)      Each Underwriter will indemnify and hold harmless the
         Trust and the Company against any losses, claims, damages or
         liabilities to which the Trust or the Company may become subject,
         under the 1933 Act or otherwise, insofar as such losses, claims,
         damages or liabilities (or actions in respect thereof) arise out of or
         are based upon an untrue statement or alleged untrue statement of a
         material fact contained in the Registration Statement, the Prospectus,
         and any other prospectus relating to the Securities, or any amendment
         or supplement thereto, or arise out of or are based upon the omission
         or alleged omission to state therein a material fact required to be
         stated therein or necessary to make the statements therein not
         misleading, in each case to the extent, but only to the extent, that
         such untrue statement or alleged untrue statement or omission or
         alleged omission was made in the Registration Statement, the
         Prospectus, and any other prospectus relating to the Securities, or
         any such amendment or supplement in reliance upon and in conformity
         with written information furnished to the Trust or the Company by such
         Underwriter through you expressly for use therein; and will reimburse
         the Trust and the Company for any legal or other expenses reasonably
         incurred by the Trust or the Company in connection with investigating
         or defending any such action or claim as such expenses are incurred.

                 (c)      Promptly after receipt by an indemnified party under
         subsection (a) or (b) above of notice of the commencement of any
         action, such indemnified party shall, if a claim in respect thereof is
         to be made against the indemnifying party under such subsection,
         notify the indemnifying party in writing of the commencement thereof;
         but that the omission so to notify the indemnifying party shall not
         relieve it from any liability which it may have to any indemnifying
         party otherwise than under such subsection.  In case any such action
         shall be brought against any indemnified party and it shall notify the
         indemnifying party of the commencement thereof, the indemnifying party
         shall be entitled to participate therein and, to the extent that it
         shall wish, jointly with any other indemnifying party similarly
         notified, to assume the defense thereof, with counsel satisfactory to
         such indemnified party (who shall not, except with the consent of the
         indemnified party, be counsel to the indemnifying party), and, after
         notice from the indemnifying party to such indemnified party of its
         election so to assume the defense thereof, the indemnifying party
         shall not be liable to such indemnified party under such subsection
         for any legal expenses of other counsel or any other expenses, in each
         case subsequently incurred by such indemnified party, in connection
         with the defense thereof other than reasonable costs of investigation.
         No indemnifying party shall, without the written consent of the
         indemnified party, effect the settlement or compromise of, or consent
         to the entry of any judgment with respect to, any pending or
         threatened action or claim





                                       29
<PAGE>   30

         in respect of which indemnification or contribution may be sought
         hereunder (whether or not the indemnified party is an actual or
         potential party to such action or claim) unless such settlement,
         compromise or judgment (i) includes an unconditional release of the
         indemnified party from all liability arising out of such action or
         claim and (ii) does not include any statement as to, or an admission
         of, fault, culpability or a failure to act, by or on behalf of any
         indemnified party.  No indemnifying party shall be liable for any such
         settlement, compromise or judgment effected by the indemnified party
         without the written consent of the indemnifying party; provided,
         however, that if at any time an indemnified party shall have requested
         an indemnifying party to reimburse the indemnified party for fees and
         expenses of counsel, such indemnifying party agrees that it shall be
         liable for any such settlement, compromise or judgment effected
         without its written consent if (i) such settlement, compromise or
         judgment is entered into more than 45 days after receipt by such
         indemnifying party of the aforesaid request, (ii) such indemnifying
         party shall have received notice of the terms of such settlement,
         compromise or judgment at least 30 days prior to such settlement,
         compromise or judgment being entered into and (iii) such indemnifying
         party shall not have reimbursed such indemnified party in accordance
         with such request prior to the date of such settlement, compromise or
         judgment.

                 (d)      If the indemnification provided for in this Section 6
         is unavailable to or insufficient to hold harmless an indemnified
         party under subsection (a) or (b) above in respect of any losses,
         claims, damages or liabilities (or actions in respect thereof)
         referred to therein, then each indemnifying party shall contribute to
         the amount paid or payable by such indemnified party as a result of
         such losses, claims, damages or liabilities (or actions in respect
         thereof) in such proportion as is appropriate to reflect the relative
         benefits received by the Trust and the Company on the one hand and the
         Underwriters on the other from the offering of the Securities.  If,
         however, the allocation provided by the immediately preceding sentence
         is not permitted by applicable law or if the indemnified party failed
         to give notice required under subsection (c) above, then each
         indemnifying party shall contribute to such amount paid or payable by
         such indemnified party in such proportion as is appropriate to reflect
         not only such relative benefits but also the relative fault of the
         Trust and the Company on the one hand and the Underwriters on the
         other in connection with the statements or omissions which resulted in
         such losses, claims, damages or liabilities (or actions in respect
         thereof), as well as any other relevant equitable considerations.  The
         relative benefits received by the Trust and the Company on the one
         hand and such Underwriters on the other shall be deemed to be in the
         same





                                       30
<PAGE>   31

         proportions as the total net proceeds from the offering (before
         deducting expenses) received by the Trust and the Company bear to the
         total underwriting discounts and commissions received by such
         Underwriters.  The relative fault shall be determined by reference to,
         among other things, whether the untrue or alleged untrue statement of
         a material fact or the omission or alleged omission to state a
         material fact relates to information supplied by the Trust and the
         Company on the one hand or such Underwriters on the other and the
         parties' relative intent, knowledge, access to information and
         opportunity to correct or prevent such statement or omission.  The
         Trust, the Company and the Underwriters agree that it would not be
         just and equitable if contribution pursuant to this subsection (d)
         were determined by pro rata allocation (even if the Underwriters were
         treated as one entity for such purpose) or by any other method of
         allocation which does not take account of the equitable considerations
         referred to above in this subsection (d).  The amount paid or payable
         by an indemnified party as a result of the losses, claims, damages or
         liabilities (or actions in respect thereof) referred to above in this
         subsection (d) shall be deemed to include any legal or other expenses
         reasonably incurred by such indemnified party in connection with
         investigating or defending any such action or claim.  Notwithstanding
         the provisions of this subsection (d), no Underwriter shall be
         required to contribute any amount in excess of the amount by which the
         total price at which the Preferred Securities underwritten by it and
         distributed to the public were offered to the public exceeds the
         amount of any damages which such Underwriter has otherwise been
         required to pay by reason of such untrue or alleged untrue statement
         or omission or alleged omission.  No person guilty of fraudulent
         misrepresentation (within the meaning of Section 11(f) of the 1933
         Act) shall be entitled to contribution from any person who was not
         guilty of such fraudulent misrepresentation.  The obligations of the
         Underwriters in this subsection (d) to contribute are several in
         proportion to their respective underwriting obligations with respect
         to the Preferred Securities and not joint.

                 (e)      The obligations of the Trust and the Company under
         this Section 6 shall be in addition to any liability which the Trust
         and the Company may otherwise have and shall extend, upon the same
         terms and conditions, to each person, if any, who controls any
         Underwriter within the meaning of the 1933 Act; and the obligations of
         the Underwriters under this Section 6 shall be in addition to any
         liability which the respective Underwriters may otherwise have and
         shall extend, upon the same terms and conditions, to each officer and
         director of the Trust and the Company and to each person, if any, who
         controls the Trust or the Company within the meaning of the 1933 Act.





                                       31
<PAGE>   32

                 Section 7.  Representations, Warranties and Agreements to
Survive Delivery.  All representations, warranties and agreements contained in
this Agreement and the Pricing Agreement, or contained in certificates of
officers or Trustees of the Offerors submitted pursuant hereto, shall remain
operative and in full force and effect, regardless of any investigation made by
or on behalf of any Underwriter or controlling person, or by or on behalf of
the Offerors and shall survive delivery of the Preferred Securities to the
Underwriters.

                 Section 8.  Termination of Agreement.

                 (a)  The Representative may terminate this Agreement, by
notice to the Offerors, at any time at or prior to Closing Time (i) if there
has been, since the date of this Agreement or since the respective dates as of
which information is given in the Registration Statement, any material adverse
change in the condition financial or otherwise, or in the earnings, business
affairs or business prospects or the Trust or the Company and its subsidiaries
considered as one enterprise, whether or not arising in the ordinary course of
business, (ii) if there has occurred any material adverse change in the
financial markets in the United States or elsewhere or any outbreak of
hostilities or escalation thereof or other calamity or crisis the effect of
which is such as to make it, in the judgment of the Representative,
impracticable to market the Preferred Securities or to enforce contracts for
the sale of the Preferred Securities, (iii) if trading in the Preferred
Securities has been suspended by the Commission, or if trading generally on the
New York Stock Exchange has been suspended, limited or restricted or minimum or
maximum prices for trading have been fixed, or maximum ranges for prices for
securities have been required (excluding existing "circuit breaker" provisions
in effect under the rules of said exchange on the date hereof), by said
exchange or by order of the Commission or any other governmental authority, or
if a banking moratorium has been declared by either federal, New York, Illinois
or Delaware authorities or (iv) if there has been any decrease in the ratings
of any of the debt securities of the Company or of the Preferred Securities by
any "nationally recognized statistical rating organization" (as defined for
purposes of Rule 436(g) of the 1933 Act Regulations) or such organization shall
have publicly announced that it has under surveillance or review, with possible
negative implications, its rating of any of the debt securities of the Company
or of the Preferred Securities.

                 (b)  If this Agreement is terminated pursuant to this Section,
such termination shall be without liability of any party to any other party
except as provided in Section 4 hereof.





                                       32
<PAGE>   33

                 Section 9.  Default by One or More of the Underwriters.  If
one or more of the Underwriters shall fail at Closing Time to purchase the
Preferred Securities that it or they are obligated to purchase under this
Agreement and the Pricing Agreement (the "Defaulted Securities"), the
Representative shall have the right, within 24 hours thereafter, to make
arrangements for one or more of the non-defaulting Underwriters, or any other
underwriters, to purchase all, but not less than all, of the Defaulted
Securities in such amounts as may be agreed upon and upon the terms herein set
forth; if, however, the Representatives shall not have completed such
arrangements within such 24-hour period, then:

                 (a)      if the number of Defaulted Securities does not exceed
         10% of the Preferred Securities, each of the non-defaulting
         Underwriters shall be obligated, severally and not jointly, to
         purchase the full amount thereof in the proportions that their
         respective underwriting obligations hereunder bear to the underwriting
         obligations of all non-defaulting Underwriters, or

                 (b)      if the number of Defaulted Securities exceeds 10% of
         the Preferred Securities, this Agreement shall terminate without
         liability on the part of any non-defaulting Underwriter.

                 No action taken pursuant to this Section shall relieve any
defaulting Underwriter from liability in respect of its default.

                 In the event of any such default which does not result in a
termination of this Agreement, either the Representative or the Offerors shall
have the right to postpone Closing Time for a period not exceeding seven days
in order to effect any required changes in the Registration Statement or
Prospectus or in any other documents or arrangements.

                 Section 10.  Notices.  All notices and other communications
hereunder shall be in writing and shall be deemed to have been duly given if
mailed or transmitted by any standard form of telecommunication.  Notices to
the Underwriters shall be directed to the Representative at Merrill Lynch World
Headquarters, North Tower, World Financial Center, New York, New York
10281-1201, attention of Russell Robertson, Senior Managing Director; notices
to the Trust, and the Company shall be directed to them at 500 South 27th
Street, Decatur, Illinois 62525, attention of Daniel L. Mortland, Assistant
Treasurer.

                 Section 11.  Parties.  This Agreement and the Pricing
Agreement shall each inure to the benefit of and be binding upon the
Underwriters and the Trust, the Company and their respective successors.
Nothing expressed or mentioned in this Agreement or the Pricing Agreement is
intended or shall be





                                       33
<PAGE>   34

construed to give any person, firm or corporation, other than the Underwriters
and the Trust and the Company and their respective successors and the
controlling persons and officers, directors and trustees referred to in Section
6 and their heirs and legal representatives, any legal or equitable right,
remedy or claim under or in respect of this Agreement or the Pricing Agreement
or any provision herein or therein contained. This Agreement and the Pricing
Agreement and all conditions and provisions hereof and thereof are intended to
be for the sole and exclusive benefit of the Underwriters and the Trust and the
Company and their respective successors, and said controlling persons and
officers, directors and trustees and their heirs and legal representatives, and
for the benefit of no other person, firm or corporation.  No purchaser of
Securities from any Underwriter shall be deemed to be a successor by reason
merely of such purchase.

                 Section 12.  Governing Law and Time.  This Agreement and the
Pricing Agreement shall be governed by and construed in accordance with the
laws of the State of New York applicable to agreements made and to be performed
in said State.  Except as otherwise set forth herein, specified times of day
refer to New York City time.

                 Section 13.  Counterparts.  This Agreement may be executed by
any one or more of the parties hereto in any number of counterparts, each of
which shall be deemed to be an original, but all such respective counterparts
shall together constitute one and the same instrument.





                                       34
<PAGE>   35

                 If the foregoing is in accordance with your understanding of
our agreement, please sign and return to the Trust a counterpart hereof,
whereupon this instrument, along with all counterparts, will become a binding
agreement between the Underwriters and the Trust and the Company in accordance
with its terms.

                                        Very truly yours,
                                        
                                        ILLINOIS POWER COMPANY



                                        By
                                          ------------------------------------
                                          Title:




                                        ILLINOIS POWER FINANCING I



                                        By
                                          ------------------------------------
                                          Title:  Trustee

                                        By
                                          ------------------------------------
                                          Title:  Trustee


CONFIRMED AND ACCEPTED,
  as of the date first above written:

MERRILL LYNCH & CO.
Merrill Lynch, Pierce, Fenner & Smith
  Incorporated



By
  --------------------------
                   Authorized Signatory

For itself and as Representative of the other
Underwriters named in Schedule A hereto.
<PAGE>   36


                                   SCHEDULE A


<TABLE>
<CAPTION>
                                                                   Number
                     Name of Underwriter                       of Securities
                     -------------------                       -------------
<S>                                                            <C>
Merrill Lynch, Pierce, Fenner & Smith                   
  Incorporated  . . . . . . . . . . . . . . . . . . . . 
Bear, Stearns & Co. Inc.  . . . . . . . . . . . . . . . 
Dean Witter Reynolds Inc. . . . . . . . . . . . . . . . 
A.G. Edwards & Sons, Inc. . . . . . . . . . . . . . . . 
PaineWebber Incorporated  . . . . . . . . . . . . . . . 





Total . . . . . . . . . . . . . . . . . . . . . . . . .         4,000,000
                                                                =========
</TABLE>
<PAGE>   37

                                                                      EXHIBIT A



                     _________________ Preferred Securities

                           ILLINOIS POWER FINANCING I

                          (a Delaware business trust)

             _____% Trust Originated Preferred Securities ("TOPrS")

                    (Liquidation Amount of $25 Per Security)

                               PRICING AGREEMENT

MERRILL LYNCH & CO.                                             _________, 1995
Merrill Lynch, Pierce, Fenner
   & Smith Incorporated
         as Representative of the several
         Underwriters named in the within-
         mentioned Underwriting Agreement
Merrill Lynch World Headquarters
North Tower
World Financial Center
New York, New York 10281

Ladies and Gentlemen:

                 Reference is made to the Underwriting Agreement, dated
_________, 1995 (the "Underwriting Agreement"), relating to the purchase by the
several Underwriters named in Schedule A thereto, for whom Merrill Lynch & Co.,
Merrill Lynch, Pierce, Fenner & Smith Incorporated is acting as representative
(the "Representative"), of the above ___% Trust Originated Preferred Securities
(the "Preferred Securities"), of ILLINOIS POWER FINANCING I, a Delaware
business trust (the "Trust").

                 Pursuant to Section 2 of the Underwriting Agreement, the
Trust, Illinois Power Company (the "Company"), an Illinois corporation, agree
with each Underwriter as follows:

                          1.  The initial public offering price per security
         for the Preferred Securities, determined as provided in said Section
         2, shall be $25.00.
<PAGE>   38

                          2.  The purchase price per security for the Preferred
         Securities to be paid by the several Underwriters shall be $25.00,
         being an amount equal to the initial public offering price set forth
         above.

                          3.  The compensation per Preferred Security to be
         paid by the Company to the several Underwriters in respect of their
         commitments hereunder shall be ______; provided, however, that the
         compensation per Preferred Security for sales of 10,000 or more
         Preferred Securities to a single purchaser shall be _____.





                                       2
<PAGE>   39

                 If the foregoing is in accordance with your understanding of
our agreement, please sign and return to the Trust a counterpart hereof,
whereupon this instrument, along with all counterparts, will become a binding
agreement between the Underwriters and the Trust and the Company in accordance
with its terms.

                                        Very truly yours,

                                        ILLINOIS POWER COMPANY


                                        By
                                          ------------------------------------
                                          Title:


                                        ILLINOIS POWER FINANCING I


                                        By
                                          ------------------------------------
                                          Title:  Trustee
                                        By
                                          ------------------------------------
                                          Title:  Trustee

CONFIRMED AND ACCEPTED,
  as of the date first above written:

MERRILL LYNCH & CO.
Merrill Lynch, Pierce, Fenner & Smith
  Incorporated


By
  ----------------------------------
           Authorized Signatory

For itself and as Representative of the other
Underwriters named in the Underwriting Agreement.

<PAGE>   1
 
                                                                      EXHIBIT 12
 
                             ILLINOIS POWER COMPANY
 
         STATEMENT OF COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
                             (THOUSANDS OF DOLLARS)
   
<TABLE>
<CAPTION>
                                                                         YEAR ENDED DECEMBER 31,
                                                   --------------------------------------------------------------------
                                                        1990              1990           1991        1992        1993
                                                   --------------    --------------    --------    --------    --------
                                                                             SUPPLEMENTAL**
<S>                                                <C>               <C>               <C>         <C>         <C>
Earnings Available for Fixed Charges:
Net Income (Loss) per "Statement of Income".....      $(78,484)         $(78,484)      $109,244    $122,088    $(56,038)
  Add:
    Income Taxes:
      Current...................................        21,307            21,307         29,369      22,930      25,260
      Deferred -- Net...........................        36,545            36,545         45,990      63,739      82,057
    Allocated income taxes......................         2,608             2,608         (1,348)     (6,632)    (12,599)
    Investment tax credit -- deferred...........       (14,121)          (14,121)           (11)       (519)       (782)
    Income tax effect of disallowed costs.......       (24,759)          (24,759)            --          --     (70,638)
    Interest on long-term debt..................       191,559           191,559        176,179     160,795     154,110
    Amortization of debt expense and
      premium-net, and other interest charges...        13,162            13,162          9,004      12,195      17,007
    One-third of all rentals (Estimated to be
      representative of the interest
      component.................................         5,053             5,053          4,996       5,117       5,992
    Interest on In-Core Fuel....................         6,802             6,802          8,862       8,278       6,174
    Disallowed Clinton Plant Costs..............            --           160,328             --          --          --
                                                      --------          --------       --------    --------    --------
Earnings available for fixed charges............      $159,672          $320,000       $382,285    $387,991    $150,543
                                                      ========          ========       ========    ========    ========
Fixed charges:
  Interest on long-term debt....................      $191,559          $191,559       $176,179    $160,795    $154,110
  Amortization of debt expense and premium-net,
    and other interest charges..................        31,093            31,093         25,553      25,785      27,619
  One-third of all rentals (Estimated to be
    representative of the interest component)...         5,053             5,053          4,996       5,117       5,992
                                                      --------          --------       --------    --------    --------
Fixed charges...................................      $227,705          $227,705       $206,728    $191,697    $187,721
                                                      ========          ========       ========    ========    ========
Ratio of earnings to fixed charges..............          0.70*             1.41           1.85        2.02        0.80*
                                                      ========          ========       ========    ========    ========
 
<CAPTION>
                                                                                  12 MONTHS
                                                                                SEPTEMBER 30,
                                                       1993           1994          1995
                                                  --------------    --------    -------------
                                                                 SUPPLEMENTAL**
<S>                                                <C>              <C>         <C>
Earnings Available for Fixed Charges:
Net Income (Loss) per "Statement of Income".....     $(56,038)      $180,242      $ 205,357
  Add:
    Income Taxes:
      Current...................................       25,260         58,354         67,048
      Deferred -- Net...........................       82,057         71,177         77,773
    Allocated income taxes......................      (12,599)        (5,736)        (7,969)
    Investment tax credit -- deferred...........         (782)       (11,331)       (10,482)
    Income tax effect of disallowed costs.......      (70,638)            --             --
    Interest on long-term debt..................      154,110        135,115        133,212
    Amortization of debt expense and
      premium-net, and other interest charges...       17,007         15,826         23,682
    One-third of all rentals (Estimated to be
      representative of the interest
      component.................................        5,992          5,847          5,274
    Interest on In-Core Fuel....................        6,174          7,185          6,484
    Disallowed Clinton Plant Costs..............      270,956             --             --
                                                     --------       --------       --------
Earnings available for fixed charges............     $421,499       $456,679      $ 500,379
                                                     ========       ========       ========
Fixed charges:
  Interest on long-term debt....................     $154,110       $135,115      $ 133,212
  Amortization of debt expense and premium-net,
    and other interest charges..................       27,619         25,381         32,629
  One-third of all rentals (Estimated to be
    representative of the interest component)...        5,992          5,847          5,274
                                                     --------       --------       --------
Fixed charges...................................     $187,721       $166,343      $ 171,115
                                                     ========       ========       ========
Ratio of earnings to fixed charges..............         2.25           2.75           2.92
                                                     ========       ========       ========
</TABLE>
    
 
- -------------------------
 
 * Earnings are inadequate to cover fixed charges. Additional earnings
   (thousands) of $68,033 and $37,178 for 1990 and 1993, respectively are
   required to attain a one-to-one ratio of Earnings to Fixed Charges.
 
** Supplemental ratio of earnings to fixed charges presented to exclude
   nonrecurring item -- Disallowed Clinton Plant Costs.
<PAGE>   2
 
                             ILLINOIS POWER COMPANY
 
           STATEMENT OF COMPUTATION OF RATIO OF EARNINGS TO COMBINED
            FIXED CHARGES AND PREFERRED STOCK DIVIDEND REQUIREMENTS
                             (THOUSANDS OF DOLLARS)
   
<TABLE>
<CAPTION>
                                                                               YEAR ENDED DECEMBER 31,
                                                            --------------------------------------------------------------
                                                                1990           1990         1991        1992        1993
                                                            ------------  --------------  --------    --------    --------
                                                                          SUPPLEMENTAL**
<S>                                                         <C>             <C>           <C>        <C>          <C>
Earnings Available for Fixed Charges and Preferred Stock
  Dividend Requirements:
Net Income (Loss) per "Statement of Income"................   $(78,484)      $(78,484)    $109,244    $122,088    $(56,038)
  Add:
    Income Taxes:
      Current..............................................     21,307         21,307       29,369      22,930      25,260
      Deferred -- Net......................................     36,545         36,545       45,990      63,739      82,057
    Allocated income taxes.................................      2,608          2,608       (1,348)     (6,632)    (12,599)
    Investment tax credit -- deferred......................    (14,121)       (14,121)         (11)       (519)       (782)
    Income tax effect of disallowed costs..................    (24,759)       (24,759)          --          --     (70,638)
    Interest on long-term debt.............................    191,559        191,559      176,179     160,795     154,110
    Amortization of debt expense and premium-net, and other
      interest charges.....................................     13,162         13,162        9,004      12,195      17,007
    One-third of all rentals (Estimated to be
      representative of the interest component)............      5,053          5,053        4,996       5,117       5,992
    Interest on In-Core Fuel...............................      6,802          6,802        8,862       8,278       6,174
    Disallowed Clinton Plant Costs.........................         --        160,328           --          --          --
                                                              --------       --------     --------    --------    --------
Earnings available for fixed charges and preferred stock
  dividend requirements....................................   $159,672       $320,000     $382,285    $387,991    $150,543
                                                              ========       ========     ========    ========    ========
Fixed charges:
  Interest on long-term debt...............................   $191,559       $191,559     $176,179    $160,795    $154,110
  Amortization of debt expense and premium-net, and other
    interest charges.......................................     31,093         31,093       25,553      25,785      27,619
  One-third of all rentals (Estimated to be representative
    of the interest component).............................      5,053          5,053        4,996       5,117       5,992
  Earnings required (before taxes) for preferred stock
    dividends..............................................     36,839***      66,743       52,023      48,691      26,123***
                                                              --------       --------     --------    --------    --------
Fixed charges and preferred stock dividend requirements....   $264,544       $294,448     $258,751    $240,388    $213,844
                                                              ========       ========     ========    ========    ========
Ratio of earnings to fixed charges.........................       0.60*          1.09         1.48        1.61        0.70*
                                                              ========       ========     ========    ========    ========
 
<CAPTION>
                                                                                           12 MONTHS
                                                                                         SEPTEMBER 30,
                                                                  1993         1994          1995
                                                             --------------  --------    -------------
                                                             SUPPLEMENTAL**
<S>                                                            <C>         <C>             <C>
Earnings Available for Fixed Charges and Preferred Stock
  Dividend Requirements:
Net Income (Loss) per "Statement of Income"................     $(56,038)    $180,242      $ 205,357
  Add:
    Income Taxes:
      Current..............................................       25,260       58,354         67,048
      Deferred -- Net......................................       82,057       71,177         77,773
    Allocated income taxes.................................      (12,599)      (5,736)        (7,969)
    Investment tax credit -- deferred......................         (782)     (11,331)       (10,482)
    Income tax effect of disallowed costs..................      (70,638)          --             --
    Interest on long-term debt.............................      154,110      135,115        133,212
    Amortization of debt expense and premium-net, and other
      interest charges.....................................       17,007       15,826         23,682
    One-third of all rentals (Estimated to be
      representative of the interest component)............        5,992        5,847          5,274
    Interest on In-Core Fuel...............................        6,174        7,185          6,484
    Disallowed Clinton Plant Costs.........................      270,956           --             --
                                                                --------     --------       --------
Earnings available for fixed charges and preferred stock
  dividend requirements....................................     $421,499     $456,679      $ 500,379
                                                                ========     ========       ========
Fixed charges:
  Interest on long-term debt...............................     $154,110     $135,115      $ 133,212
  Amortization of debt expense and premium-net, and other
    interest charges.......................................       27,619       25,381         32,629
  One-third of all rentals (Estimated to be representative
    of the interest component).............................        5,992        5,847          5,274
  Earnings required (before taxes) for preferred stock
    dividends..............................................       43,100       39,947         37,019
                                                                --------     --------       --------
Fixed charges and preferred stock dividend requirements....     $230,821     $206,290      $ 208,134
                                                                ========     ========       ========
Ratio of earnings to fixed charges.........................         1.83         2.21           2.40
                                                                ========     ========       ========
</TABLE>
    
 
- -------------------------
 
  * Earnings are inadequate to cover fixed charges. Additional earnings
    (thousands) of $68,033 and $37,178 for 1990 and 1993, respectively, are
    required to attain a one-to-one ratio of Earnings to Fixed Charges.
 
 ** Supplemental ratio of earnings to fixed charges presented to exclude
    nonrecurring item -- Disallowed Clinton Plant Costs.
 
*** Because the Company incurred a pre-tax loss, these amounts are at the net
    preferred dividend requirement level.

<PAGE>   1
 
                                                                   EXHIBIT 23(C)
 
                       CONSENT OF INDEPENDENT ACCOUNTANTS
 
     We hereby consent to the incorporation by reference in the Prospectus
constituting part of this Registration Statement on Form S-3 of our report dated
February 1, 1995, which appears on page A-10 of the 1994 Annual Report to
Shareholders of Illinois Power Company in the appendix to the Illinois Power
Company Information Statement, which is incorporated by reference in Illinois
Power Company's Annual Report on Form 10-K for the year ended December 31, 1994.
We also consent to the reference to us under the heading "Experts" in such
Prospectus.
 
PRICE WATERHOUSE LLP
   
St. Louis, Missouri
    
   
November 21, 1995
    


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