NBT BANCORP INC
8-K, 2000-04-28
NATIONAL COMMERCIAL BANKS
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                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

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

                                    FORM 8-K

                                 CURRENT REPORT
                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


Date  of  Report   (Date  of   earliest   event   reported)   April   19,   2000
                                                             -------------------

                                NBT Bancorp Inc.
      --------------------------------------------------------------------
                  (Exact Name of Registrant as Specified in Charter)

         Delaware                       0-14703               16-1268674
- -------------------------------------------------------------------------------
   (State or Other Jurisdiction      (Commission            (IRS Employer
         of Incorporation)           File Number)        Identification Number)

   52 South Broad Street, Norwich, New York                13815
- -------------------------------------------------------------------------------
(Address of Principal Executive Office)                 (Zip Code)

Registrant's telephone number, including area code        607/337-2265
                                                   -------------------

                                       N/A
- -------------------------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)

<PAGE>

Item 5. Other Events.

         On April 20, 2000,  NBT Bancorp Inc., a Delaware  corporation  ("NBT"),
and BSB Bancorp,  Inc., a Delaware corporation ("BSB"),  announced that they had
entered  into an Agreement  and Plan of Merger,  dated as of April 19, 2000 (the
"Merger Agreement").

         Pursuant  to  the  Merger  Agreement,  BSB  and  NBT  will  merge  (the
"Merger"), with NBT being the surviving corporation, to create a holding company
with  assets  of $4.7  billion.  A new name  will be  chosen  for the  surviving
corporation  before the Merger  occurs.  Stockholders  of BSB will  receive  two
shares of NBT  common  stock for each  share  exchanged.  Based on the April 19,
2000,  closing  price of NBT common  stock on the Nasdaq  National  Market,  the
transaction  is valued at $251  million or $24.00 per share for the  outstanding
common  stock of BSB.  The Merger,  which has been  unanimously  approved by the
boards of directors of NBT and BSB, is subject to the approval of each company's
stockholders and of banking  regulators.  The Merger is expected to close in the
fourth   quarter  of  2000  and  is   intended   to  be   accounted   for  as  a
pooling-of-interests and to qualify as a tax-free exchange for BSB stockholders.

         BSB has  provided  NBT an option to acquire a number of shares of BSB's
common stock equal to 19.9% of BSB's common  stock  outstanding  as of the first
date the option becomes  exercisable;  the option is exercisable in the event of
certain circumstances  involving  transactions with third parties, acts of third
parties, or break-up of the Merger Agreement.  NBT has provided BSB an option to
acquire a number of shares of NBT's  common stock equal to 19.9% of NBT's common
stock  outstanding  as of the first date the  option  becomes  exercisable;  the
option  is  exercisable  in  the  event  of  certain   circumstances   involving
transactions  with third  parties,  acts of third  parties,  or  break-up of the
Merger Agreement.

         The combined  company will have a 15-seat board of directors which will
be made up of seven  directors  from  BSB and six  from NBT plus one from  NBT's
newly acquired Lake Ariel  Bancorp,  Inc.  Pennsylvania  subsidiary and one from
Pioneer  American  Holding Company Corp.  ("Pioneer  American"),  subject to the
closing of the merger of NBT and Pioneer American. If the merger between NBT and
Pioneer American is not consummated before the effective time of the Merger, the
board of directors of the combined company will consist of 13 directors,  six of
whom will be designated  by the BSB board of directors,  six by the NBT board of
directors,  and one  former  Lake Ariel  board  member who is serving on the NBT
board at the effective  time of the Merger.  This former Lake Ariel board member
will be  designated  by the NBT  board.  Common  stockholders  of NBT will  have
ownership of approximately 53 percent of the combined company while BSB's common
stockholders will own approximately 47 percent,  assuming  consummation of NBT's
previously announced agreement to merge with Pioneer American.

<PAGE>

         Immediately  following the Merger,  NBT's and BSB's  principal  banking
subsidiaries,  NBT Bank, N.A. and BSB Bank & Trust Company, will merge, with NBT
Bank being the resulting  bank in the bank merger,  to create one of the largest
independent  community  banks in  upstate  New York.  The new bank will serve 12
counties  from more than 55 offices and over 100 ATMs. A new name will be chosen
for the resulting bank prior to the Merger. The combined company will have three
direct  operating  subsidiaries  including two  community  banks and a financial
services company.

         Daryl R. Forsythe,  president and chief executive  officer of NBT, will
become the  chairman,  president  and chief  executive  officer of the  combined
company and William C. Craine, chairman of BSB, will become the vice chairman of
the  combined  company  and  chairman  of the  executive  committee.  NBT Bank's
president  and chief  operating  officer,  Martin A.  Dietrich,  will become the
president and chief operating officer of the company's New York bank. Michael J.
Chewens, executive vice president and chief financial officer of NBT, will serve
as chief  financial  officer  for the  combined  company.  Other  members of the
executive management teams at NBT and BSB will retain key roles including: Glenn
R. Small and John R.  Bradley,  executive  vice  presidents of lending and Larry
Denniston, senior vice president and corporate secretary.

         The  corporate  offices  of the  combined  company  will be  located in
Binghamton.  Other major bank  functions  will be conducted  from the  company's
Norwich, Binghamton and Scranton locations following the Merger.

Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits.


                  (a) Not Applicable.

                  (b) Not Applicable.

                  (c) Exhibits.


         The  following   exhibits  are  filed  with  this  Current   Report  or
incorporated by reference into this Current Report on Form 8-K:


Exhibit
Number            Description
- ------            -----------

2.1               Agreement and Plan of  Merger, dated as of April 19, 2000, by
                  and between NBT Bancorp Inc. and BSB Bancorp, Inc.


<PAGE>


2.2               Form of Plan of Merger  between  BSB Bank & Trust  Company and
                  NBT Bank, National  Association,  is part of the Agreement and
                  Plan of Merger, which is filed as Exhibit 2.1 above.

2.3               The BSB Stockholder Agreement,  dated as of April 19, 2000, is
                  part of the  Agreement  and Plan of Merger,  which is filed as
                  Exhibit 2.1 above.

2.4               The NBT Stockholder Agreement,  dated as of April 19, 2000, is
                  part of the  Agreement  and Plan of Merger,  which is filed as
                  Exhibit 2.1 above.

2.5               BSB Stock  Option  Agreement,  dated  April 19,  2000,  by and
                  between BSB Bancorp,  Inc. as "Issuer" and NBT Bancorp Inc. as
                  "Grantee" is part of the Agreement  and Plan of Merger,  which
                  is filed as Exhibit 2.1 above.

2.6               NBT Stock  Option  Agreement,  dated  April 19,  2000,  by and
                  between NBT Bancorp Inc. as "Issuer" and BSB Bancorp,  Inc. as
                  "Grantee" is part of the Agreement  and Plan of Merger,  which
                  is filed as Exhibit 2.1 above.

99.1              Press release, dated April 20, 2000.


<PAGE>


                                    SIGNATURE

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                           NBT BANCORP INC.


                                           By:  /s/ Daryl R. Forsythe
                                                ---------------------
                                                Name: Daryl R. Forsythe
                                                Title: President and Chief
                                                Executive Officer

Date:  April 27, 2000



<PAGE>

                                  EXHIBIT INDEX
                                  -------------

2.1               Agreement  and Plan of Merger,  dated as of April 19, 2000, by
                  and between NBT Bancorp Inc. and BSB Bancorp, Inc.

2.2               Form of Plan of Merger  between  BSB Bank & Trust  Company and
                  NBT Bank, National  Association,  is part of the Agreement and
                  Plan of Merger, which is filed as Exhibit 2.1 above.

2.3               The BSB Stockholder Agreement,  dated as of April 19, 2000, is
                  part of the  Agreement  and Plan of Merger,  which is filed as
                  Exhibit 2.1 above.

2.4               The NBT Stockholder Agreement,  dated as of April 19, 2000, is
                  part of the  Agreement  and Plan of Merger,  which is filed as
                  Exhibit 2.1 above.

2.5               BSB Stock  Option  Agreement,  dated  April 19,  2000,  by and
                  between BSB Bancorp,  Inc. as "Issuer" and NBT Bancorp Inc. as
                  "Grantee" is part of the Agreement  and Plan of Merger,  which
                  is filed as Exhibit 2.1 above.

2.6               NBT Stock  Option  Agreement,  dated  April 19,  2000,  by and
                  between NBT Bancorp Inc. as "Issuer" and BSB Bancorp,  Inc. as
                  "Grantee" is part of the Agreement  and Plan of Merger,  which
                  is filed as Exhibit 2.1 above.

99.1              Press release, dated April 20, 2000.


                                                                     EXHIBIT 2.1

                          AGREEMENT AND PLAN OF MERGER

                                 BY AND BETWEEN

                                NBT BANCORP INC.

                                       AND

                                BSB BANCORP, INC.

                           DATED AS OF APRIL 19, 2000


<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>

                                                                                                                 Page
                                                                                                                 ----

<S>                                                                                                              <C>
ARTICLE I  THE MERGER.............................................................................................2

      SECTION 1.01.  The Merger...................................................................................2
      SECTION 1.02.  Effective Time...............................................................................2
      SECTION 1.03.  Effect of the Merger.........................................................................3
      SECTION 1.04.  Certificate of Incorporation and Bylaws......................................................3
      SECTION 1.05.  Senior Executive Officers....................................................................3
      SECTION 1.06.  Representation on the Board of the Surviving Corporation.....................................4
      SECTION 1.07   Composition of the Board of the Resulting Bank...............................................5
      SECTION 1.08.  Conversion of Common Stock...................................................................5
      SECTION 1.09.  Exchange of Certificates.....................................................................6
      SECTION 1.10.  Treatment of Stock Options...................................................................8
      SECTION 1.11.  Stock Transfer Books.........................................................................9
      SECTION 1.12.  Anti-Dilution Adjustment....................................................................10
      SECTION 1.13.  Tax Consequences............................................................................10

ARTICLE II  REPRESENTATIONS AND WARRANTIES OF BSB................................................................10

      SECTION 2.01.  Organization and Qualification of BSB; Subsidiaries.........................................11
      SECTION 2.02.  Certificate of Incorporation and Bylaws.....................................................12
      SECTION 2.03.  Capitalization..............................................................................12
      SECTION 2.04.  Authority; State Takeover Laws; Certificate of Incorporation................................13
      SECTION 2.05.  No Conflict; Required Filings and Consents..................................................13
      SECTION 2.06.  Compliance..................................................................................15
      SECTION 2.07.  Securities and Banking Reports; Financial Statements........................................15
      SECTION 2.08.  Absence of Certain Changes or Events........................................................16
      SECTION 2.09.  Absence of Litigation and Agreements........................................................16
      SECTION 2.10.  Employee Benefit Plans......................................................................17
      SECTION 2.11.  Material Contracts..........................................................................20
      SECTION 2.12.  Environmental Matters.......................................................................20
      SECTION 2.13.  Taxes.......................................................................................21
      SECTION 2.14.  Affiliates..................................................................................23
      SECTION 2.15.  Derivative Instruments......................................................................23
      SECTION 2.16.  Regulatory Approvals........................................................................23
      SECTION 2.17.  Brokers.....................................................................................23
      SECTION 2.18.  Pooling of Interests and Tax Matters........................................................24
      SECTION 2.19.  Vote Required...............................................................................24
      SECTION 2.20.  Fairness Opinion............................................................................24
      SECTION 2.21.  Rights Agreement............................................................................24

<PAGE>

ARTICLE III  REPRESENTATIONS AND WARRANTIES OF NBT...............................................................24

      SECTION 3.01.  Organization and Qualification of NBT; Subsidiaries.........................................24
      SECTION 3.02.  Certificate of Incorporation and Bylaws.....................................................26
      SECTION 3.03.  Capitalization..............................................................................26
      SECTION 3.04.  Authority...................................................................................27
      SECTION 3.05.  No Conflict; Required Filings and Consents..................................................27
      SECTION 3.06.  Compliance..................................................................................29
      SECTION 3.07.  Securities and Banking Reports; Financial Statements........................................29
      SECTION 3.08.  Absence of Certain Changes or Events........................................................30
      SECTION 3.09.  Absence of Litigation and Agreements........................................................30
      SECTION 3.10.  Employee Benefit Plans......................................................................31
      SECTION 3.11.  Material Contracts..........................................................................33
      SECTION 3.12.  Environmental Matters.......................................................................34
      SECTION 3.13.  Taxes.......................................................................................35
      SECTION 3.14.  Affiliates..................................................................................35
      SECTION 3.15.  Derivative Instruments......................................................................36
      SECTION 3.16.  Regulatory Approvals........................................................................36
      SECTION 3.17.  Brokers.....................................................................................36
      SECTION 3.18.  Pooling of Interest and Tax Matters.........................................................36
      SECTION 3.19.  Votes Required..............................................................................37
      SECTION 3.20.  Fairness Opinion............................................................................37
      SECTION 3.21   Rights Agreement............................................................................37

ARTICLE IV  COVENANTS OF BSB AND NBT.............................................................................37

      SECTION 4.01.  Affirmative Covenants.......................................................................37
      SECTION 4.02.  Negative Covenants..........................................................................38

ARTICLE V  ADDITIONAL AGREEMENTS.................................................................................40

      SECTION 5.01.  Registration Statement; Joint Proxy Statement...............................................40
      SECTION 5.02.  Meetings of Shareholders....................................................................42
      SECTION 5.03.  Access to Information; Confidentiality......................................................43
      SECTION 5.04.  Appropriate Action; Consents; Filings.......................................................43
      SECTION 5.05.  No Solicitation of Transactions.............................................................44
      SECTION 5.06.  Indemnification.............................................................................46
      SECTION 5.07.  Employee Benefits...........................................................................47
      SECTION 5.08.  Executive Agreements and Employee Severance.................................................49
      SECTION 5.09.  Notification of Certain Matters.............................................................49
      SECTION 5.10.  Public Announcements........................................................................49
      SECTION 5.11.  Expenses....................................................................................49
      SECTION 5.12.  Delivery of Stockolder List.................................................................50
      SECTION 5.13.  Letters of Accountants......................................................................50
      SECTION 5.14.  BSB Reports.................................................................................51

</TABLE>

<PAGE>

<TABLE>
<CAPTION>

<S>                                                                                                              <C>
      SECTION 5.15.  NBT Reports.................................................................................51
      SECTION 5.16.  Pooling.....................................................................................52
      SECTION 5.17.  Disclosure Schedules........................................................................52
      SECTION 5.18.  Regulatory Matters..........................................................................52

ARTICLE VI  CONDITIONS OF MERGER.................................................................................53

      SECTION 6.01.  Conditions to Obligation of Each Party to Effect the Merger.................................53
      SECTION 6.02.  Additional Conditions to Obligations of NBT.................................................54
      SECTION 6.03.  Additional Conditions to Obligations of BSB.................................................55

ARTICLE VII  TERMINATION, AMENDMENT AND WAIVER...................................................................56

      SECTION 7.01.  Termination.................................................................................56
      SECTION 7.02.  Effect of Termination.......................................................................57
      SECTION 7.03.  Amendment...................................................................................57
      SECTION 7.04.  Waiver......................................................................................58

ARTICLE VIII  GENERAL PROVISIONS.................................................................................58

      SECTION 8.01.  Closing.....................................................................................58
      SECTION 8.02.  Non-Survival of Representations, Warranties and
                     Agreements..................................................................................58
      SECTION 8.03.  Notices.....................................................................................58
      SECTION 8.04.  Additional Definitions......................................................................59
      SECTION 8.05.  Headings....................................................................................60
      SECTION 8.06.  Severability................................................................................60
      SECTION 8.07.  Entire Agreement............................................................................60
      SECTION 8.08.  Assignment..................................................................................61
      SECTION 8.09.  Parties in Interest.........................................................................61
      SECTION 8.10.  Governing Law...............................................................................61
      SECTION 8.11.  Counterparts................................................................................61

EXHIBITS

A                 BANK PLAN OF MERGER
B                 BSB STOCK OPTION AGREEMENT
C                 NBT STOCK OPTION AGREEMENT
D                 CERTIFICATE OF MERGER
E                 SENIOR EXECUTIVE OFFICERS
F                 BSB STOCKHOLDER AGREEMENT
G                 NBT STOCKHOLDER AGREEMENT

</TABLE>


<PAGE>

                          AGREEMENT AND PLAN OF MERGER

                  AGREEMENT AND PLAN OF MERGER, dated as of April 19, 2000 (this
"Agreement"),  by and between NBT BANCORP INC, a Delaware  corporation  ("NBT"),
and BSB  BANCORP,  INC, a Delaware  corporation  ("BSB") (at times,  referred to
herein as the "Party" or the "Parties").

                              W I T N E S S E T H:

                  WHEREAS,  NBT is a registered  bank  holding  company with the
Board of Governors of the Federal  Reserve System ("FRB") under the Bank Holding
Company Act of 1956, as amended (the "BHCA"); and

                  WHEREAS, BSB is a registered bank holding company with the FRB
under the BHCA; and

                  WHEREAS,   the  Boards  of  Directors  of  NBT  and  BSB  have
determined  it is  advisable  and in the  best  interests  of  their  respective
companies and  stockholders to consummate the business  combination  transaction
provided for herein in which BSB will,  subject to the terms and  conditions set
forth herein, merge with and into NBT, with NBT being the Surviving  Corporation
(as hereinafter defined) (the "Merger"); and

                  WHEREAS, prior to consummation of the Merger, NBT and BSB will
cause BSB Bank & Trust Company, a New  York-chartered  commercial bank and trust
company headquartered in Binghamton, New York and wholly owned subsidiary of BSB
("BSB Bank"), and NBT Bank, National Association, a national banking association
headquartered  in Norwich,  New York and wholly  owned  subsidiary  of NBT ("NBT
Bank"),  to enter into a bank plan of  merger,  in the form  attached  hereto as
Exhibit A (the "Bank Merger  Agreement"),  providing  for the merger of BSB Bank
with and into NBT Bank (the "Bank  Merger"),  with NBT Bank being the  resulting
bank of the Bank Merger (the "Resulting Bank"), and it is intended that the Bank
Merger be consummated immediately after consummation of the Merger; and

                  WHEREAS,  in order to effect the  aforementioned  combination,
the  respective  Boards  of  Directors  of NBT and BSB  have (i)  determined  in
accordance with the General  Corporation Law of the State of Delaware ("Delaware
Law") that the Merger,  pursuant and subject to the terms and conditions of this
Agreement,   is  advisable  and  in  the  best  interests  of  their  respective
corporations  and their  stockholders,  and (ii) adopted a resolution  approving
this Agreement and the other transactions contemplated hereby; and

<PAGE>

                  WHEREAS,  the  Board  of  Directors  of NBT  has  resolved  to
recommend  approval of this Agreement and the Merger by the stockholders of NBT;
and

                  WHEREAS,  the  Board  of  Directors  of BSB  has  resolved  to
recommend  approval of this Agreement and the Merger by the stockholders of BSB;
and

                  WHEREAS,  NBT and BSB intend to effect a merger that qualifies
for  pooling  of  interests   accounting  treatment  and  that  qualifies  as  a
reorganization  under  Section  368(a) of the Internal  Revenue Code of 1986, as
amended (the "Code") with this Agreement representing the plan of reorganization
for purposes of the Code; and

                  WHEREAS,  as a condition  and  inducement to NBT to enter into
this  Agreement,  BSB  will  enter  into a stock  option  agreement  in the form
attached hereto as Exhibit B (the "BSB Stock Option Agreement"); and

                  WHEREAS,  as a condition  and  inducement to BSB to enter into
this  Agreement,  NBT  will  enter  into a stock  option  agreement  in the form
attached hereto as Exhibit C (the "NBT Stock Option Agreement"); and

                  WHEREAS the Parties  desire to make  certain  representations,
warranties  and  agreements in connection  with the Merger and also to prescribe
certain conditions to the Merger;

                  NOW,  THEREFORE,  in  consideration  of the  foregoing and the
mutual covenants and agreements  herein  contained,  and intending to be legally
bound hereby, the Parties hereby agree as follows:

                                    ARTICLE I

                                   THE MERGER

                  SECTION 1.01.  The Merger.

                  Subject  to the terms and  conditions  of this  Agreement,  in
accordance with Delaware Law, at the Effective Time (as defined in Section 1.02)
BSB shall  merge  with and into NBT.  As a result of the  Merger,  the  separate
corporate  existence of BSB shall cease and NBT will  continue as the  surviving
corporation of the Merger (the "Surviving Corporation").

                  SECTION 1.02.  Effective Time.

                  The Merger shall become  effective on the date and at the time
specified  in the  Certificate  of  Merger  (the  "Certificate  of  Merger")  in
substantially the form attached as Exhibit D hereto, as filed with the Secretary
of State of the  State  of  Delaware  (the  date  and time so  specified  in the
Certificate of Merger is hereinafter referred to as the "Effective Time").

                                       2

<PAGE>


                  SECTION 1.03.  Effect of the Merger.

                        (a) Legal Effect.  At and after the Effective  Time, the
Merger shall have the effects set forth in Sections 259 and 261 of Delaware Law.

                        (b) Name Changes. The names of the Surviving Corporation
and the Resulting Bank shall be changed at the Effective Time to new names to be
determined by mutual agreement of the Parties within 45 days after the execution
of this Agreement;  provided that neither the Surviving  Corporation's  new name
nor the Resulting Bank's new name shall include "NBT" or "BSB."

                        (c) Post-Merger Operations. Upon the Merger, the Parties
intend that the headquarters and principal offices of the Surviving  Corporation
will be in Binghamton,  New York. It is further  anticipated  that the Surviving
Corporation  and its  subsidiaries  will, for the foreseeable  future,  maintain
significant  operations  in  Chenango  and  Oneida  Counties,  New  York  and in
Lackawanna County, Pennsylvania.

                  SECTION 1.04.  Certificate of Incorporation and Bylaws.

                        (a)  At  the  Effective   Time,   the   Certificate   of
Incorporation,  as amended,  of NBT in effect immediately prior to the Effective
Time shall be amended in the Merger by (i)  amending  Article  FIRST  thereof to
reflect the new name of the Surviving  Corporation and by (ii) amending  Article
FOURTH thereof to read as follows:

                 "FOURTH:  The total  number of shares of all  classes  of stock
                  which the Corporation shall have the authority to issue is One
                  Hundred Five Million (105,000,000)  shares,  consisting of One
                  Hundred Million  (100,000,000) shares of Common Stock having a
                  par  value of $.01 per  share  and  Five  Million  (5,000,000)
                  shares  of  Preferred  Stock  having  a par  value of $.01 per
                  share."

As so amended,  the Certificate of Incorporation of NBT shall be the Certificate
of Incorporation of the Surviving Corporation. At the Effective Time, the Bylaws
of NBT in effect immediately prior to the Effective Time shall become the Bylaws
of the Surviving Corporation, except that the Bylaws shall be revised to reflect
the new name of the Surviving Corporation.

                        (b)  At  the  Effective   Time,   the   Certificate   of
Organization,  Articles  of  Association  and  Bylaws  of  NBT  Bank  in  effect
immediately  prior  to the  Effective  Time  shall  become  the  Certificate  of
Organization,  Articles of Association and Bylaws of the Resulting Bank,  except
that such  organizational  documents shall be amended to reflect the new name of
the Resulting Bank.

                  SECTION 1.05.  Senior Executive Officers..

                  At the  Effective  Time,  the  persons  listed  in  Exhibit  E
attached  hereto shall serve as the senior  executive  officers of the Surviving
Corporation  and the senior  executive  officers  of the  Resulting  Bank in the
capacities noted opposite their respective names.

                                       3

<PAGE>

                  SECTION 1.06.  Representation  on  the  Board of the Surviving
                                 Corporation

                        (a) (i) If the proposed  acquisition of Pioneer American
Holding Company Corp.  ("Pioneer") by NBT is consummated  prior to the Effective
Time, at the Effective Time, the board of directors of the Surviving Corporation
shall consist of 15 directors,  seven of whom shall be designated by BSB's board
of  directors  and six of whom shall be  designated  by NBT's board of directors
from among the  existing  membership  of their  respective  boards of  directors
immediately prior to the Effective Time. In designating these directors, each of
BSB and NBT shall  allocate  those  directors to Class 1, Class 2 and Class 3 as
equally as possible. In addition,  NBT shall designate one director,  from among
the former  members of the board of directors of Lake Ariel  Bancorp,  Inc. (the
"Former  Lake  Members")  who are  serving on the board of NBT at the  Effective
Time.  If there are no such Former Lake  Members,  NBT shall  designate  another
Former Lake Member.  NBT shall also designate one director from among the former
members of the board of directors of Pioneer (the "Former Pioneer  Members") who
are  serving  on the Board of NBT at the  Effective  Time.  If there are no such
Former Pioneer Members at the Effective Time, NBT shall designate another Former
Pioneer  Member.  The  Former  Lake  Member  and the  Former  Pioneer  Member so
designated  shall become  directors of the  Surviving  Corporation  and shall be
allocated to the classes on the board of directors as equally as possible.  (ii)
If the proposed acquisition of Pioneer is not consummated prior to the Effective
Time,  the board of directors of the Surviving  Corporation  shall consist of 13
directors,  six of whom shall be designated by BSB's board of directors,  six of
whom shall be  designated by NBT's board of directors and one Former Lake Member
designated by NBT who is serving on the Board of NBT at the  Effective  Time. If
there are no such Former Lake Members,  NBT shall designate  another Former Lake
Member.  The  directors  designated by each of BSB and NBT shall be allocated to
classes as equally as possible. (iii) The selections to be made pursuant to this
Section  1.06(a) shall be made no later than 20 Business Days following the date
of this  Agreement and shall be noted on Schedule  1.06(a) to be attached to and
deemed  a part  of this  Agreement.  It is  agreed  that  if any  individual  so
designated  shall be unable or unwilling to serve as a director of the Surviving
Corporation at the Effective  Time, the party that  designated  such  individual
shall designate another individual,  who was eligible under this Section 1.06(a)
to have been so designated  on or before 20 Business Days  following the date of
this Agreement,  to serve in such individual's  place. If no other individual is
so  eligible,  then  the  size  of the  board  of  directors  of  the  Surviving
Corporation  shall be reduced by one. BSB and NBT agree to  establish  within 20
Business Days following the date of this Agreement  transition  committees to be
comprised of the  individuals  designated  to serve on the Board of Directors of
the  Surviving  Corporation   ("Transition   Committees")  and  such  Transition
Committees shall meet periodically at times to be decided by mutual agreement of
BSB and NBT until the Effective Date.

                        (b) It is agreed  that the  composition  of the board of
directors of the Surviving Corporation outlined in paragraph (a) of this Section
1.06  implements  an interim  program that will change over time as the board of
directors of the Surviving  Corporation  is expanded to include  persons who are
not  currently  directors of NBT,  BSB, or Pioneer and whose  membership  on the
board of directors of the Surviving  Corporation will afford  representation  to
communities  within the present and  prospective  service area of the  Surviving
Corporation which are not currently represented on the board of directors of the
Surviving Corporation.

                                       4

<PAGE>

                        (c) The initial  chairmanships  of the committees of the
Board  of  Directors  of the  Surviving  Corporation  shall  be as set  forth in
Schedule 1.06(c), to be attached and deemed a part of this Agreement.

                  SECTION 1.07   Composition of the Board of the Resulting Bank

                  At the Effective Time, the board of directors of the Resulting
Bank shall  consist of the chairman of the board of  directors of the  Surviving
Corporation, who shall serve as the chairman of the board of the Resulting Bank,
and eight,  ten or twelve other persons,  half of whom will be designated by NBT
and half of whom will be  designated  by BSB.  The number of such other  persons
shall be agreed upon by NBT and BSB, and in the absence of timely agreement such
number  shall be set at ten.  The  number  of  directors  and the  selection  of
directors  to be  designated  by NBT and  BSB  under  this  paragraph  shall  be
determined  and made no later than 20 Business  Days  following the date of this
Agreement  and shall be noted on  Schedule  1.07 to be  attached to and deemed a
part of this Agreement, provided, that the president of the Resulting Bank shall
be one of the directors so designated by NBT.

                  SECTION 1.08.  Conversion of Common Stock.

                  At the Effective Time, by virtue of the Merger and without any
action  on the  part  of  NBT,  BSB,  or  the  holders  of any of the  following
securities:

                        (a) Each share of BSB common  stock,  par value $.01 per
share  ("BSB  Common  Stock")  (all  such  shares  of  BSB  Common  Stock  being
hereinafter  collectively  referred to as the "Shares")  issued and  outstanding
immediately  prior to the Effective  Time (other than any Shares to be cancelled
pursuant to Section  1.8(b)) shall,  by virtue of this Agreement and without any
action on the part of the holder  thereof,  be  converted,  in  accordance  with
Section  1.09,  into the right to receive  two  shares,  as may be  adjusted  as
provided  elsewhere  herein, of NBT common stock, par value $.01 per share ("NBT
Common Stock") (the "Exchange Ratio"). As of the Effective Time, all such Shares
shall no longer be outstanding and shall  automatically be cancelled and retired
and shall cease to exist, and each certificate previously  representing any such
Shares  shall   thereafter   represent   the  right  to  receive  a  certificate
representing  shares of NBT Common Stock into which such Shares are convertible.
For the  purposes of this  Agreement,  references  to BSB Common  Stock shall be
deemed to include, where appropriate,  references to the right to receive shares
of BSB Series A Junior  Participating  Preferred  Stock  pursuant  to the Rights
Agreement,  dated as of May 24, 1999, as amended  between BSB and American Stock
Transfer & Trust  Company  ("AST")  (the "BSB Rights  Agreement").  Certificates
previously representing Shares shall be exchanged for certificates  representing
whole  shares of NBT Common  Stock  issued in  consideration  therefor  upon the
surrender of such  certificates  in  accordance  with the  provisions of Section
1.09,  without  interest.  No  fractional  shares of NBT Common  Stock  shall be
issued,  and, in lieu thereof,  a cash payment shall be made pursuant to Section
1.09 hereof.

                        (b)  Each  Share  held in the  treasury  of BSB and each
Share  owned by NBT or any direct or indirect  wholly  owned  subsidiary  of NBT
immediately  prior to the  Effective  Time (other than Shares held,  directly or
indirectly,  by NBT,  any NBT  Subsidiary,  BSB or any BSB  Subsidiary  in trust
accounts,  managed  accounts  and the like

                                       5

<PAGE>

or otherwise  held in a fiduciary or custodial  capacity  that are  beneficially
owned by third  parties and Shares held by NBT, any NBT  Subsidiary,  BSB or any
BSB Subsidiary in respect of debt previously  contracted) shall be cancelled and
extinguished  without any  conversion  thereof and no payment shall be made with
respect thereto.

                  SECTION 1.09.  Exchange of Certificates.

                         (a) Exchange Agent. As of the Effective Time, NBT shall
deposit,  or shall cause to be deposited,  with American  Stock Transfer & Trust
Company (the "Exchange Agent"), solely for the benefit of the holders of Shares,
for  exchange in  accordance  with this  Article I through the  Exchange  Agent,
certificates  representing the shares of NBT Common Stock (such certificates for
shares of NBT  Common  Stock,  and cash in lieu of  fractional  shares (if any),
together  with any  dividends  or  distributions  with  respect  thereto,  being
hereinafter  referred to as the "Exchange  Fund",  issuable  pursuant to Section
1.08 in exchange for outstanding Shares.

                         (b) Exchange Procedures. Within two Business Days after
the  Effective  Time,  NBT shall cause the Exchange  Agent to mail or personally
deliver  to  each  holder  of  record  (or  his  or her  attorney-in-fact)  of a
certificate  or  certificates  which  immediately  prior to the  Effective  Time
represented outstanding Shares (the "Certificates"), whose Shares were converted
into the right to receive  shares of NBT Common  Stock  pursuant to Section 1.08
and cash in lieu of fractional shares of NBT Common Stock (if any), (i) a letter
of transmittal (which shall specify that delivery shall be effected, and risk of
loss and  title to the  Certificates  shall  pass,  only  upon  delivery  of the
Certificates to the Exchange Agent and shall be in such form and have such other
provisions as NBT and BSB may reasonably  specify) and (ii) instructions for use
in effecting  the  surrender of the  Certificates  in exchange for  certificates
representing  whole shares of NBT Common Stock  together  with any  dividends or
distributions  with respect  thereto and any cash in lieu of fractional  shares.
Upon surrender of a Certificate for cancellation to the Exchange Agent, together
with such letter of transmittal,  duly executed, and such other documentation as
may be required  pursuant to such  instructions,  the holder of such Certificate
shall be  entitled to receive in exchange  therefor a  certificate  representing
that number of whole shares of NBT Common Stock, which such holder has the right
to receive in respect of the Shares  formerly  represented  by such  Certificate
surrendered  pursuant to the  provisions  of this  Article I (after  taking into
account  all Shares  then held by such  holder)  and cash in lieu of  fractional
shares of NBT Common Stock (if any) to which such holder is entitled pursuant to
Section 1.09(e) and any dividends or other distributions to which such holder is
entitled  pursuant to Section 2.02(c),  and the Certificate so surrendered shall
forthwith be cancelled.  In the event of a transfer of ownership of Shares which
is not registered in the transfer records of BSB, a certificate representing the
proper number of shares of NBT Common Stock may be issued to a transferee if the
Certificate  representing  such  Shares  is  presented  to the  Exchange  Agent,
accompanied  by all documents  required to evidence and effect such transfer and
by evidence  that any  applicable  stock  transfer  taxes have been paid.  Until
surrendered as  contemplated  by this Section 1.09,  each  Certificate  shall be
deemed  at any time  after the  Effective  Time to  represent  only the right to
receive upon such surrender the  certificate  representing  shares of NBT Common
Stock,  cash in lieu of any fractional  shares of NBT Common Stock to which such
holder is  entitled  pursuant  to Section  1.09(e)  and any

                                       6

<PAGE>


dividends  or other distributions  to which  such holder is entitled pursuant to
Section 1.09(c).

                         (c) Distributions  with Respect to Unexchanged  Shares.
No dividends or other  distributions  declared or made after the Effective  Time
with  respect to NBT Common  Stock with a record date after the  Effective  Time
shall be paid to the holder of any unsurrendered Certificate with respect to the
shares of NBT Common Stock represented  thereby,  and no cash payment in lieu of
fractional  shares of NBT Common Stock (if any) shall be paid to any such holder
pursuant  to  Section  1.09(e),  until  the  holder  of such  Certificate  shall
surrender such Certificate.  Subject to the effect of applicable laws, following
surrender  of any such  Certificate,  there  shall be paid to the  holder of the
certificates  representing  whole  shares of NBT Common Stock issued in exchange
therefor,  without interest,  (i) promptly,  the amount of any cash payable with
respect  to a  fractional  share of NBT  Common  Stock to which  such  holder is
entitled  pursuant  to  Section  1.09(e)  and the amount of  dividends  or other
distributions  with a record date after the Effective Time theretofore paid with
respect to such whole shares of NBT Common  Stock,  and (ii) at the  appropriate
payment date, the amount of dividends or other distributions, with a record date
after the  Effective  Time but prior to surrender  and a payment date  occurring
after surrender, payable with respect to such whole shares of NBT Common Stock.

                         (d) No Further Rights in the Shares.  All shares of NBT
Common Stock issued upon  conversion of the Shares in accordance  with the terms
hereof  (including any cash paid pursuant to Section 1.09(e)) shall be deemed to
have been issued in full  satisfaction of all rights  pertaining to such Shares.
In accordance with Delaware Law, there shall be no appraisal rights available to
holders of BSB Common Stock or NBT Common Stock in connection with the Merger.

                         (e) No Fractional Shares.  Notwithstanding  anything to
the contrary contained herein, no certificates or scrip representing  fractional
shares of NBT Common  Stock shall be issued upon the  surrender  for exchange of
Certificates,  and such  fractional  share  interest  will not entitle the owner
thereof to vote or to any other rights of a stockholder of NBT. Each holder of a
fractional  share  interest shall be paid an amount in cash equal to the product
obtained by multiplying (i) such fractional  share interest to which such holder
(determined  after taking into account all fractional  share interests then held
by such holder) would otherwise be entitled to receive  pursuant to Section 1.08
hereof  multiplied by (ii) the actual  market value of NBT Common  Stock,  which
shall be deemed to be the average of the daily  closing  prices per share of NBT
Common Stock for the twenty consecutive  trading days on which shares of NBT are
actually  traded on the Nasdaq  National  Market ending on the third trading day
preceding the date of the Effective Time as reported by the Wall Street Journal.

                         (f)  Termination  of Exchange  Fund. Any portion of the
Exchange Fund which remains  undistributed to the stockholders of BSB for twelve
months after the Effective Time shall be delivered to NBT, upon demand,  and any
stockholders of BSB who have not theretofore  complied with this Article I shall
thereafter look only to NBT for the shares of NBT Common Stock, any cash in lieu
of fractional  shares of NBT Common Stock to which they are entitled pursuant to
Section  1.09(e) and any  dividends or other  distributions  with respect to NBT
Common Stock to which they are entitled pursuant to

                                       7

<PAGE>

Section 1.09(c). Any portion of the Exchange Fund remaining unclaimed by holders
of Shares as of a date which is  immediately  prior to such time as such amounts
would otherwise escheat to or become property of any government entity shall, to
the extent  permitted  by  applicable  Law,  become the property of NBT free and
clear of any claims or interest of any person previously entitled thereto.

                        (g) No Liability. Neither NBT, or BSB shall be liable to
any holder of Shares for any such Shares (or  dividends  or  distributions  with
respect  thereto)  or  cash  delivered  to a  public  official  pursuant  to any
abandoned property, escheat or similar Law.

                        (h) Withholding  Rights. NBT shall be entitled to deduct
and withhold from the consideration otherwise payable pursuant to this Agreement
to any holder of Shares such  amounts as NBT is required to deduct and  withhold
with respect to the making of such payment  under the Code,  or any provision of
state,  local or foreign tax law. To the extent that  amounts are so withheld by
NBT, such withheld  amounts shall be treated for all purposes of this  Agreement
as  having  been paid to the  holder of the  Shares  in  respect  of which  such
deduction and withholding were made by NBT.

                        (i) Lost, Stolen or Destroyed Certificates. In the event
any Certificate shall have been lost, stolen or destroyed, upon the making of an
affidavit  of that fact by the  person  claiming  such  Certificate  to be lost,
stolen or  destroyed  and, if  required by NBT,  the posting by such person of a
bond in such amount as NBT may reasonably  direct as indemnity against any claim
that may be made against it with respect to such Certificate, the NBT will issue
or  cause  to be  issued,  in  exchange  for  such  lost,  stolen  or  destroyed
Certificate,  the number of whole shares of NBT Common Stock and pay or cause to
be paid the amounts  deliverable in respect thereof pursuant to Sections 1.09(e)
and 1.09(c) of this Agreement.

                  SECTION 1.10.  Treatment of Stock Options.

                        (a)  At  the  Effective   Time,   each  option   granted
(including  any option  heretofore  assumed) by BSB to purchase  Shares which is
outstanding and unexercised  immediately  prior thereto shall be assumed by NBT.
Such  options  shall cease to  represent a right to acquire  Shares and shall be
converted automatically into an option to purchase shares of NBT Common Stock in
an amount and at an exercise price determined as provided below:

                             (i) the number of shares of NBT Common  Stock to be
         subject  to the  assumed  option  shall be equal to the  product of the
         number of shares of BSB Common Stock  subject to the option  originally
         granted  by  BSB,  as  previously  adjusted,  and the  Exchange  Ratio;
         provided that any fractional  shares of NBT Common Stock resulting from
         such  multiplication  shall be rounded down to the nearest whole share;
         and

                             (ii) the  exercise  price per  share of NBT  Common
         Stock under the assumed option shall be equal to the exercise price per
         share of BSB Common Stock under the option  originally  granted by BSB,
         as previously  adjusted,

                                       8

<PAGE>

divided  by  the  Exchange  Ratio,   provided  that such exercise price shall be
rounded up to the nearest whole cent.

                        (b) The  assumption  of BSB  options by NBT, as provided
herein,  shall comply with the  requirements  of Section 424(a) of the Code. The
duration and other terms of the assumed option shall be the same as the original
option  except as provided in Sections  1.10(a)(i)  and (ii) and except that all
references to BSB shall be deemed to be references to NBT.  Nothing herein shall
be construed as preventing any option holder from  exercising an option prior to
the Effective Time in accordance with the terms thereof.

                        (c) At the  Effective  Time, by virtue of the Merger and
without the need of any further corporate action,  NBT shall assume the BSB 1986
Long-Term  Incentive  and  Capital  Accumulation  Plan,  as  amended,  the  1996
Long-Term Incentive and Capital Accumulation Plan, as amended, and the Directors
Stock Option Plan (the "BSB Stock Plans"),  with the result that all obligations
of BSB under the BSB Stock Plans, including with respect to stock options issued
by BSB that are  outstanding  at the  Effective  Time under each BSB Stock Plan,
shall be obligations of NBT following the Effective Time.

                        (d) No later than 45 days after the Effective  Time, NBT
shall  prepare and file with the SEC a  registration  statement  on Form S-8 (or
another  appropriate  form)  registering  a number of shares of NBT Common Stock
equal to the number of shares  subject to the options  assumed  hereunder.  Such
registration  statement  shall be kept  effective (and the current status of the
prospectus or prospectuses required thereby shall be maintained) at least for so
long as any assumed options may remain outstanding.

                        (e) As soon as practicable after the Effective Time, NBT
shall deliver to the holders of options to purchase BSB Common Stock appropriate
notices  setting forth such holders'  rights pursuant to BSB Stock Plans and the
agreements  pursuant  to which such  options  were  issued,  and the  agreements
evidencing  the grant of such options shall be assumed by NBT and shall continue
in effect on the same terms and conditions (subject to the adjustments  required
by this Section 1.10 after giving effect to the Merger).

                        (f) Prior to the Effective  Time, NBT and BSB shall take
commercially  reasonably steps necessary to cause the transactions  contemplated
hereby  and any  other  dispositions  of  equity  securities  of BSB  (including
derivative  securities)  or  acquisitions  of NBT equity  securities  (including
derivative  securities) in connection with this Agreement by each individual who
(a) is a director or officer of NBT or (b) at the Effective  Time, will become a
director  or officer of NBT,  that may qualify  for  exemption  under Rule 16b-3
promulgated under the Securities Exchange Act of 1934, as amended (the "Exchange
Act") to be exempt thereunder.

                  SECTION 1.11.  Stock Transfer Books.

                  At the Effective  Time,  the stock transfer books of BSB shall
be closed and there  shall be no further  registration  of  transfers  of Shares
thereafter on the records of

                                       9

<PAGE>

BSB. From and after the Effective Time, the holders of Certificates  shall cease
to have any rights with  respect to such  Shares  except as  otherwise  provided
herein  or by any  Laws.  On or  after  the  Effective  Time,  any  Certificates
presented  to the  Exchange  Agent or NBT for any  reason  shall be  treated  in
accordance  with this  Article I, any cash in lieu of  fractional  shares of NBT
Common  Stock to which the  holders  thereof  are  entitled  pursuant to Section
1.09(e) and any dividends or other  distributions  to which the holders  thereof
are entitled pursuant to Section 1.09(c).

                  SECTION 1.12.   Anti-Dilution Adjustment.

                  If,  subsequent  to the date hereof and prior to the Effective
Time, NBT shall pay a stock dividend or make a distribution  on NBT Common Stock
or other  capital  stock of NBT in shares of NBT Common  Stock or other  capital
stock of NBT or any security  convertible into NBT Common Stock or other capital
stock of NBT or shall combine, subdivide,  reclassify or recapitalize its stock,
then in each such  case,  from and after the  record  date for  determining  the
stockholders entitled to receive such dividend or distribution of the securities
from such combination or subdivision, an appropriate adjustment shall be made to
the  Exchange  Ratio,  for purposes of  determining  the number of shares of NBT
Common Stock into which BSB Common Stock shall be converted  pursuant to Section
1.8 hereof.  For purposes hereof, the payment of a dividend in NBT Common Stock,
or the  distribution  on NBT Common  Stock of  securities  convertible  into NBT
Common  Stock,  shall be deemed to have  effected  an  increase in the number of
outstanding  shares of NBT  Common  Stock  equal to the  number of shares of NBT
Common Stock into which such securities shall be initially  convertible  without
the payment by the holder thereof of any consideration  other than the surrender
for cancellation of such convertible securities.

                  SECTION 1.13      Tax Consequences.

                  It is  intended  that the  Merger and Bank  Merger  shall each
constitute a  reorganization  within the meaning of Section  368(a) of the Code,
and that this Agreement shall constitute a "plan of reorganization" for purposes
of the Code.  In the event that the  requirements  of such section  would not be
satisfied  as a result of the  Merger or the Bank  Merger,  NBT and BSB will use
commercially  reasonable efforts to restructure the transaction in a manner that
would satisfy such requirements.

                                   ARTICLE II

                      REPRESENTATIONS AND WARRANTIES OF BSB

                  Except as set forth in the  disclosure  schedule  delivered by
BSB to NBT  prior  to the  execution  of this  Agreement  which  shall  identify
exceptions  by specific  Section  references  (provided  that  disclosure in one
schedule  will be deemed to satisfy  disclosure in another  schedule)  (the "BSB
Disclosure Schedule"), BSB hereby represents and warrants to NBT that:

                                       10

<PAGE>

                  SECTION  2.01.  Organization   and   Qualification   of   BSB;
Subsidiaries.

                        (a)  BSB  is  a  corporation  duly  organized,   validly
existing and in good  standing  under the laws of the State of Delaware.  BSB is
duly registered as a bank holding company with the Board of Governors of the FRB
under the BHCA. BSB has the corporate power and authority to own or lease all of
its  properties  and assets and to carry on in its  business  as it is now being
conducted and is duly licensed or qualified to do business in each  jurisdiction
in which the nature of any material business conducted by it or the character or
the  location of any material  properties  or assets owned or leased by it makes
such licensing or qualification necessary.

                        (b) BSB Bank is a New York-chartered commercial bank and
trust company duly organized and validly existing and in good standing under the
laws of the State of New York.  The deposit  accounts of BSB Bank are insured to
the applicable  limits by the Federal  Deposit  Insurance  Corporation  ("FDIC")
through the Bank Insurance Fund ("BIF") to the fullest extent  permitted by law,
and all premiums and assessments required in connection therewith have been paid
by BSB Bank. BSB Bank has the corporate  power and authority to own or lease all
of its  properties and assets and to carry on in its business as it is now being
conducted and is duly licensed or qualified to do business in each  jurisdiction
in which the nature of any material business conducted by it or the character or
the  location of any material  properties  or assets owned or leased by it makes
such licensing or qualification necessary.

                        (c) Section 2.01(c) of the BSB Disclosure  Schedule sets
forth  a true  and  complete  list  of  each of  BSB's  subsidiaries  (the  "BSB
Subsidiaries")  and all outstanding equity securities of each BSB Subsidiary and
the percentage  owned by BSB of such equity  securities.  Each BSB Subsidiary is
wholly owned,  directly or  indirectly,  by BSB.  Except as set forth in Section
2.01(c) of the BSB Disclosure Schedule,  all outstanding shares of capital stock
of BSB Subsidiaries  are validly issued,  fully paid and  nonassessable  and are
free and clear of any  lien,  claim,  charge,  option,  encumbrance,  agreement,
mortgage, pledge, security interest or restriction (each, a "Lien") with respect
thereto.  Each BSB  Subsidiary  is a  corporation,  partnership,  savings  bank,
savings and loan, bank or trust company duly incorporated or organized,  validly
existing  and  in  good  standing  under  the  laws  of  its   jurisdiction   of
incorporation or organization.

                        (d)  Each  of  BSB  and  each  BSB  Subsidiary  has  the
requisite  corporate power and authority and is in possession of all franchises,
grants, authorizations,  licenses, permits, easements,  consents,  certificates,
approvals  and orders ("BSB  Permits")  necessary to own,  lease and operate its
properties and to carry on its business as is now being conducted,  except where
the failure to be so  organized,  existing and in good  standing or to have such
power,  authority  and BSB  Permits  would not,  either  individually  or in the
aggregate, have a Material Adverse Effect (as defined in Section 8.04 hereof) on
BSB and the BSB Subsidiaries,  taken as a whole. BSB has not received any notice
of proceedings  relating to the revocation or  modification  of any BSB Permits,
except  for  any  such  revocation  or  modification  which  would  not,  either
individually or in the aggregate,  have a Material Adverse Effect on BSB and the
BSB  Subsidiaries,  taken  as a  whole.  BSB and  each  BSB  Subsidiary  is duly
qualified or licensed as a foreign  corporation  to do business,  and is in good
standing,  in each  jurisdiction  where the character of the  properties  owned,

                                       11

<PAGE>

leased  or  operated  by  it  or  the  nature  of  its  activities   makes  such
qualification  or licensing  necessary,  except for such  failures to be so duly
qualified or licensed and in good standing that would not,  either  individually
or in  the  aggregate,  have a  Material  Adverse  Effect  on BSB  and  the  BSB
Subsidiaries, taken as a whole.

                        (e) Section 2.01(e) of the BSB Disclosure  Schedule sets
forth a true,  complete  and  correct  list of all  corporations,  partnerships,
limited liability companies or other  organizations,  whether an incorporated or
unincorporated  organization (each a "Corporate Entity") of which BSB or any BSB
Subsidiary  holds or beneficially  owns 5% or more of the outstanding  shares of
any  class  of  voting  securities,  a  general  partnership  interest  or other
controlling interest,  more than 24.9% of the outstanding capital stock (whether
voting  or  nonvoting)  and  subordinated  debt or is  otherwise  deemed to be a
subsidiary within the meaning of the BHCA.

                  SECTION 2.02.  Certificate of Incorporation and Bylaws.

                  BSB and the BSB Subsidiaries have heretofore furnished or made
available to NBT a complete and correct copy of their respective Certificates of
Incorporation  and the Bylaws,  as amended or  restated.  Such  Certificates  of
Incorporation and Bylaws are in full force and effect and none of BSB or the BSB
Subsidiaries  are in  violation  of any of the  provisions  of their  respective
Certificates of Incorporation or Bylaws.

                  SECTION 2.03.  Capitalization.

                        (a)  Capitalization of BSB. The authorized capital stock
of BSB as of March  31,  2000  consists  of (i)  30,000,000  Shares,  of  which,
10,256,545 shares were issued and outstanding,  all of which are validly issued,
fully paid and  non-assessable,  and all of which have been issued in compliance
with applicable  securities  laws, and (ii) 2,500,000 shares of serial preferred
stock, par value $.01 per share ("BSB Preferred Stock"),  of which no shares are
issued and  outstanding.  Since  January 31, 2000 no shares of BSB Common  Stock
have been issued,  except for shares issued upon exercise of options outstanding
as of January 31, 2000 under the BSB Stock Plans.  As of March 31, 2000, BSB had
outstanding  963,730  options issued under the BSB Stock Plans, of which 619,346
were  exercisable.  No options have been granted since  February 28, 2000 to the
date  of this  Agreement  under  the BSB  Stock  Plans.  As of the  date of this
Agreement,  1,174,216  shares of BSB Common Stock are held as treasury  stock by
BSB.  Other than pursuant to the BSB Rights  Agreement,  the BSB Stock Plans and
the BSB Stock Option Agreement,  there are no options, warrants or other rights,
rights  of  first  refusal,  agreements,  arrangements,  or  commitments  of any
character  relating to the issued or unissued capital stock of BSB or obligating
BSB to issue or sell any shares of capital  stock of, or other equity  interests
in,  BSB.  There  are  no  obligations,  contingent  or  otherwise,  of  BSB  to
repurchase,  redeem or  otherwise  acquire any shares or to provide  funds to or
make any investment (in the form of a loan,  capital  contribution or otherwise)
in any other entity  (including any BSB  Subsidiary)  other than pursuant to the
BSB Rights Agreement.

                        (b) Capital Stock of the BSB Subsidiaries. Except as set
forth in Section 2.03(b) of the BSB Disclosure  Schedule,  there are no options,
warrants or other rights, rights of first refusal,  agreements,  arrangements or
commitments of any character relating to the issued or unissued capital stock of
the BSB  Subsidiaries  or  obligating  any

                                       12

<PAGE>

BSB  Subsidiary to issue or sell any shares of capital stock of, or other equity
interests  in any  BSB  Subsidiary.  There  are no  obligations,  contingent  or
otherwise, of any BSB Subsidiary to repurchase,  redeem or otherwise acquire any
shares of the capital stock of any BSB Subsidiary or to provide funds to or make
any investment (in the form of a loan, capital contribution or otherwise) in any
other entity.

                  SECTION 2.04.  Authority; State Takeover Laws; Certificate of
                                 Incorporation.

                        (a) BSB has the requisite  corporate power and authority
to execute and deliver this Agreement,  to perform its obligations hereunder and
to consummate the transactions  contemplated  hereby. The execution and delivery
of  this  Agreement  by BSB  and  the  consummation  by BSB of the  transactions
contemplated  hereby  have been duly and  validly  authorized  by all  necessary
corporate  action on the part of BSB and no other  corporate  proceedings on the
part of BSB are  necessary to authorize  this  Agreement  or to  consummate  the
transactions  contemplated  hereby (other than the approval of this Agreement by
the holders of a majority of the  outstanding  BSB Common Stock entitled to vote
thereon in accordance with Delaware Law and BSB's  Certificate of  Incorporation
and Bylaws).  This Agreement has been duly and validly executed and delivered by
BSB  and,  assuming  the  due  authorization,  execution  and  delivery  by NBT,
constitutes  the legal,  valid and  binding  obligation  of BSB  enforceable  in
accordance  with its terms,  except as enforcement may be limited by bankruptcy,
insolvency and similar laws affecting  creditors' rights and remedies  generally
and by general principles of equity.

                        (b) The Board of  Directors of BSB has taken all actions
necessary under Delaware Law and BSB's Certificate of  Incorporation,  including
approving the transactions  contemplated herein, to insure that the restrictions
on business  combinations  set forth in Delaware Law do not or will not apply to
this  Agreement,  the  transactions  contemplated  herein,  the BSB Stock Option
Agreement or the transactions  contemplated  therein or any transaction  between
NBT or its affiliates,  on the one hand, and BSB or its affiliates, on the other
hand,  following  the exercise of the option  granted under the BSB Stock Option
Agreement.

                  SECTION 2.05.  No Conflict; Required Filings and Consents.

                        (a)  Except as set forth in  Section  2.05(a) of the BSB
Disclosure  Schedule,  the execution and delivery of this  Agreement by BSB does
not, and the  performance  of this Agreement by BSB shall not, (i) conflict with
or  violate  the  Certificate  of  Incorporation  or  Bylaws  of BSB or any  BSB
Subsidiary, (ii) conflict with or violate any domestic (federal, state or local)
or foreign law, statute, ordinance, rule, regulation, order, judgment, decision,
writ, injunction or decree  (collectively,  "Laws") applicable to BSB or any BSB
Subsidiary,  or by which its  respective  properties  are bound or affected,  or
(iii)  result in any breach of or  constitute  a default  (or an event that with
notice or lapse of time or both would become a default) under, or give to others
any rights of termination, amendment, acceleration or cancellation of, or result
in the creation of a Lien on any of the  properties  or assets of BSB or any BSB
Subsidiary pursuant to any note, bond, mortgage, indenture, contract, agreement,
lease, license, permit, franchise or other instrument or obligation to which BSB
or any BSB  Subsidiary  is a party or by which BSB or any BSB

                                       13

<PAGE>

Subsidiary or its respective  properties  are bound or affected,  except (in the
case of clauses (ii) and (iii) of this Section  2.05(a)) for any such conflicts,
violations,  breaches,  defaults  or other  occurrences  that would not,  either
individually or in the aggregate,  have a Material Adverse Effect on BSB and the
BSB Subsidiaries, taken as a whole.

                        (b) The execution and delivery of this  Agreement by BSB
does not, and the  performance of this  Agreement by BSB shall not,  require any
consent,  approval,  authorization  or permit of, or filing with or notification
to, any governmental or regulatory authority, domestic or foreign, ("Approvals")
except  (i)  the  filing  of  applications,  notices  and  waiver  requests,  as
applicable, as to the Merger and the Bank Merger with the FRB under the BHCA and
the Office of the  Comptroller  of the Currency  ("OCC") under the National Bank
Act, 12 USC section 1 et seq.  ("National Bank Act") and the Bank Merger Act, 12
USC  1828(c)  (the  "Bank  Merger  Act"),  and  the  approval  of the  foregoing
applications,  notices  and waiver  requests;  (ii) the  filing of any  required
applications  or notices  with the OCC as to the  subsidiary  activities  of BSB
Bank, and the approval of the foregoing applications and notices; (iii) courtesy
notice of the Bank Merger to the New York State Banking Department (the "NYSBD")
and, if deemed  necessary by the NYSBD,  the filing of an  application  with the
NYSBD for NBT to become a bank holding  company  under New York law for a moment
in time and the approval of such application;  (iv) the filing with the SEC of a
registration statement on Form S-4 to register the shares of NBT Common Stock to
be issued in  connection  with the  Merger  (including  the shares of NBT Common
Stock that may be issued upon the exercise of the options referred to in Section
1.10 hereof), which will include the joint proxy statement/prospectus to be used
in soliciting the approval of BSB and NBT stockholders at special meetings to be
held in connection with this Agreement and the transactions  contemplated hereby
(such joint proxy  statement as amended or supplemented is referred to herein as
the  "Joint  Proxy  Statement"),  (v)  the  approval  of this  Agreement  by the
requisite vote of the stockholders of BSB, (vi) the approval by NBT stockholders
of (A) this  Agreement  and the  issuance  of NBT  Common  Stock  in the  Merger
pursuant  to this  Agreement  and (B) the  amendments  to NBT's  Certificate  of
Incorporation  to increase  the number of shares of NBT Common Stock that NBT is
authorized  to issue and to  provide a new name for the  Surviving  Corporation;
(vii) the filing of the  Certificate  of Merger with the  Secretary  of State of
Delaware  pursuant  to the  Delaware  Law,  (viii) the  filings  required by the
National Bank Act and OCC  regulations,  (ix) the filings  required by NASDAQ to
list additional shares; (x) such consents,  approvals,  orders,  authorizations,
registrations,  declarations  and  filings as may be required  under  applicable
federal, foreign and state securities (or related) laws and, if applicable,  the
Hart-Scott-Rodino  Antitrust  Improvements  Act of 1976,  as  amended  (the "HSR
Act"),  and the  securities or antitrust laws of any foreign  country,  and (xi)
such filings, authorizations or approvals as may be set forth in Section 2.05(b)
of the BSB  Disclosure  Schedule.  No  consents  or  approvals  of or filings or
registrations  with any  court,  administrative  agency or  commission  or other
governmental  authority or instrumentality  (each a "Governmental  Entity"),  or
with any third party are  necessary in  connection  with (1) the  execution  and
delivery by BSB of this  Agreement and the BSB Stock Option  Agreement,  (2) the
consummation  by BSB of the  Merger  and  the  other  transactions  contemplated
hereby, (3) the execution and delivery by BSB Bank of the Bank Merger Agreement,
(4)  the  performance  by BSB of its  obligations  under  the BSB  Stock  Option
Agreement;  and (5) the  consummation  by BSB  Bank of the Bank  Merger  and the
transactions  contemplated  thereby,  except,  in each case,  for such

                                       14

<PAGE>

consents, approvals  or   filings,  the failure of which to obtain will not have
a Material Adverse  Effect  on the ability of BSB to consummate the transactions
contemplated hereby.

                        (c)  BSB  hereby  represents  to  NBT  that  it  has  no
knowledge  of  any  reason  why  approval  or   effectiveness   of  any  of  the
applications,  notices or filings referred to in Section 2.05 cannot be obtained
or granted on a timely basis.

                  SECTION 2.06.  Compliance.

                  Neither BSB nor any BSB  Subsidiary is in conflict with, or in
default or violation of (i) any Law applicable to BSB or the BSB Subsidiaries or
by which any of their respective  properties are bound or affected,  or (ii) any
note, bond, mortgage,  indenture,  contract,  agreement, lease, license, permit,
franchise or other  instrument or obligation to which BSB or any BSB  Subsidiary
is a party  or by which  BSB or any BSB  Subsidiary  or any of their  respective
properties  are bound or affected,  except for any such  conflicts,  defaults or
violations  which would not,  either  individually  or in the aggregate,  have a
Material Adverse Effect on BSB and the BSB Subsidiaries, taken as a whole.

                  SECTION   2.07.  Securities  and  Banking  Reports;  Financial
                                   Statements.

                        (a) BSB and the BSB Subsidiaries  have filed,  except as
set for in Schedule 2.07 of the BSB  Disclosure  Schedule,  all material  forms,
reports,  registrations,  statements and documents, together with any amendments
required to be made with respect  thereto  that were  required to be filed since
January 1, 1995 with (i) the SEC and  (ii)(A) any self  regulatory  organization
("SRO"),  (B) any other  federal,  state or foreign  governmental  or regulatory
agency  or  authority  (collectively  with  the SEC and  the  SROs,  "Regulatory
Agencies") and (C) all other reports and  statements  (the filings made with the
entities  listed in  subclause  (ii)  (being  referred  to as  "Other  Reports")
required to be filed by BSB and any BSB  Subsidiary  since January 1, 1995,  and
paid all fees and assessments due and payable in connection  therewith,  except,
in the case of the Other  Reports,  where  failure  to file such  form,  report,
registration,  statement or document or pay such fees and assessments would not,
either  individually or in the aggregate,  have a Material Adverse Effect on BSB
and  the  BSB  Subsidiaries,   taken  as  a  whole  (all  such  forms,  reports,
registrations, statements and documents are collectively referred to as the "BSB
Reports").  The BSB Reports,  including  all BSB Reports filed after the date of
this  Agreement,  (i)  were,  or  will  be,  prepared  in  accordance  with  the
requirements  of applicable Law and (ii) did not at the time they were filed, or
will not at the time they are filed,  contain any untrue  statement  of material
fact or omit to state a material fact required to be stated therein or necessary
in order to make the statements  therein,  in the light of  circumstances  under
which they were made, not misleading.

                        (b)  Each  of  the  consolidated   financial  statements
(including,  in each case, any related notes  thereto)  contained in any filings
with the SEC since  January 1, 1995 (the "BSB SEC  Reports"),  including any BSB
SEC  Reports  filed  since  the date of this  Agreement  and  prior to or at the
Effective  Time,  have been, or will be,  prepared in accordance  with generally
accepted accounting principles applied on a consistent basis ("GAAP") throughout
the periods  involved (except as may be indicated in the notes thereto) and each
fairly  presents,  or  will  fairly  present,  in  all  material  respects,  the
consolidated  financial  position  of BSB  and the  BSB  Subsidiaries  as of the
respective  dates thereof and

                                       15

<PAGE>

the consolidated results of its operations and changes in financial position for
the periods  indicated,  except that any unaudited interim financial  statements
were or are subject to normal and recurring year-end  adjustments which were not
or are not expected to be material in amount.

                        (c)  Except  as and  to  the  extent  set  forth  on the
consolidated  balance sheet of BSB and the BSB  Subsidiaries  as of December 31,
1999, including all notes thereto (the "BSB Balance Sheet"), neither BSB nor any
BSB  Subsidiary  has any  liabilities  or  obligations  of any  nature  (whether
accrued,  absolute,  contingent or  otherwise),  except for (i)  liabilities  or
obligations  incurred in the ordinary course of business since December 31, 1999
and (ii)  liabilities or obligations  that would not, either  individually or in
the aggregate,  have a Material Adverse Effect on BSB and the BSB  Subsidiaries,
taken as a whole.

                  SECTION 2.08.  Absence of Certain Changes or Events.

                        Except as disclosed  in the BSB SEC Reports  filed prior
to the date of this  Agreement,  since  December 31,  1999,  (a) BSB and the BSB
Subsidiaries  have conducted their businesses only in the ordinary course and in
a manner consistent with past practice and (b) there has been no event which has
had,  or is  reasonably  likely  to result  in,  either  individually  or in the
aggregate, a Material Adverse Effect on BSB and the BSB Subsidiaries, taken as a
whole.

                  SECTION 2.09.  Absence of Litigation and Agreements.

                        (a) Except as  disclosed  in the BSB SEC  Reports  filed
prior to the date of this  Agreement  or set  forth in  Section  2.09 of the BSB
Disclosure  Schedule,  (i) neither BSB nor any BSB  Subsidiary is subject to any
continuing order of, or written  agreement or memorandum of understanding  with,
or  continuing  investigation  by, any federal or state savings and loan or bank
regulatory  authority or other governmental entity or regulatory  authority,  or
any  judgment,  order,  writ,  injunction,  decree or award of any  governmental
entity or regulatory  authority or arbitrator,  including,  without  limitation,
cease-and-desist or other orders which, either individually or in the aggregate,
would have or  reasonably be expected to have a Material  Adverse  Effect on BSB
and the BSB Subsidiaries,  taken as a whole; (ii) there is no claim of any kind,
action, suit, litigation, proceeding, arbitration, investigation, or controversy
affecting  BSB or the BSB  Subsidiaries  pending  or, to the  knowledge  of BSB,
threatened,  except  (A) as of the date of this  Agreement,  for  matters  which
individually  seek  damages not in excess of $500,000  and (B) as of the Closing
(as defined in Section 8.01), for matters which otherwise  cannot  reasonably be
expected to have,  either  individually or in the aggregate,  a Material Adverse
Effect on BSB and the BSB  Subsidiaries,  taken as a whole;  and (iii) there are
not  uncured  violations,  or  violations  with  respect  to  which  refunds  or
restitutions may be required,  cited in any compliance  report to BSB or the BSB
Subsidiaries as a result of the  examination by any bank  regulatory  authority,
which would have or reasonably be expected to have,  either  individually  or in
the aggregate, a Material Adverse Effect on BSB and the BSB Subsidiaries,  taken
as a whole.

                        (b) Except as set forth on the BSB  Disclosure  Schedule
at Section 2.09,  neither BSB nor any of the BSB  Subsidiaries is a party to any
written

                                       16

<PAGE>

agreement  or  memorandum  of  understanding  with,  or party to any  commitment
letter,  board  resolution  submitted  to  a  regulatory  authority  or  similar
undertaking to, or is subject to any order or directive by, or is a recipient of
any  extraordinary  supervisory  letter from any  governmental  entity or agency
which restricts materially the conduct of its business, or in any manner relates
to its capital  adequacy,  its credit or reserve  policies or its management nor
has BSB or any BSB  Subsidiary  (i) been advised by any  governmental  entity or
agency that it is  contemplating  issuing or requesting (or is  considering  the
appropriateness  of issuing or requesting)  any such order,  decree,  agreement,
memorandum of understanding, extraordinary supervisory letter, commitment letter
or similar  submission  or (ii) have  knowledge  of any  pending  or  threatened
regulatory  investigation.  Neither  BSB nor any BSB  Subsidiary  is required by
Section  32 of the  Federal  Deposit  Insurance  Act to give  prior  notice to a
Federal banking agency of the proposed addition of an individual to its board of
directors or the employment of an individual as a senior executive officer.

                  SECTION 2.10.  Employee Benefit Plans.

                  (a) Section 2.10 of the BSB  Disclosure  Schedule sets forth a
true and  complete  list of all benefit  plans,  arrangements,  commitments  and
payroll  practices  (whether or not employee  benefit plans ("BSB Plans" or "BSB
Plan") as defined in Section 3(3) of the Employee Retirement Income Security Act
of 1974,  as amended  ("ERISA"),  including,  without  limitation,  sick  leave,
vacation pay, severance pay, salary  continuation for disability,  consulting or
other  compensation  arrangements,  retirement,  deferred  compensation,  bonus,
incentive  compensation,   stock  purchase,   stock  option,  health,  including
hospitalization,  medical and dental,  life insurance and  scholarship  programs
maintained as of the date of this  Agreement or within the last six years of the
date of this  Agreement,  for the benefit of any present or former  employees of
BSB, any of the BSB  Subsidiaries  or any other entity which  together  with BSB
would be deemed a "single  employer" within the meaning of Section 4001 of ERISA
or Code Sections 414(b), (c), (m) or (o) ("BSB ERISA Affiliate") or to which BSB
or any BSB ERISA  Affiliate  has  contributed  or is or was  within the last six
years obligated to make payments.

                  (b)  With  respect  to  each  BSB  Plan,  BSB  has  heretofore
delivered or made available to NBT true, correct and complete copies of the plan
document,  trust  agreement,  if any, all  insurance  policies,  if any, and all
material  related  documents,  including,  but not limited to, (i) the actuarial
report for each BSB Plan that is a defined benefit plan,  funded welfare plan or
other plan requiring  actuarial  valuation for each of the last five years, (ii)
the most recent  determination letter from the Internal Revenue Service ("IRS"),
if such BSB Plan is intended to be a qualified  plan under Section 401(a) of the
Code,  (iii) the current  summary plan  description and each summary of material
modification,  (iv) each  Form 5500  series  filed for the  preceding  five plan
years, (v) each agreement with each fiduciary and service  provider  relating to
such BSB Plan, and (vi) all substantive correspondence relating to such BSB Plan
addressed to or received from the IRS, the U.S. Department of Labor ("DOL"), the
Pension Benefit Guaranty  Corporation ("PBGC") or any other governmental agency;
(vii) each bond  required  by Section  412 of ERISA,  each  fiduciary  liability
insurance policy, and each agreement to indemnify any fiduciary,  including each
amendment to any such document.

                                       17

<PAGE>

                  (c)   Except  as  set  forth  in  Section  2.10(c)  of the BSB
Disclosure Schedule:

                        (i) Each BSB Plan has been operated and  administered in
all material respects in compliance with the terms of its governing  document(s)
and instrument(s) and applicable Laws, including,  but not limited to, ERISA and
the Code,  and the funding,  filing,  termination,  reporting and disclosure and
continuation  coverage  obligations  pursuant  to  Title  V of the  Consolidated
Omnibus Budget Reconciliation Act of 1985, as amended ("COBRA");

                        (ii) Each BSB Plan that is  intended  to be  "qualified"
within the meaning of Section  401(a) of the Code is and from its  inception has
been so  qualified,  and any trust  created  pursuant to any such Plan is exempt
from federal  income tax under  Section  501(a) of the Code,  each such Plan has
received from the Internal Revenue Service a favorable  determination  letter to
such  effect upon which BSB or a BSB ERISA  Affiliate  is entitled to rely as to
such  matters  and which is  currently  applicable,  and neither BSB nor any BSB
ERISA Affiliate is aware of any circumstance or event which would jeopardize the
tax-qualified  status of any BSB Plan or the  tax-exempt  status of any  related
trust,  or which would cause the  imposition  of any  liability,  penalty or tax
under ERISA or the Code with respect to any BSB Plan;

                        (iii)  With  respect to each BSB Plan that is subject to
Title IV of ERISA,  the present value of accrued  benefits  under such BSB Plan,
based upon the actuarial  assumptions used by the PBGC to determine the level of
funding  required in the event of  termination  of such Plan, did not, as of its
latest valuation date,  exceed the then current value of the assets of such Plan
allocable to such accrued benefits;

                        (iv) No BSB Plan provides benefits,  including,  without
limitation,  death or medical benefits (whether or not insured), with respect to
current  or former  employees  of BSB or any BSB ERISA  Affiliate  beyond  their
retirement or other termination of employment with BSB or a BSB ERISA Affiliate,
other than coverage  mandated by applicable  Law,  death  benefits or retirement
benefits under a Plan that is an "employee  pension plan," as defined by Section
3(2) of ERISA,  deferred compensation benefits under a BSB Plan that are accrued
as liabilities on the books of BSB or any BSB ERISA  Affiliate,  or benefits the
full  cost  of  which  is  borne  by the  current  or  former  employee  (or his
beneficiary);

                        (v) No  liability  under  Title  IV of  ERISA  has  been
incurred by BSB or any BSB ERISA  Affiliate  that has not been satisfied in full
as of the date of this  Agreement,  and no  condition  exists  that  presents  a
material risk of BSB or any BSB ERISA Affiliate  incurring a material  liability
thereunder;

                        (vi) No BSB Plan is a "multiemployer plan," as such term
is  defined in Section  3(37) of ERISA,  nor has BSB or any BSB ERISA  Affiliate
ever had any  obligation  to  contribute  to a  multiemployer  plan or otherwise
incurred or assumed any liability for complete or partial withdrawal from such a
plan that is a pension plan subject to Title IV of ERISA;

                        (vii) All  contributions or other amounts payable by BSB
or any BSB ERISA  Affiliate  as of the  Effective  Time with respect to each BSB
Plan and all other

                                       18

<PAGE>

liabilities of each such entity with respect to each such BSB Plan, with respect
to current or prior plan years,  have been  paid  or  accrued in accordance with
GAAP and Section 412 of the Code;

                        (viii)  Neither BSB nor any BSB ERISA  Affiliate nor any
BSB Plan  has  engaged  in any  transaction  with  respect  to which  any of the
aforementioned  entities  could be subject to either a civil  liability or civil
penalty  assessed  pursuant to Sections 409,  501(i) or 502(l) of ERISA or a tax
imposed pursuant to Section 4975 or 4976 of the Code;

                        (ix) There are and,  for the past three years there have
been, no inquiries,  proceedings,  claims, suits pending or, to the knowledge of
BSB,  threatened  (other than routine  claims for benefits) by any  governmental
agency or authority or by any participant or beneficiary  against any of the BSB
Plans,  the assets of any of the trusts  under such Plans or the Plan sponsor or
the Plan  administrator,  or against any fiduciary of any of such BSB Plans with
respect to the design or operation of a BSB Plan;

                        (x)  Each  BSB  Plan  could  be  terminated  as  of  the
Effective Time without  material  liability to BSB or any BSB ERISA Affiliate in
excess  of the  amount  accrued  with  respect  to such  Plan  on the  financial
statements of BSB or such BSB ERISA Affiliate;

                        (xi) No BSB Plan,  either  individually or collectively,
provides  for any  payment by BSB or any BSB ERISA  Affiliate  that would not be
deductible under Code Sections  162(a)(1),  162(m) or 404, or that would,  after
giving effect to the transactions contemplated by this Agreement,  constitute an
"excess  parachute  payment"  within the meaning of Code Section 280G, nor would
the transactions  contemplated by this Agreement  accelerate the time of payment
or vesting, or increase the amount of compensation due to any employee;

                        (xii) No "accumulated  funding deficiency" as defined in
Section  302(a)(2)  of ERISA or Section 412 of the Code,  whether or not waived,
and no "unfunded  current  liability" as determined  under Section 412(l) of the
Code exists with  respect to any BSB Plan subject to Section 412 of the Code and
Section 302 of ERISA, and there are no unsatisfied  liabilities to participants,
the IRS,  the DOL,  or the PBGC as a result of the  termination  of any BSB Plan
other  than any such  liabilities  that  have not  become  due or that are being
contested in good faith;

                        (xiii) No BSB Plan has experienced a "reportable  event"
(as such term is defined in Section  4043(b) of ERISA) that is not subject to an
administrative or statutory waiver from the reporting requirement;

                        (xiv) All reports and  information  required to be filed
with the DOL,  IRS and PBGC or with plan  participants  and their  beneficiaries
with respect to each BSB Plan have been filed, and all annual reports (including
Form 5500 series) of such Plans were  certified  without  qualification  by each
Plan's  accountants and actuaries.  Any annual reports which are not yet due but
are  required to be filed with respect to a plan year which ended on or prior to
the  Effective  Date and any annual  reports which are required to be filed with
respect to current plan years shall be filed on a timely basis.


                                       19

<PAGE>

                        (xv) Any bond  required  under ERISA with respect to any
BSB Plan has been  obtained and is in full force and effect and no funds held by
or under the control of BSB are plan assets of any BSB Plan.

                  SECTION 2.11.  Material Contracts.

                  Except  as set  forth in  Section  2.11 of the BSB  Disclosure
Schedule,  as of the date of this Agreement,  neither BSB nor any BSB Subsidiary
is a  party  to  or  bound  by  (a)  any  contract  or  commitment  for  capital
expenditures  in  excess of  $500,000  for any one  project,  (b)  contracts  or
commitments  for the purchase of materials or supplies or for the performance of
services over a period of more than 60 days from the date of this  Agreement and
calling for aggregate  future  payments of $1,000,000 or more during the term of
such contract or commitment, (c) any contract which is a "material contract" (as
such term is defined in Item  601(b)(10) of Regulation  S-K of the SEC) that has
not been filed or  incorporated  by reference  in the BSB SEC  Reports,  (d) any
contract which contains  non-compete or exclusivity  provisions or  restrictions
with respect to any business or geographic  area or (e) any contract which would
prohibit  or  materially  delay  the  consummation  of the  Merger  or any other
transaction  contemplated  by  this  Agreement.   Each  contract,   arrangement,
commitment or understanding of the type described in this Section 2.11,  whether
or not set forth in Section 2.11 of the BSB Disclosure Schedule,  is referred to
herein as a "BSB Contract".  Neither BSB nor any BSB Subsidiary knows of, or has
received  notice  of,  any  violation  of any BSB  Contract  by any of the other
parties thereto, except for violations which,  individually or in the aggregate,
would not result in a Material  Adverse Effect on BSB and the BSB  Subsidiaries,
taken as a whole.

                  SECTION 2.12.  Environmental Matters.

                        (a)  Each  of  BSB  and  the  BSB   Subsidiaries  is  in
compliance in all material  respects with all applicable  federal and state laws
and  regulations   relating  to  pollution  or  protection  of  the  environment
(including  without  limitation,  laws and  regulations  relating to  emissions,
discharges,   releases  and  threatened  releases  of  Hazardous  Materials  (as
hereinafter  defined),  or otherwise  relating to the  manufacture,  processing,
distribution,  use,  treatment,  storage,  disposal,  transport  or  handling of
Hazardous Materials.

                        (b)  There  is  no  suit,  claim,  action,   proceeding,
investigation or notice pending or, to the knowledge of BSB,  threatened (or, to
the  knowledge  of BSB,  past or present  actions or events  that could form the
basis of any such suit, claim, action, proceeding,  investigation or notice), in
which BSB or any BSB Subsidiary  has been or, with respect to threatened  suits,
claims,  actions,  proceedings,  investigations  or notices  may be,  named as a
defendant (i) for alleged material noncompliance (including by any predecessor),
with any environmental  law, rule or regulation or (ii) relating to any material
release or threatened  release into the  environment of any Hazardous  Material,
occurring  at or on a  site  owned,  leased  or  operated  by  BSB  or  any  BSB
Subsidiary,  or to the  knowledge of BSB,  relating to any  material  release or
threatened release into the environment of any Hazardous Material,  occurring at
or on a site not owned, leased or operated by BSB or any BSB Subsidiary.

                                       20

<PAGE>

                        (c) During  the period of BSB's or any BSB  Subsidiary's
ownership  or operation  of any of its  properties,  there has not been to BSB's
knowledge any material release of Hazardous Materials in, on, under or affecting
any such property.

                        (d) To the  knowledge  of BSB,  neither  BSB nor any BSB
Subsidiary has made or  participated in any loan to any person who is subject to
any suit,  claim,  action,  proceeding,  investigation  or  notice,  pending  or
threatened,  with respect to (i) any alleged  material  noncompliance  as to any
property securing such loan with any environmental  law, rule or regulation,  or
(ii) the release or the threatened release into the environment of any Hazardous
Material  at a site owned,  leased or  operated  by such person on any  property
securing such loan.

                        (e) For purposes of this Agreement,  the term "Hazardous
Material"  means  any  hazardous  waste,   petroleum  product,   polychlorinated
biphenyl, chemical, pollutant, contaminant, pesticide, radioactive substance, or
other toxic material,  or other material or substance (in each such case,  other
than small quantities of such substances in retail  containers)  regulated under
any applicable  environmental or public health statute, law, ordinance,  rule or
regulation.

                  SECTION 2.13.  Taxes.

                        (a) Each of BSB and the BSB  Subsidiaries has duly filed
all Tax  Returns  required to be filed by it on or prior to the date hereof (all
such returns being accurate and complete in all material  respects) and has duly
paid or made provision on the financial  statements referred to in Sections 2.07
and 5.14 hereof in  accordance  with GAAP for the payment of all material  Taxes
which  have  been  incurred  or are due or  claimed  to be due from it by Taxing
Authorities  on or prior to the date  hereof  other than Taxes (a) which (x) are
not yet  delinquent  or (y) are being  contested  in good faith and set forth in
Section  2.13(a)  of the BSB  Disclosure  Schedule  and (b) which  have not been
finally determined. All liability with respect to the Tax Returns of BSB and the
BSB Subsidiaries has been satisfied for all years to and including 1998. The IRS
has not  notified  BSB of, or  otherwise  asserted,  that there are any material
deficiencies with respect to the federal income Tax Returns of BSB subsequent to
tax year  1995.  Except  as set  forth  in  Section  2.13 of the BSB  Disclosure
Schedule,  there are no material disputes pending,  or claims asserted for Taxes
or assessments upon BSB or any BSB Subsidiary, nor has BSB or any BSB Subsidiary
been requested to give any currently  effective  waivers extending the statutory
period of  limitation  applicable  to any federal or state income Tax Return for
any period.  In  addition,  Tax Returns  which are  accurate and complete in all
material  respects  have  been  filed  by BSB and the BSB  Subsidiaries  for all
periods  for which  returns  were due with  respect to income  tax  withholding,
Social Security and unemployment taxes and the amounts shown on such Tax Returns
to be due and payable have been paid in full or adequate  provision  therefor in
accordance  with  GAAP  has been  included  by BSB in the  financial  statements
referred  to in  Sections  2.07  hereof  and 5.14  hereof.  All BSB Tax  Returns
relating  to federal  income  taxes have been  examined by the  relevant  Taxing
Authorities, or closed without audit by applicable statutes of limitations,  and
all  deficiencies  proposed as a result of such  examinations  have been paid or
settled,  for all periods  before and  including  the  taxable  year ended 1995.
Except as set forth in Section 2.13 of the BSB Disclosure Schedule,  neither BSB
nor any BSB  Subsidiary  has consented

                                       21

<PAGE>

to any waiver or  extension  of any statute of  limitations  with respect to any
Tax.  Neither  BSB nor any BSB  Subsidiary  has made an election  under  Section
341(f) of the Code.  BSB has  provided or made  available  to NBT  complete  and
correct copies of its Tax Returns and all material correspondence and documents,
if any,  relating directly or indirectly to taxes for each taxable year or other
relevant period as to which the applicable statute of limitations has not run on
the date hereof.  For this  purpose,  "correspondence  and  documents"  include,
without limitation, amended Tax Returns, claims for refunds, notices from Taxing
Authorities of proposed changes or adjustments to Taxes or Tax Returns, consents
to  assessment  or collection  of Taxes,  acceptances  of proposed  adjustments,
closing agreements, rulings and determination letters and requests therefor, and
all other written  communications to or from Taxing Authorities  relating to any
material Tax liability of BSB or any BSB Subsidiary.  BSB will not be a "foreign
person"  as  that  term  is used in ss.  1.1445-2  of the  Treasury  Regulations
promulgated  under the  Code.  BSB Bank is not a "United  States  real  property
holding corporation" within meaning of ss. 897 of the Code and was not a "United
States  real  property  holding  corporation"  on any  "determination  date" (as
defined in ss. 1.897-2(c) of such Regulations) that occurred during any relevant
period.

                           (b)      For purposes of this Agreement:

                  "Tax" means any tax (including  any income tax,  capital gains
tax,  value-added tax, sales tax,  property tax, gift tax, or estate tax), levy,
assessment, tariff, duty (including any customs duty), deficiency, or other fee,
and any related charge or amount  (including  any fine,  penalty,  interest,  or
addition to tax), imposed,  assessed,  or collected by or under the authority of
any Taxing  Authority or payable  pursuant to any  tax-sharing  agreement or any
other  contract  relating  to the  sharing  or  payment  of any such tax,  levy,
assessment, tariff, duty, deficiency, or fee.

                  "Tax  Return"  means any  return  (including  any  information
return),  report,  statement,  schedule,  notice,  form,  or other  document  or
information  filed  with or  submitted  to,  or  required  to be  filed  with or
submitted  to,  any  Taxing  Authority  in  connection  with the  determination,
assessment,  collection,  or  payment  of any  Tax  or in  connection  with  the
administration,  implementation,  or enforcement of or compliance  with any law,
regulation or other legal requirement relating to any Tax.

                  "Taxing Authority" means any:

                             (i) nation,  state,  county,  city, town,  village,
              district, or other jurisdiction of any nature;

                             (ii) federal, state, local, municipal,  foreign, or
              other government;

                             (iii) governmental or quasi-governmental  authority
              of  any  nature  (including  any  governmental   agency,   branch,
              department, official, or entity and any court or other tribunal);

                             (iv) multi-national organization or body; or

                                       22

<PAGE>

                             (v) body exercising,  or entitled to exercise,  any
              administrative,    executive,   judicial,   legislative,   police,
              regulatory, or taxing authority or power of any nature.

                  SECTION 2.14.  Affiliates.

                  Each  director,  executive  officer and other person who is an
"affiliate"  (for  purposes  of Rule 145 under the  Securities  Act of 1933,  as
amended (the  "Securities  Act"),  and for purposes of qualifying the Merger for
"pooling-of-interests" accounting treatment) of BSB is listed at Section 2.14 of
the BSB Disclosure Schedule,  and except as indicated thereon,  each such person
has  delivered  to NBT  concurrently  with the  execution of this  Agreement,  a
stockholder  agreement  in the form of  Exhibit F hereto  (the "BSB  Stockholder
Agreement").

                  SECTION 2.15.  Derivative Instruments.

                  All  swap,  forward,  future,  option,  cap,  floor or  collar
financial   contracts,   and  any  other  interest  rate  protection   contracts
("Derivative  Instruments")  to which BSB or any BSB Subsidiary is a party or to
which any of their  properties or assets may be subject were entered into in the
ordinary  course of business and, to the  knowledge of BSB, in  accordance  with
prudent banking practice and applicable rules, regulations,  and policies of the
regulatory  agencies  and  with   counterparties   believed  to  be  financially
responsible  at the time and, to the  knowledge  of BSB, are legal,  valid,  and
binding obligations enforceable in accordance with their terms (except as may be
limited by bankruptcy, insolvency,  moratorium,  reorganization, or similar laws
affecting the rights of creditors  generally,  and the availability of equitable
remedies),  and, to the knowledge of BSB, are in full force and effect.  BSB and
each BSB  Subsidiary  has duly  performed  in all  material  respects all of its
obligations under any such Derivative Instruments,  and to the knowledge of BSB,
there are no breaches,  violations,  or defaults or allegations or assertions of
such by any  party  thereunder  except  for any such  breaches,  violations,  or
defaults or allegations or assertions  which would not,  individually  or in the
aggregate, have a Material Adverse Effect on BSB and the BSB Subsidiaries, taken
as a whole.

                  SECTION 2.16.  Regulatory Approvals.

                  BSB is not aware of any aspect of, or issues  relating to, its
or the  BSB  Subsidiaries'  operations  and  business  that  would  prevent  the
condition of Closing set forth in Section 6.01(c) from being satisfied.

                  SECTION 2.17.  Brokers.

                  Except as  contemplated by or referenced in the March 17, 2000
letter agreement  between Keefe,  Bruyette & Woods, Inc. ("KBW") and BSB, a true
and  complete  copy of which BSB has  delivered  to NBT,  no  broker,  finder or
investment  banker  is  entitled  to any  brokerage,  finder's  or other  fee or
commission in connection  with the  transactions  contemplated by this Agreement
based upon arrangements made by or on behalf of BSB or any BSB Subsidiary.

                                       23

<PAGE>


                  SECTION 2.18.  Pooling of Interests and Tax Matters.

                  Neither  BSB  nor,  to  the  knowledge  of  BSB,  any  of  its
affiliates  (as defined in Section 2.14) has through the date of this  Agreement
taken or agreed to take any action that would  prevent NBT from  accounting  for
the business  combination  to be effected by the Merger and the Bank Merger as a
pooling of interests in  accordance  with GAAP or would  prevent the Merger from
qualifying  as a  reorganization  under Section  368(a) of the Code.  BSB has no
reason to believe  that the Merger will not qualify as a pooling of interests or
as a reorganization under Section 368(a) of the Code.

                  SECTION 2.19.  Vote Required.

                  The requisite affirmative vote of the holders of a majority of
the  outstanding  BSB Common Stock entitled to vote with respect to the approval
of this  Agreement  is the only  vote of the  holders  of any class or series of
BSB's capital stock required in connection with the Merger.

                  SECTION 2.20.  Fairness Opinion.

                  BSB has  received an opinion  from KBW on or prior to the date
of this  Agreement  to the  effect  that,  as of the date of such  opinion,  the
Exchange  Ratio is fair to the  stockholders  of BSB, from a financial  point of
view ("BSB Fairness  Opinion") and KBW has consented to the inclusion of the BSB
Fairness Opinion in the Registration Statement.

                  SECTION 2.21 Rights Agreement.

                  The  Board of  Directors  of BSB has taken  such  action as is
necessary to render the Series A junior  participating  preferred stock purchase
rights of BSB under the BSB Rights Agreement  inapplicable to the Merger and the
other transactions contemplated by this Agreement.

                                   ARTICLE III

                      REPRESENTATIONS AND WARRANTIES OF NBT

                  Except as set forth in the  disclosure  schedule  delivered by
NBT to BSB  prior  to the  execution  of this  Agreement  (the  "NBT  Disclosure
Schedule")  which  shall  identify  exceptions  by specific  Section  references
(provided that  disclosure in one schedule will be deemed to satisfy  disclosure
in another schedule), NBT hereby represents and warrants to BSB that:

                  SECTION   3.01.  Organization  and  Qualification   of    NBT;
                                   Subsidiaries.

                        (a)  NBT  is  a  corporation  duly  organized,   validly
existing and in good  standing  under the laws of the State of Delaware.  NBT is
duly registered as a bank holding company with the Board of Governors of the FRB
under the BHCA. NBT has the corporate power and authority to own or lease all of
its  properties  and assets and to carry on in its  business  as it is now being
conducted and is duly licensed or qualified to do

                                       24

<PAGE>

business  in each  jurisdiction  in which the  nature of any  material  business
conducted by it or the  character or the location of any material  properties or
assets owned or leased by it makes such licensing or qualification necessary.

                        (b) NBT Bank is a  national  association  organized  and
validly  existing and in good standing under the laws of the United States.  The
deposit  accounts  of NBT Bank are  insured by the FDIC  through  the BIF to the
fullest extent  permitted by law, and all premiums and  assessments  required in
connection  therewith  have been paid by NBT  Bank.  NBT Bank has the  corporate
power and  authority  to own or lease all of its  properties  and  assets and to
carry on in its business as it is now being  conducted  and is duly  licensed or
qualified  to do  business  in each  jurisdiction  in which  the  nature  of any
material  business  conducted  by it or the  character  or the  location  of any
material  properties  or assets  owned or leased by it makes such  licensing  or
qualification necessary.

                        (c) Section 3.01(c) of the NBT Disclosure  Schedule sets
forth  a true  and  complete  list  of  each of  NBT's  subsidiaries  (the  "NBT
Subsidiaries"), all outstanding equity securities of each NBT Subsidiary and the
percentages  owned by NBT of such  equity  securities.  Except  as set  forth in
Section  3.01(c) of the NBT Disclosure  Schedule,  each NBT Subsidiary is wholly
owned, directly or indirectly, by NBT. Except as set forth in Section 3.01(c) of
the NBT Disclosure Schedule,  all outstanding shares of capital stock of the NBT
Subsidiaries are validly issued,  fully paid and  nonassessable and are free and
clear of any Lien, with respect  thereto.  Each NBT Subsidiary is a corporation,
partnership,  savings  bank,  savings  and  loan,  bank or  trust  company  duly
incorporated or organized  validly  existing and in good standing under the laws
of its jurisdiction of incorporation or organization.

                        (d)  Each  of  NBT  and  each  NBT  Subsidiary  has  the
requisite  corporate power and authority and is in possession of all franchises,
grants, authorizations,  licenses, permits, easements,  consents,  certificates,
approvals  and orders ("NBT  Permits")  necessary to own,  lease and operate its
properties  and to carry on its  business as it is now being  conducted,  except
where the failure to be so  organized,  existing and in good standing or to have
such power,  authority and NBT Permits would not, either  individually or in the
aggregate, have a Material Adverse Effect on NBT and the NBT Subsidiaries, taken
as a whole.  NBT has not  received  any notice of  proceedings  relating  to the
revocation or modification of any NBT Permits, except for any such revocation or
modification  which would not, either  individually or in the aggregate,  have a
Material Adverse Effect on NBT and the NBT  Subsidiaries,  taken as a whole. NBT
and each NBT Subsidiary is duly  qualified or licensed as a foreign  corporation
to do  business,  and is in  good  standing,  in  each  jurisdiction  where  the
character of the properties owned, leased or operated by it or the nature of its
activities  makes such  qualification  or licensing  necessary,  except for such
failures to be so duly  qualified  or licensed and in good  standing  that would
not, either individually or in the aggregate,  have a Material Adverse Effect on
NBT and the NBT Subsidiaries, taken as a whole.

                        (e) Section 3.01(e) of the NBT Disclosure  Schedule sets
forth a true,  complete and correct list of all Corporate  Entities of which NBT
or any NBT Subsidiary  holds or beneficially  owns 5% or more of the outstanding
shares of any class of voting  securities,  a general  partnership  interest  or
other  controlling  interest,  more than

                                       25

<PAGE>

24.9% of the  outstanding  capital  stock  (whether  voting  or  nonvoting)  and
subordinated  debt or is otherwise deemed to be a subsidiary  within the meaning
of the BHCA.

                  SECTION 3.02.  Certificate of Incorporation and Bylaws.

                  NBT and the NBT Subsidiaries have heretofore furnished or made
available to BSB a complete and correct copy of their respective Certificates of
Incorporation  and  Bylaws,  as  amended  or  restated.   Such  Certificates  of
Incorporation  and  Bylaws  are in full force and effect and none of NBT nor any
NBT  Subsidiary  is in  violation  of any of the  provisions  of its  respective
Certificate of Incorporation or Bylaws.

                  SECTION 3.03.  Capitalization.

                        (a)  Capitalization of NBT. The authorized capital stock
of NBT as of March 31,  2000  consists  of (i)  30,000,000  shares of NBT Common
Stock, of which 18,623,435  shares were issued and 18,100,868 were  outstanding,
all of which are,  and the shares of NBT Common  Stock to be issued  pursuant to
the  Merger,   when  so  issued  will  be,  validly   issued,   fully  paid  and
non-assessable,  and all of which have been or will be issued in compliance with
applicable  securities  laws, and (ii) 2,500,000  shares of preferred stock, par
value $0.01 per share ("NBT Preferred Stock"), of which no shares are issued and
outstanding.  Since  February 17, 2000,  no shares of NBT Common Stock have been
issued. As of March 31, 2000, NBT had outstanding 1,172,575 options issued under
the NBT Stock Plans (as defined below),  of which 560,400 were  exercisable.  No
options have been granted since  January 24, 2000 to the date of this  Agreement
under the NBT Stock Plans. As of the date of this  Agreement,  522,567 shares of
the NBT Common Stock are held as treasury  stock by NBT.  Other than pursuant to
the NBT Rights Agreement,  the NBT Stock Plans, the Agreement and Plan of Merger
with Pioneer American Holding Company Corp.,  dated December 7, 1999, as amended
as of March 7, 2000, the Agreement and Plan of  Reorganization  with M. Griffith
Inc.,  dated March 15,  2000,  the NBT Stock  Option  Agreement,  the 1994 Stock
Option  Plan of Lake Ariel  Bancorp,  Inc.,  the 1997 Stock  Option Plan of Lake
Ariel  Bancorp,  Inc.,  employment  agreements  between NBT and each of Daryl R.
Forsythe,  Joe C.  Minor,  Martin  A.  Dietrich,  John R.  Bradley,  and John G.
Martines (the "NBT Stock  Plans"),  and dividend  reinvestment,  employee  stock
purchase  and  similar  plans of NBT,  there are no  options,  warrants or other
rights, rights of first refusal, agreements, arrangements, or commitments of any
character  relating to the issued or unissued capital stock of NBT or obligating
NBT to issue or sell any shares of capital  stock of, or other equity  interests
in, NBT. Except as set forth in Schedule 3.03(b) of the NBT Disclosure Schedule,
there are no obligations,  contingent or otherwise, of NBT to repurchase, redeem
or otherwise  acquire any shares of NBT Common  Stock or to provide  funds to or
make any investment (in the form of a loan,  capital  contribution or otherwise)
in any other entity  (including any NBT  Subsidiary)  other than pursuant to the
Rights Agreement, dated as of November 15, 1994, by and between NBT Bank and AST
("NBT Rights Agreement").

                        (b) Capital Stock of the NBT Subsidiaries. Except as set
forth in Section 3.03(b) of the NBT Disclosure  Schedule,  there are no options,
warrants or other rights, rights of first refusal,  agreements,  arrangements or
commitments of any character relating to the issued or unissued capital stock of
the NBT  Subsidiaries  or  obligating  any

                                       26

<PAGE>

NBT  Subsidiary to issue or sell any shares of capital stock of, or other equity
interests in any NBT  Subsidiary.  Except as set forth in Section 3.03(b) of the
NBT Disclosure Schedule,  there are no obligations,  contingent or otherwise, of
any NBT Subsidiary to repurchase,  redeem or otherwise acquire any shares of the
capital  stock  of any  NBT  Subsidiary  or to  provide  funds  to or  make  any
investment  (in the form of a loan,  capital  contribution  or otherwise) in any
other entity.

                  SECTION 3.04.  Authority.

                        (a) NBT has the requisite  corporate power and authority
to execute and deliver this Agreement,  to perform its obligations hereunder and
to consummate the transactions  contemplated  hereby. The execution and delivery
of  this  Agreement  by NBT  and  the  consummation  by NBT of the  transactions
contemplated  hereby  have been duly and  validly  authorized  by all  necessary
corporate  action on the part of NBT and no other  corporate  proceedings on the
part of NBT are  necessary to authorize  this  Agreement  or to  consummate  the
transactions  contemplated  hereby (other than, with respect to the Merger,  the
approval by the holders of a majority  of the  outstanding  shares of NBT Common
Stock  entitled to vote  thereon of (A) this  Agreement  and the issuance of NBT
Common Stock in the Merger  pursuant to this  Agreement  and (B)  amendments  to
NBT's  Certificate  of  Incorporation  to  increase  the number of shares of NBT
Common Stock that NBT is  authorized  to issue and to provide a new name for the
Surviving Corporation,  in accordance with Delaware Law, the rules of the Nasdaq
Stock Market and NBT's Certificate of Incorporation and Bylaws).  This Agreement
has been duly and validly  executed  and  delivered  by NBT and assuming the due
authorization,  execution and delivery by BSB,  constitutes the legal, valid and
binding  obligation of NBT enforceable in accordance  with its terms,  except as
enforcement may be limited by bankruptcy,  insolvency and similar laws affecting
creditors' rights and remedies generally and by general principles of equity.

                        (b) The Board of  Directors of NBT has taken all actions
necessary under Delaware Law and NBT's Certificate of  Incorporation,  including
approving the transactions  contemplated herein, to insure that the restrictions
on business  combinations  set forth in Delaware Law do not or will not apply to
this  Agreement,  the  transactions  contemplated  herein,  the NBT Stock Option
Agreement or the transactions  contemplated  therein or any transaction  between
BSB or its affiliates,  on the one hand, and NBT or its affiliates, on the other
hand,  following  the exercise of the option  granted under the NBT Stock Option
Agreement.

                  SECTION 3.05.  No Conflict; Required Filings and Consents.

                        (a)  Except as set forth in  Section  3.05(a) of the NBT
Disclosure  Schedule,  the execution and delivery of this  Agreement by NBT does
not, and the  performance  of this Agreement by NBT shall not, (i) conflict with
or  violate  the  Certificate  of  Incorporation  or  Bylaws  of NBT or any  NBT
Subsidiary,  (ii) conflict with or violate any Laws applicable to NBT or any NBT
Subsidiary,  or by which its  respective  properties  are bound or affected,  or
(iii)  result in any breach of or  constitute  a default  (or an event that with
notice or lapse of time or both would become a default) under, or give to others
any rights of termination, amendment, acceleration or cancellation of, or result
in the creation

                                       27

<PAGE>

of a Lien  on any of the  properties  or  assets  of NBT or any  NBT  Subsidiary
pursuant to any note, bond, mortgage,  indenture,  contract,  agreement,  lease,
license, permit, franchise or other instrument or obligation to which NBT or any
NBT  Subsidiary  is a  party  or by  which  NBT or  any  NBT  Subsidiary  or its
respective properties are bound or affected, except (in the case of clauses (ii)
and (iii) of this Section 3.05(a)) for any such conflicts, violations, breaches,
defaults or other  occurrences  that would not,  either  individually  or in the
aggregate, have a Material Adverse Effect on NBT and the NBT Subsidiaries, taken
as a whole.

                        (b) The execution and delivery of this  Agreement by NBT
does not, and the  performance of this  Agreement by NBT shall not,  require any
Approvals,  except (i) the filing of applications,  notices and waiver requests,
as applicable,  as to the Merger and the Bank Merger with the FRB under the BHCA
and OCC under the National Bank Act and the Bank Merger Act, and the approval of
the foregoing applications,  notices and waiver requests; (ii) the filing of any
required applications or notices with the OCC as to the subsidiary activities of
BSB Bank,  and the approval of the  foregoing  applications  and notices;  (iii)
courtesy notice of the Bank Merger to the NYSBD and, if deemed  necessary by the
NYSBD,  the  filing  of an  application  with the NYSBD for NBT to become a bank
holding company under New York law for a moment in time and the approval of such
application;  (iv) the filing with the SEC of a  registration  statement on Form
S-4 to register the shares of NBT Common Stock to be issued in  connection  with
the Merger (including the shares of NBT Common Stock that may be issued upon the
exercise of the options referred to in Section 1.10 hereof),  which will include
the Joint Proxy  Statement,  (v) the approval of this Agreement by the requisite
vote of the  stockholders  of BSB, (vi) the approval by NBT  stockholders of (A)
this  Agreement  and the issuance of NBT Common Stock in the Merger  pursuant to
this Agreement and (B) the amendments to NBT's  Certificate of  Incorporation to
increase  the number of shares of NBT Common  Stock  that NBT is  authorized  to
issue and to provide a new name for the Surviving Corporation;  (vii) the filing
of the Certificate of Merger with the Secretary of State of Delaware pursuant to
the Delaware Law,  (viii) the filings  required by the National Bank Act and OCC
Regulations,  (ix) the filings required by NASDAQ to list additional shares, (x)
such consents, approvals, orders,  authorizations,  registrations,  declarations
and  filings as may be  required  under  applicable  federal,  foreign and state
securities (or related) laws and, if applicable, the HSR Act, and the securities
or antitrust laws of any foreign country, and (xi) such filings,  authorizations
or  approvals  as may be set  forth in  Section  3.05(b)  of the NBT  Disclosure
Schedule.  No  consents or  approvals  of or filings or  registrations  with any
Governmental  Entity,  or with any third party are necessary in connection  with
(1) the execution and delivery by NBT of this Agreement and the NBT Stock Option
Agreement,  (2) the consummation by NBT of the Merger and the other transactions
contemplated  hereby,  (3) the  execution  and  delivery by NBT Bank of the Bank
Merger  Agreement,  (4) the performance by NBT of its obligations  under the NBT
Stock Option Agreement;  and (5) the consummation by NBT Bank of the Bank Merger
and the  transactions  contemplated  thereby,  except,  in each  case,  for such
consents,  approvals or filings,  the failure of which to obtain will not have a
Material  Adverse  Effect on the ability of NBT to consummate  the  transactions
contemplated hereby.

                        (c)  NBT  hereby  represents  to  BSB  that  it  has  no
knowledge  of  any  reason  why  approval  or   effectiveness   of  any  of  the
applications,  notice or filings  referred to in Section 3.05 cannot be obtained
or granted on a timely basis.


                                       28

<PAGE>

                  SECTION 3.06.  Compliance.

                  Neither NBT nor any NBT  Subsidiary is in conflict with, or in
default or violation of, (i) any Law  applicable to NBT or the NBT  Subsidiaries
or by which any of their  respective  properties are bound or affected,  or (ii)
any note,  bond,  mortgage,  indenture,  contract,  agreement,  lease,  license,
permit,  franchise or other  instrument  or  obligation  to which NBT or any NBT
Subsidiary  is a party or by  which  NBT or any NBT  Subsidiary  or any of their
respective  properties  are bound or  affected,  except for any such  conflicts,
defaults or violations which would not, either individually or in the aggregate,
have a  Material  Adverse  Effect  on NBT and the NBT  Subsidiaries,  taken as a
whole.

                  SECTION  3.07.   Securities  and  Banking  Reports;  Financial
                                   Statements.

                        (a) NBT and the NBT Subsidiaries have filed all material
forms,  reports,  registrations,  statements  and  documents,  together with any
amendments  required to be made with respect  thereto  that were  required to be
filed since January 1, 1995 with the  Regulatory  Agencies and all Other Reports
required to be filed by NBT and any NBT  Subsidiary  since January 1, 1995,  and
paid all fees and assessments due and payable in connection  therewith,  except,
in the case of the Other  Reports,  where  failure  to file such  form,  report,
registration,  statement or document or pay such fees and assessments would not,
either  individually or in the aggregate,  have a Material Adverse Effect on NBT
and the NBT  Subsidiaries,  taken as a whole (all such  reports,  registrations,
statements and documents are collectively referred to as the "NBT Reports"). The
NBT Reports,  including all NBT Reports filed after the date of this  Agreement,
(i) were, or will be, prepared in accordance with the requirements of applicable
Law and (ii) did not at the time they were  filed,  or will not at the time they
are filed,  contain any untrue  statement  of  material  fact or omit to state a
material  fact  required to be stated  therein or necessary in order to make the
statements  therein,  in the light of the  circumstances  under  which they were
made, not misleading.

                        (b)  Each  of  the  consolidated   financial  statements
(including,  in each case, any related notes  thereto)  contained in any filings
with the SEC since  January 1, 1995 (the "NBT SEC  Reports"),  including any NBT
SEC  Reports  filed  since  the date of this  Agreement  and  prior to or at the
Effective  Time,  have  been,  or will be,  prepared  in  accordance  with  GAAP
throughout  the  periods  involved  (except  as may be  indicated  in the  notes
thereto)  and each fairly  presents,  or will fairly  present,  in all  material
respects, the consolidated financial position of NBT and the NBT Subsidiaries as
of the respective dates thereof and the  consolidated  results of its operations
and changes in  financial  position for the periods  indicated,  except that any
unaudited  interim  financial  statements  were or are  subject  to  normal  and
recurring year-end adjustments which were not or are not expected to be material
in amount.

                        (c)  Except  as and  to  the  extent  set  forth  on the
consolidated  balance sheet of NBT and the NBT  Subsidiaries  as of December 31,
1999, including all notes thereto (the "NBT Balance Sheet"), neither NBT nor any
NBT  Subsidiary  has any  liabilities  or  obligations  of any  nature  (whether
accrued,  absolute,  contingent or  otherwise),  except for (i)  liabilities  or
obligations  incurred in the ordinary course of business since December 31, 1999
or by operation of law in the merger with Lake Ariel  Bancorp,  Inc. on

                                       29

<PAGE>


February 17, 2000 and (ii)  liabilities  or obligations  that would not,  either
individually or in the aggregate,  have a Material Adverse Effect on NBT and the
NBT Subsidiaries, taken as a whole.

                  SECTION 3.08.  Absence of Certain Changes or Events.

                        Except as disclosed  in the NBT SEC Reports  filed prior
to the date of this  Agreement,  since  December 31,  1999,  (a) NBT and the NBT
Subsidiaries  have conducted their businesses only in the ordinary course and in
a manner consistent with past practice and (b) there has been no event which has
had,  or is  reasonably  likely  to result  in,  either  individually  or in the
aggregate, a Material Adverse Effect on NBT and the NBT Subsidiaries, taken as a
whole.

                  SECTION 3.09.  Absence of Litigation and Agreements.

                        (a) Except as  disclosed  in the NBT SEC  Reports  filed
prior to the date of this  Agreement  or set  forth in  Section  3.09 of the NBT
Disclosure  Schedule,  (i) neither NBT nor any NBT  Subsidiary is subject to any
continuing order of, or written  agreement or memorandum of understanding  with,
or  continuing  investigation  by, any federal or state savings and loan or bank
regulatory  authority or other governmental entity or regulatory  authority,  or
any  judgment,  order,  writ,  injunction,  decree or award of any  governmental
entity or regulatory  authority or arbitrator,  including,  without  limitation,
cease-and-desist or other orders which, either individually or in the aggregate,
would have or  reasonably be expected to have a Material  Adverse  Effect on NBT
and the NBT Subsidiaries,  taken as a whole; (ii) there is no claim of any kind,
action, suit, litigation, proceeding, arbitration, investigation, or controversy
affecting  NBT or the NBT  Subsidiaries  pending  or, to the  knowledge  of NBT,
threatened,  except  (A) as of the date of this  Agreement,  for  matters  which
individually  seek  damages not in excess of $500,000 and (B) as of the Closing,
for matters  which  otherwise  cannot  reasonably  be  expected to have,  either
individually or in the aggregate,  a Material  Adverse Effect on NBT and the NBT
Subsidiaries,  taken as a whole; and (iii) there are not uncured violations,  or
violations with respect to which refunds or restitutions may be required,  cited
in any  compliance  report  to NBT or the NBT  Subsidiaries  as a result  of the
examination by any bank regulatory authority,  which would have or reasonably be
expected to have,  either  individually or in the aggregate,  a Material Adverse
Effect on NBT and the NBT Subsidiaries, taken as a whole.

                        (b) Except as set forth on the NBT  Disclosure  Schedule
at Section 3.09,  neither NBT nor any of the NBT  Subsidiaries is a party to any
written  agreement  or  memorandum  of  understanding  with,  or  party  to  any
commitment  letter,  board  resolution  submitted to a  regulatory  authority or
similar  undertaking  to, or is  subject to any order or  directive  by, or is a
recipient of any extraordinary  supervisory letter from any governmental  entity
or agency which  restricts  materially  the conduct of its  business,  or in any
manner relates to its capital  adequacy,  its credit or reserve  policies or its
management  nor  has  NBT  or  any  NBT  Subsidiary  (i)  been  advised  by  any
governmental entity or agency that it is contemplating issuing or requesting (or
is considering  the  appropriateness  of issuing or requesting)  any such order,
decree,  agreement,  memorandum  of  understanding,   extraordinary  supervisory
letter,  commitment  letter or similar

                                       30

<PAGE>

submission  or (ii) have  knowledge  of any  pending  or  threatened  regulatory
investigation.  Neither NBT nor any NBT  Subsidiary is required by Section 32 of
the Federal  Deposit  Insurance  Act to give prior  notice to a Federal  banking
agency of the proposed  addition of an  individual  to its board of directors or
the employment of an individual as a senior executive officer.

                  SECTION 3.10.  Employee Benefit Plans.

                  (a) Section 3.10 of the NBT  Disclosure  Schedule sets forth a
true and  complete  list of all benefit  plans,  arrangements,  commitments  and
payroll practices (whether or not employee benefit plans ("NBT Plans" or "Plan")
as defined in Section 3(3) of ERISA, including,  without limitation, sick leave,
vacation pay, severance pay, salary  continuation for disability,  consulting or
other  compensation  arrangements,  retirement,  deferred  compensation,  bonus,
incentive  compensation,   stock  purchase,   stock  option,  health,  including
hospitalization,  medical and dental,  life insurance and  scholarship  programs
maintained as of the date of this Agreement, or within the last six years of the
date of this  Agreement,  for the benefit of any present or former  employees of
NBT, any of the NBT  Subsidiaries  or any other entity which  together  with NBT
would be deemed a "single  employer" within the meaning of Section 4001 of ERISA
or Code Section 414(b),  (c), (m) or (o) ("NBT ERISA Affiliate") or to which NBT
or any NBT ERISA  Affiliate  has  contributed  or is or was  within the last six
years obligated to make payments.

                  (b)  With  respect  to  each  NBT  Plan,  NBT  has  heretofore
delivered or made available to BSB true, correct and complete copies of the plan
document,  trust  agreement,  if any, all  insurance  policies,  if any, and all
material  related  documents,  including,  but not limited to, (i) the actuarial
report for each NBT Plan that is a defined benefit plan,  funded welfare plan or
other plan requiring  actuarial  valuation for each of the last five years, (ii)
the most recent  determination letter from the IRS, if such NBT Plan is intended
to be a  qualified  plan under  Section  401(a) of the Code,  (iii) the  current
summary plan  description and each summary of material  modification,  (iv) each
Form 5500 series filed for the  preceding  five plan years,  (v) each  agreement
with each fiduciary and service provider relating to such NBT Plan, and (vi) all
substantive  correspondence  relating to such NBT Plan  addressed to or received
from the IRS, the DOL, PBGC or any other  governmental  agency,  (vii) each bond
required by Section 412 of ERISA, each fiduciary liability insurance policy, and
each agreement to indemnify any fiduciary,  including each amendment to any such
document.

                  (c)  Except  as set  forth  in  Section  3.10(c)  of  the  NBT
Disclosure Schedule:

                       (i) Each NBT Plan has been operated and  administered  in
all material respects in compliance with the terms of its governing  document(s)
and instrument(s) and applicable Laws, including,  but not limited to, ERISA and
the Code,  and the funding,  filing,  termination,  reporting and disclosure and
continuation coverage obligations pursuant to Title V of COBRA;

                       (ii) Each NBT Plan  that is  intended  to be  "qualified"
within the meaning of Section  401(a) of the Code is and from its  inception has
been so  qualified,  and any trust  created  pursuant to any such Plan is exempt
from federal  income tax under  Section  501(a) of the Code,  each such Plan has
received from the IRS a favorable

                                       31

<PAGE>


determination  letter to such effect upon which NBT or an NBT ERISA Affiliate is
entitled  to rely as to such  matters  and which is  currently  applicable,  and
neither NBT nor any NBT ERISA  Affiliate is aware of any  circumstance  or event
which  would  jeopardize  the  tax-qualified  status  of  any  NBT  Plan  or the
tax-exempt  status of any related trust,  or which would cause the imposition of
any  liability,  penalty or tax under ERISA or the Code with  respect to any NBT
Plan;

                        (iii)  With  respect to each NBT Plan that is subject to
Title IV of ERISA,  the present value of accrued  benefits  under such NBT Plan,
based upon the actuarial  assumptions used by the PBGC to determine the level of
funding  required in the event of  termination  of such Plan, did not, as of its
latest valuation date,  exceed the then current value of the assets of such Plan
allocable to such accrued benefits;

                        (iv) No NBT Plan provides benefits,  including,  without
limitation,  death or medical benefits (whether or nor insured), with respect to
current  or former  employees  of NBT or any NBT ERISA  Affiliate  beyond  their
retirement  or  other  termination  of  employment  with  NBT  or an  NBT  ERISA
Affiliate,  other than coverage  mandated by applicable  Law,  death benefits or
retirement  benefits under a Plan that is an "employee pension plan," as defined
by Section 3(2) of ERISA,  deferred compensation benefits under an NBT Plan that
are accrued as  liabilities on the books of NBT or any NBT ERISA  Affiliate,  or
benefits  the full cost of which is borne by the current or former  employee (or
his beneficiary);

                        (v) No  liability  under  Title  IV of  ERISA  has  been
incurred by NBT or any NBT ERISA  Affiliate  that has not been satisfied in full
as of the date of this  Agreement,  and no  condition  exists  that  presents  a
material risk of NBT or any NBT ERISA Affiliate  incurring a material  liability
thereunder;

                        (vi) No NBT Plan is a "multiemployer plan," as such term
is  defined in Section  3(37) of ERISA,  nor has NBT or any NBT ERISA  Affiliate
ever had any  obligation  to  contribute  to a  multiemployer  plan or otherwise
incurred or assumed any liability for complete or partial withdrawal from such a
plan that is a pension plan subject to Title IV of ERISA.

                        (vii) All  contributions or other amounts payable by NBT
or any NBT ERISA  Affiliate  as of the  Effective  Time with respect to each NBT
Plan,  and all other  liabilities  of each such entity with  respect to such NBT
Plan, with respect to current or prior plan years,  have been paid or accrued in
accordance with GAAP and Section 412 of the Code;

                        (viii)  Neither NBT nor any NBT ERISA  Affiliate nor any
NBT Plan  has  engaged  in any  transaction  with  respect  to which  any of the
aforementioned  entities  could be subject to either a civil  liability or civil
penalty  assessed  pursuant to Section  409,  501(i) or 502(1) of ERISA or a tax
imposed pursuant to Section 4975 or 4976 of the Code;

                        (ix) There are,  and for the past three years there have
been, no inquiries,  proceedings,  claims, suits pending or, to the knowledge of
NBT,  threatened  (other than routine  claims for benefits) by any  governmental
agency or authority or by any participant or beneficiary  against any of the NBT
Plans,  the assets of any of the trusts

                                       32

<PAGE>

under such Plans or the Plan sponsor or the Plan  administrator,  or against any
fiduciary of any of such NBT Plans with respect to the design or operation of an
NBT Plan;

                        (x)  Each  NBT  Plan  could  be  terminated  as  of  the
Effective Time without  material  liability to NBT or any NBT ERISA Affiliate in
excess  of the  amount  accrued  with  respect  to such  Plan  on the  financial
statements of NBT or such NBT ERISA Affiliate;

                        (xi) No NBT Plan,  either  individually or collectively,
provides  for any payments by NBT or any NBT ERISA  Affiliate  that would not be
deductible under Code Sections  162(a)(1),  162(m) or 404, or that would,  after
giving effect to the transactions contemplated by this Agreement,  constitute an
"excess  parachute  payment"  within the meaning of Code Section 280G, nor would
the transactions  contemplated by this Agreement  accelerate the time of payment
or vesting, or increase the amount of compensation due to any employee;

                        (xii) No "accumulated  funding deficiency" as defined in
Section  302(a)(2)  of ERISA or Section 412 of the Code,  whether or not waived,
and no "unfunded  current  liability" as determined  under Section 412(1) of the
Code exists with  respect to any NBT Plan subject to Section 412 of the Code and
Section 302 of ERISA, and there are no unsatisfied  liabilities to participants,
the  IRS,  the DOL or the PBGC as a result  of the  termination  of any NBT Plan
other  than any such  liabilities  that  have not  become  due or that are being
contested in good faith;

                        (xiii) No NBT Plan has experienced a "reportable  event"
(as such term is defined in Section  4043(b) of ERISA) that is not subject to an
administrative or statutory waiver from the reporting requirement;

                        (xiv) All reports and  information  required to be filed
with the DOL,  IRS and PBGC or with plan  participants  and their  beneficiaries
with respect to each NBT Plan have been filed, and all annual reports (including
Form 5500 series) of such Plans were  certified  without  qualification  by each
Plan's  accountants and actuaries.  Any annual reports which are not yet due but
are  required to be filed with respect to a plan year which ended on or prior to
the  Effective  Date and any annual  reports which are required to be filed with
respect to current plan years shall be filed on a timely basis.

                        (xv) Any bond  required  under ERISA with respect to any
NBT Plan has been  obtained and is in full force and effect and no funds held by
or under the control of NBT are plan assets of any NBT Plan.

                  SECTION 3.11.  Material Contracts.

                  Except  as set  forth in  Section  3.11 of the NBT  Disclosure
Schedule,  as of the date of this Agreement,  neither NBT nor any NBT Subsidiary
is a  party  to  or  bound  by  (a)  any  contract  or  commitment  for  capital
expenditures  in  excess of  $500,000  for any one  project,  (b)  contracts  or
commitments  for the purchase of materials or supplies or for the performance of
services over a period of more than 60 days from the date of this  Agreement and
calling for aggregate  future  payments of $1,000,000 or more during the term of
such contract or commitment, (c) any contract which is a "material contract" (as
such term is

                                       33

<PAGE>

defined in Item 601(b)(10) of Regulation S-K of the SEC) that has not been filed
or  incorporated  by reference in the NBT SEC  Reports,  (d) any contract  which
contains  non-compete or exclusivity  provisions or restrictions with respect to
any  business or  geographic  area or (e) any contract  which would  prohibit or
materially  delay  the  consummation  of the  Merger  or any  other  transaction
contemplated  by this  Agreement.  Each  contract,  arrangement,  commitment  or
understanding  of the type  described in this Section  3.11,  whether or not set
forth in Section 3.11 of NBT  Disclosure  Schedule,  is referred to herein as an
"NBT  Contract".  Neither NBT nor any NBT  Subsidiary  knows of, or has received
notice  of,  any  violation  of any NBT  Contract  by any of the  other  parties
thereto,  except for violations which,  individually or in the aggregate,  would
not result in a Material Adverse Effect on NBT and NBT Subsidiaries,  taken as a
whole.

                  SECTION 3.12.  Environmental Matters.

                        (a)  Each  of  NBT  and  the  NBT   Subsidiaries  is  in
compliance in all material  respects with all applicable  federal and state laws
and  regulations   relating  to  pollution  or  protection  of  the  environment
(including  without  limitation,  laws and  regulations  relating to  emissions,
discharges,   releases  and  threatened  releases  of  Hazardous  Materials,  or
otherwise relating to the manufacture, processing, distribution, use, treatment,
storage, disposal, transport or handling of Hazardous Materials.

                        (b)  There  is  no  suit,  claim,  action,   proceeding,
investigation or notice pending or, to the knowledge of NBT,  threatened (or, to
the  knowledge  of NBT,  past or present  actions or events  that could form the
basis of any such suit, claim, action, proceeding,  investigation or notice), in
which NBT or any NBT Subsidiary  has been or, with respect to threatened  suits,
claims,  actions,  proceedings,  investigations  or notices  may be,  named as a
defendant (i) for alleged material noncompliance (including by any predecessor),
with any environmental  law, rule or regulation or (ii) relating to any material
release or threatened  release into the  environment of any Hazardous  Material,
occurring  at or on a  site  owned,  leased  or  operated  by  NBT  or  any  NBT
Subsidiary,  or to the  knowledge  of NBT  relating to any  material  release or
threatened release into the environment of any Hazardous Material,  occurring at
or on a site not owned, leased or operated by NBT or any NBT Subsidiary.

                        (c) During  the period of NBT's or any NBT  Subsidiary's
ownership or operation of any of its  properties,  there has not been,  to NBT's
knowledge,  any  material  release  of  Hazardous  Materials  in,  on,  under or
affecting any such property.

                        (d) To the  knowledge  of NBT,  neither  NBT nor any NBT
Subsidiary has made or  participated in any loan to any person who is subject to
any suit,  claim,  action,  proceeding,  investigation  or  notice,  pending  or
threatened,  with respect to (i) any alleged  material  noncompliance  as to any
property securing such loan with any environmental  law, rule or regulation,  or
(ii) the release or the threatened release into the environment of any Hazardous
Material  at a site owned,  leased or  operated  by such person on any  property
securing such loan.

                                       34

<PAGE>

                  SECTION 3.13.  Taxes.

                        Each of NBT and the NBT  Subsidiaries has duly filed all
Tax Returns  required to be filed by it on or prior to the date hereof (all such
returns being accurate and complete in all material  respects) and has duly paid
or made provision on the financial  statements  referred to in Sections 3.07 and
5.15 hereof in accordance  with GAAP for the payment of all material Taxes which
have been incurred or are due or claimed to be due from it by Taxing Authorities
on or prior to the date  hereof  other  than  Taxes  (a)  which  (x) are not yet
delinquent  or (y) are being  contested  in good  faith and set forth in Section
3.13 of the NBT  Disclosure  Schedule  and  (b)  which  have  not  been  finally
determined.  All  liability  with  respect to the Tax Returns of NBT and the NBT
Subsidiaries has been satisfied for all years to and including 1998. The IRS has
not  notified  NBT of,  or  otherwise  asserted,  that  there  are any  material
deficiencies with respect to the federal income Tax Returns of NBT subsequent to
tax year 1995. There are no material  disputes  pending,  or claims asserted for
Taxes or  assessments  upon NBT or any NBT  Subsidiary,  nor has NBT nor any NBT
Subsidiary been requested to give any currently  effective waivers extending the
statutory  period of  limitation  applicable  to any federal or state income Tax
Return for any period. In addition,  Tax Returns which are accurate and complete
in all material respects have been filed by NBT and the NBT Subsidiaries for all
periods  for which  returns  were due with  respect to income  tax  withholding,
Social Security and unemployment taxes and the amounts shown on such Tax Returns
to be due and payable have been paid in full or adequate  provision  therefor in
accordance  with  GAAP  has been  included  by NBT in the  financial  statements
referred to in Sections  3.07 and 5.15 hereof.  All NBT Tax Returns  relating to
federal income taxes have been examined by the relevant Taxing  Authorities,  or
closed without audit by applicable statutes of limitations, and all deficiencies
proposed as a result of such  examinations  have been paid or  settled,  for all
periods before and including the taxable year ended 1995. Except as set forth in
Section 3.13 of the NBT Disclosure Schedule,  neither NBT nor any NBT Subsidiary
has  consented  to any waiver or extension  of any statute of  limitations  with
respect to any Tax.  Neither  NBT nor any NBT  Subsidiary  has made an  election
under  Section  341(f) of the Code.  NBT has  provided or made  available to BSB
complete and correct  copies of its Tax Returns and all material  correspondence
and documents, if any, relating directly or indirectly to taxes for each taxable
year or other relevant period as to which the applicable  statute of limitations
has not run on the date hereof. For this purpose, "correspondence and documents"
include,  without limitation,  amended Tax Returns, claims for refunds,  notices
from Taxing  Authorities  of  proposed  changes or  adjustments  to Taxes or Tax
Returns,  consents to assessment or collection of Taxes, acceptances of proposed
adjustments,  closing agreements, rulings and determination letters and requests
therefor,  and all other written  communications  to or from Taxing  Authorities
relating to any material Tax  liability of NBT or any NBT  Subsidiary.  NBT will
not be a "foreign  person" as that term is used in ss.  1.1445-2 of the Treasury
Regulations  promulgated  under the Code.  NBT Bank is not a "United States real
property holding  corporation" within meaning of ss. 897 of the Code and was not
a "United States real property holding  corporation" on any "determination date"
(as defined in ss.  1.897-2(c) of such  Regulations)  that  occurred  during any
relevant period.

                                       35

<PAGE>

                   SECTION 3.14.  Affiliates.

                  Each  director,  executive  officer and other person who is an
"affiliate" (for purposes of Rule 145 under the Securities Act, and for purposes
of qualifying the Merger for "pooling-of-interests" accounting treatment) of NBT
is  listed  at  Section  3.14 of the NBT  Disclosure  Schedule,  and  except  as
indicated  thereon,  each such person has delivered to BSB concurrently with the
execution of this  Agreement,  a stockholder  agreement in the form of Exhibit G
hereto (the "NBT Stockholder Agreement").

                  SECTION 3.15.  Derivative Instruments.

                  All Derivative  Instruments to which NBT or any NBT Subsidiary
is a party or to which any of their  properties  or assets may be  subject  were
entered into in the ordinary course of business and, to the knowledge of NBT, in
accordance with prudent banking practice and applicable rules, regulations,  and
policies  of the  regulatory  agencies  and with  counterparties  believed to be
financially  responsible at the time and, to knowledge of NBT, are legal, valid,
and binding  obligations  enforceable in accordance  with their terms (except as
may be limited by bankruptcy, insolvency, moratorium, reorganization, or similar
laws  affecting  the rights of  creditors  generally,  and the  availability  of
equitable remedies), and, to the knowledge of NBT, are in full force and effect.
NBT and each NBT Subsidiary  has duly performed in all material  respects all of
its obligations under any such Derivative  Instruments,  and to the knowledge of
NBT, there are no breaches, violations, or defaults or allegations or assertions
of such by any party  thereunder  except for any such breaches,  violations,  or
defaults or allegations or assertions  which would not,  individually  or in the
aggregate, have a Material Adverse Effect on NBT and the NBT Subsidiaries, taken
as a whole.

                  SECTION 3.16.  Regulatory Approvals.

                  NBT is not aware of any aspect of, or issues  relating to, its
or the  NBT  Subsidiaries'  operations  and  business  that  would  prevent  the
condition of Closing set forth in Section 6.01(c) from being satisfied.

                  SECTION 3.17.  Brokers.

                  Except as  contemplated by or referenced in the April 12, 2000
letter agreement between McConnell,  Budd & Downes, Inc. ("MBD") and NBT, a true
and  complete  copy of which NBT has  delivered  to BSB,  no  broker,  finder or
investment  banker  is  entitled  to any  brokerage,  finder's  or other  fee or
commission in connection  with the  transactions  contemplated by this Agreement
based upon arrangements made by or on behalf of NBT or any NBT Subsidiary.

                  SECTION 3.18.  Pooling of Interest and Tax Matters.

                  Neither  NBT  nor,  to  the  knowledge  of  NBT,  any  of  its
affiliates  (as defined in Section 2.14) has through the date of this  Agreement
taken or agreed to take any action that would  prevent NBT from  accounting  for
the business  combination  to be effected by the Merger and the Bank Merger as a
pooling of interests in  accordance  with GAAP or would  prevent the Merger from
qualifying  as a  reorganization  under Section  368(a) of the Code.  NBT has no
reason to believe  that the Merger will not qualify as a pooling of interests or
as a reorganization under Section 368(a) of the Code.

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<PAGE>

                  SECTION 3.19.  Votes Required.

                  The  requisite  affirmative  votes of holders of a majority of
the outstanding  shares of NBT Common Stock entitled to vote with respect to the
approval of this  Agreement  and the  issuance of NBT Common Stock in the Merger
pursuant  to  this  Agreement  and  the  amendments  to  NBT's   Certificate  of
Incorporation  to increase  the number of shares of NBT Common Stock that NBT is
authorized to issue and to provide a new name for the Surviving  Corporation are
the only  votes of the  holders  of any class or series of NBT's  capital  stock
required in connection with the Merger.

                  SECTION 3.20.  Fairness Opinion.

                  NBT has  received an opinion of MBD on or prior to the date of
this Agreement to the effect that, as of the date of such opinion,  the Exchange
Ratio is fair to the  stockholders  of NBT, from a financial point of view ("NBT
Fairness  Opinion")  and MBD has  consented to the inclusion of the NBT Fairness
Opinion in the Registration Statement.

                  SECTION 3.21 Rights Agreement.

                  The  Board of  Directors  of NBT has taken  such  action as is
necessary to render the NBT Rights Agreement  inapplicable to the Merger and the
other transactions contemplated by this Agreement.

                                   ARTICLE IV

                            COVENANTS OF BSB AND NBT

                  SECTION 4.01.  Affirmative Covenants.

                        (a) Each of BSB and NBT hereby covenants and agrees with
the other that prior to the Effective Time,  unless the prior written consent of
the other shall have been obtained and except as otherwise  contemplated herein,
BSB will,  and will cause each BSB  Subsidiary  to, and NBT will, and will cause
each NBT  Subsidiary  to,  conduct their  respective  businesses in the ordinary
course  of  business  in a manner  consistent  with  past  practice,  use  their
respective  reasonable best efforts to preserve intact their respective business
organizations, keep available the services of their respective current officers,
employees and  consultants  and to preserve their  respective  current  business
relationships.

                        (b)  Notwithstanding  that  BSB  believes  that  it  has
established  all reserves  and taken all  provisions  for  possible  loan losses
required by GAAP and applicable laws, rules and regulations, BSB recognizes that
NBT may have adopted  different loan,  accrual and reserve  policies  (including
loan  classifications  and levels of reserves for possible loan losses). In that
regard,  BSB shall  establish  such  additional  accruals and reserves as may be
necessary  to conform the  accounting  and credit  loss  reserve  practices  and
methods of BSB to those of NBT,  provided,  that no such action need be effected
until

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<PAGE>

the parties receive all necessary  governmental and  stockholder  approvals  and
consents to consummate the transactions contemplated hereby.

                  SECTION 4.02.  Negative Covenants.

                  Except  as set  forth in  Section  4.02 of the BSB  Disclosure
Schedule  or  the  NBT  Disclosure  Schedule,  as  applicable,   and  except  as
specifically  contemplated  by this  Agreement,  from the date of this Agreement
until the Effective  Time, each of BSB and NBT shall not do, and, in the case of
BSB, permit the BSB  Subsidiaries to do, and, in the case of NBT, permit the NBT
Subsidiaries  to do,  without  the  prior  written  consent  of NBT or  BSB,  as
applicable, any of the following:

                        (a) adjust,  split,  combine or  reclassify  any capital
stock, declare or pay any dividend on, or make any other distribution in respect
of, its outstanding shares of capital stock,  except for quarterly dividends or,
in the case of the periodic  stock  dividends of NBT,  annual  declarations  and
payments in accordance with past practice and in per share amounts not in excess
of historical per share dividend amounts; provided, however, that after the date
of this  Agreement,  each of NBT and BSB  shall  coordinate  with the  other the
declaration  of any cash dividends in respect of NBT Common Stock and BSB Common
Stock and the record  dates and payment  dates  relating  thereto,  it being the
intention of the parties  hereto that holders of NBT Common Stock and BSB Common
Stock  shall  not  receive  two  cash  dividends,  or fail to  receive  one cash
dividend,  for any  quarter  with  respect to their  shares of NBT Common  Stock
and/or BSB  Common  Stock and any  shares of NBT  Common  Stock any such  holder
receives in exchange therefor in the Merger;

                        (b) (i) redeem, purchase or otherwise acquire any shares
of its  capital  stock or any  securities  or  obligations  convertible  into or
exchangeable  for any shares of its capital  stock,  or any  options,  warrants,
conversion  or other  rights to acquire any shares of its  capital  stock or any
such   securities   or   obligations,   (ii)   effect  any   reorganization   or
recapitalization, (iii) purchase or otherwise acquire any assets or stock of any
corporation,  bank or other  business for  consideration  which in the aggregate
exceeds $10 million, except that such amount shall be $30 million in the case of
any such  transaction  as to which NBT gives BSB advance  written notice and the
opportunity to confer and that would not delay the  transaction  contemplated by
this Agreement,  or (iv) liquidate,  sell, dispose of or encumber any assets for
consideration  which in the  aggregate  exceeds  $25  million  (except  for bank
borrowings and operations in the ordinary course);

                        (c) issue,  deliver,  award, grant or sell, or authorize
or propose the issuance,  delivery,  award,  grant or sale of, any shares of any
class of its capital  stock  (including  shares held in treasury) or any rights,
warrants or options to acquire, any such shares;

                        (d) propose or adopt any  amendments to its  certificate
of incorporation or bylaws;

                        (e) change any of its methods of accounting in effect at
December  31,  1999,  or  change  any of its  methods  of  reporting  income  or
deductions   for  federal  income

                                       38

<PAGE>

tax purposes from those  employed in the  preparation  of the federal income tax
returns for the taxable year ending December 31, 1998, except as may be required
by law or GAAP;

                        (f)  other  than  in the  ordinary  course  of  business
consistent with past practice,  or by operation of law in connection with merger
transactions set forth in Section 4.02 of the NBT Disclosure Schedule, incur any
indebtedness for borrowed money (other than (x) short-term indebtedness incurred
to refinance  short-term  indebtedness or (y)  indebtedness  among its corporate
affiliates),  or assume,  guarantee,  endorse or otherwise  as an  accommodation
become  responsible for the obligations of any other individual,  corporation or
other entity;

                        (g) except for  transactions  in the ordinary  course of
business  consistent with past practice,  and except for agreements entered into
or terminated in connection with merger  transactions  set forth in Section 4.02
of the NBT  Disclosure  Schedule  (other  than any such  termination  by  mutual
agreement  of the  parties),  enter into or terminate  any material  contract or
agreement,  or  make  any  change  in any of its  material  leases  or  material
contracts,  other than renewals of such  contracts and leases  without  material
adverse changes of terms;

                        (h)  increase in any manner the  compensation  or fringe
benefits  of any of its  employees,  except as  required  by  existing  plans or
agreements  or pay any  pension or  retirement  allowance  not  required  by any
existing  plan or agreement to any such  employees or become a party to,  adopt,
terminate, amend or commit itself to any pension, retirement,  profit sharing or
welfare  benefit  plan or  agreement  or  employment  agreement  with or for the
benefit of any employee  other than,  in each case,  in the  ordinary  course of
business consistent with past practice,  or except as required by existing plans
or  agreements,  or accelerate the vesting of any deferred  compensation,  stock
options or other stock-based compensation;

                        (i)  settle any claim,  action or  proceeding  involving
money damages,  except in the ordinary  course of business  consistent with past
practices;

                        (j) take any  action  that  would  prevent or impede the
Merger from qualifying (i) for pooling of interests accounting treatment or (ii)
as a  reorganization  within the meaning of Section  368 of the Code:  provided,
however,  that nothing contained herein shall limit the ability of NBT or BSB to
exercise its rights under the BSB Stock Option Agreement or the NBT Stock Option
Agreement, respectively;

                        (k) take any action that is  intended or may  reasonably
be expected to result in any of its  representations and warranties set forth in
this  Agreement  being or becoming  untrue in any  material  respect at any time
prior to the Effective Time, or in any of the conditions to the Merger set forth
in Article VI not being  satisfied  or in a violation  of any  provision of this
Agreement, except, in each case, as may be required by applicable law;

                        (l) take any  action  or fail to take any  action  which
individually  or in the aggregate can be reasonably  expected to have a Material
Adverse Effect on, in the case of BSB, BSB and the BSB Subsidiaries,  taken as a
whole or, in the case of NBT, NBT and the NBT Subsidiaries, taken as a whole; or

                                       39

<PAGE>

                        (m)  agree  in  writing  or  otherwise  to do any of the
foregoing.

                                    ARTICLE V

                              ADDITIONAL AGREEMENTS

                  SECTION 5.01.  Registration Statement; Joint Proxy Statement.

                        (a) As promptly as  practicable  after the  execution of
this  Agreement,  (i) BSB and NBT shall prepare the Joint Proxy  Statement which
shall  constitute the joint proxy statement of BSB and NBT and the prospectus of
NBT  relating  to the  meetings  of BSB's and NBT's  stockholders  to be held to
consider  approval  and  adoption of this  Agreement  and,  with respect to NBT,
related  amendments  to its  Certificate  of  Incorporation,  and (ii) NBT shall
prepare and file with the SEC a  registration  statement  on Form S-4  (together
with any amendments thereto,  the "Registration  Statement") which shall include
the Joint Proxy Statement, with respect to the registration of the shares of NBT
Common Stock to be issued to the  stockholders  and option holders of BSB in the
Merger.  NBT and BSB shall  each use its  reasonable  best  efforts to cause the
Registration  Statement to become  effective as soon as reasonably  practicable.
BSB will furnish to NBT all information  concerning BSB and the BSB Subsidiaries
required to be set forth in the Registration  Statement and NBT will provide BSB
and its counsel the  opportunity to review such  information as set forth in the
Registration  Statement and Joint Proxy Statement.  NBT and BSB will each render
to the other its full cooperation in preparing,  filing,  prosecuting the filing
of, and amending the  Registration  Statement such that it comports at all times
with the  requirements of the Securities Act and the Securities  Exchange Act of
1934, as amended (the "Exchange Act").  Each of NBT and BSB will promptly advise
the other if at any time prior to the Effective Time any information provided by
it for  inclusion in the  Registration  Statement  or the Joint Proxy  Statement
appears to have been,  or shall have become,  incorrect or  incomplete  and will
furnish the information necessary to correct such misstatements or omissions. As
promptly  as  practicable  after the  Registration  Statement  shall have become
effective,  each of BSB and NBT  will  mail the  Joint  Proxy  Statement  to its
respective  stockholders.  NBT shall also take any action  required  to be taken
under any applicable blue sky laws in connection with the issuance of the shares
of NBT Common Stock to be issued as set forth in this  Agreement and BSB and the
BSB  Subsidiaries  shall  furnish  all  information   concerning  BSB,  the  BSB
Subsidiaries  and  the  holders  of  Shares  and  other  assistance  as NBT  may
reasonably request in connection with such action.

                        (b) (i) The Joint  Proxy  Statement  shall  include  the
recommendation  of the Board of Directors of BSB to the  stockholders  of BSB in
favor of approval and adoption of this Agreement;  provided,  however,  that, in
connection with recommending  approval of a Superior  Competing  Transaction (as
defined in Section  5.05),  the Board of Directors of BSB may, at any time prior
to such time as the  stockholders  of BSB shall have adopted and  approved  this
Agreement in accordance with Delaware Law,  withdraw,  modify or change any such
recommendation  to the extent that the Board of Directors of BSB  determines  in
good faith,  after  consultation  with and based upon the advice of  independent
legal  counsel,  that  the  failure  to  so  withdraw,   modify  or  change  its

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<PAGE>

recommendation would cause the Board of Directors of BSB to breach its fiduciary
duties to BSB's stockholders under applicable law and,  notwithstanding anything
to the contrary contained in this Agreement,  any such withdrawal,  modification
or change of  recommendation  shall not constitute a breach of this Agreement by
BSB.

                              (ii) The Joint Proxy  Statement  shall include the
recommendation  of the Board of Directors of NBT to the  stockholders  of NBT in
favor of approval and adoption of this  Agreement and the issuance of NBT Common
Stock  in the  Merger  pursuant  to the  Agreement  and the  amendment  of NBT's
Certificate  of  Incorporation  to  increase  the number of shares of NBT Common
Stock  that NBT is  authorized  to issue and to  provide  for a new name for the
Surviving Corporation;  provided, however, that, in connection with recommending
approval of a Superior Competing Transaction, the Board of Directors of NBT may,
at any time prior to such time as the stockholders of NBT shall have adopted and
approved this  Agreement in accordance  with Delaware Law withdraw,  modify,  or
change any such  recommendation to the extent that the Board of Directors of NBT
determines in good faith,  after  consultation with and based upon the advice of
independent legal counsel, that the failure to so withdraw, modify or change its
recommendation would cause the Board of Directors of NBT to breach its fiduciary
duties to NBT's stockholders under applicable law and,  notwithstanding anything
to the contrary contained in this Agreement,  any such withdrawal,  modification
or change of  recommendation  shall not constitute a breach of this Agreement by
NBT.

                        (c)  Notwithstanding  any  withdrawal,  modification  or
change in any  approval or  recommendation  of the Board of  Directors of BSB or
NBT,  as the case may be,  each of BSB and NBT  agree to hold  their  respective
Stockholders'  Meetings in accordance with the time period  specified in Section
5.02.

                        (d)  No  amendment  or  supplement  to the  Joint  Proxy
Statement or the  Registration  Statement will be made by NBT or BSB without the
approval  of the  other  party  (which  will  not be  unreasonably  withheld  or
delayed).  NBT and BSB each will  advise the other,  promptly  after it receives
notice thereof, of the time when the Registration Statement has become effective
or any  supplement or amendment has been filed,  the issuance of any stop order,
the  suspension  of the  qualification  of the  NBT  Common  Stock  issuable  in
connection  with the Merger for  offering  or sale in any  jurisdiction,  or any
request  by  the  SEC  for  amendment  of  the  Joint  Proxy  Statement  or  the
Registration Statement, or comments thereon and responses thereto or requests by
the SEC for additional information.

                        (e) NBT  shall as  promptly  as  reasonably  practicable
prepare and submit to the NASDAQ a listing  application  covering  the shares of
NBT Common  Stock  issuable  in the  Merger  and the shares of NBT Common  Stock
underlying the BSB options outstanding  immediately prior to the Effective Time,
and shall use its  reasonable  best  efforts to obtain,  prior to the  Effective
Time,  approval  for the listing of such NBT Common  Stock,  subject to official
notice  of  issuance  and BSB  shall  cooperate  with NBT with  respect  to such
listing.

                        (f) The information supplied by NBT for inclusion in the
Registration Statement or the Joint Proxy Statement (including  incorporation by
reference)

                                       41

<PAGE>

shall not, at (i) the time the  Registration  Statement  is declared  effective,
(ii) the time the Joint Proxy Statement (or any amendment  thereof or supplement
thereto), is first mailed to the stockholders of NBT and BSB, respectively,  and
(iii) the time of each of the  Stockholders'  Meetings,  and (iv) the  Effective
Time,  contain  any untrue  statement  of a  material  fact or omit to state any
material  fact  required to be stated  therein or necessary in order to make the
statements  therein not misleading.  If at any time prior to the Effective Time,
any  event  or  circumstance  relating  to NBT or any NBT  Subsidiary,  or their
respective  officers or directors,  should be discovered by NBT that pursuant to
the  Securities Act or the Exchange Act should be set forth in an amendment or a
supplement to the Registration Statement or the Joint Proxy Statement, NBT shall
promptly  inform BSB. All documents that NBT is responsible  for filing with the
SEC in connection with the  transactions  contemplated  herein will comply as to
form and substance in all material  aspects with the applicable  requirements of
the Securities Act and the rules and regulations  promulgated thereunder and the
Exchange Act and the rules and regulations promulgated thereunder.

                        (g) The information supplied by BSB for inclusion in the
Registration Statement or the Joint Proxy Statement (including  incorporation by
reference)  shall not, at (i) the time the  Registration  Statement  is declared
effective,  (ii) the time the Joint Proxy Statement (or any amendment thereof or
supplement  thereto),  is  first  mailed  to the  stockholders  of NBT and  BSB,
respectively, and (iii) the time of each of the Stockholders' Meetings, and (iv)
the Effective Time,  contain any untrue  statement of a material fact or omit to
state any material fact  required to be stated  therein or necessary in order to
make  the  statements  therein  not  misleading.  If at any  time  prior  to the
Effective Time, any event or circumstance relating to BSB or any BSB Subsidiary,
or their  respective  officers or  directors,  should be  discovered by BSB that
pursuant to the  Securities  Act or the  Exchange  Act should be set forth in an
amendment  or a  supplement  to the  Registration  Statement  or the Joint Proxy
Statement,  BSB shall promptly inform NBT. All documents that BSB is responsible
for filing with the SEC in connection with the transactions  contemplated herein
will  comply  as to  form  and  substance  in all  material  respects  with  the
applicable  requirements  of the  Securities  Act and the rules and  regulations
promulgated  thereunder  and the  Exchange  Act and the  rules  and  regulations
promulgated thereunder.

                  SECTION 5.02.  Meetings of Stockholders.

                        (a) Each of BSB and NBT shall call and hold a meeting of
its stockholders  (collectively,  the "Stockholders'  Meetings"), as promptly as
practicable for the purpose of voting upon the adoption of this  Agreement,  and
BSB and NBT shall hold the  Stockholders'  Meetings as soon as practicable after
the date on which the  Registration  Statement  becomes  effective  and will use
reasonable best efforts to hold the Stockholders' Meetings on the same day. Each
of BSB and NBT  shall  use its  reasonable  best  efforts  to  solicit  from its
stockholders proxies in favor of the adoption of this Agreement,  and shall take
all  other  action   necessary  or  advisable  to  secure  the  vote(s)  of  its
stockholders  required by the Delaware Law in each case as  applicable to obtain
such approvals;  provided, however, that BSB or NBT, as applicable, shall not be
obligated to solicit  proxies in favor of the adoption of this  Agreement at its
Stockholders'  Meeting to the extent that the Board of  Directors of BSB or NBT,
as applicable,  determines in good faith that such failure to solicit proxies is
required in order to comply with its fiduciary duties under

                                       42

<PAGE>

applicable  Law after  receiving  advice to such effect from  independent  legal
counsel (who may be such  party's  regularly  engaged  outside  legal  counsel);
provided further,  however, that notwithstanding anything to the contrary in the
foregoing,  each  of BSB  and  NBT  shall  hold  its  Stockholders'  Meeting  in
accordance with the time periods specified in the first sentence of this Section
5.02.

                  SECTION 5.03.  Access to Information; Confidentiality.

                        (a) From the date hereof to the  Effective  Time, to the
extent permitted by applicable Laws and contracts,  BSB will provide to NBT (and
its officers, directors,  employees,  accountants,  consultants,  legal counsel,
investment bankers,  advisors,  agents and other representatives,  collectively,
"Representatives")  access  to all  information  and  documents  which  NBT  may
reasonably  request  regarding the  business,  assets,  liabilities,  employees,
contracts and other aspects of BSB.

                        (b) From the date hereof to the  Effective  Time, to the
extent  permitted by applicable Law and  contracts,  NBT will provide to BSB and
its  Representatives  access  to all  information  and  documents  which BSB may
reasonably  request  regarding the  business,  assets,  liabilities,  employees,
contracts and other aspects of NBT.

                        (c) The Parties  shall comply with and shall cause their
respective  Representatives  to comply with,  all their  respective  obligations
under  the   Confidentiality   Agreements  entered  into  by  the  parties  (the
"Confidentiality Agreements"), it being understood that the Parties hereto shall
have the rights as beneficiaries under such agreements.

                        (d) No investigation pursuant to this Section 5.03 shall
affect any  representation  or warranty in this Agreement of any Party hereto or
any condition to the obligations of the parties hereto.

                  SECTION 5.04.  Appropriate Action; Consents; Filings.

                  BSB and NBT shall use all  reasonable  efforts to (i) take, or
cause to be taken,  all  appropriate  action,  and do, or cause to be done,  all
things  necessary,  proper or advisable  under  applicable law to consummate and
make effective the transactions  contemplated by this Agreement; (ii) obtain all
consents,  licenses,  permits,  waivers,  approvals,  authorizations  or  orders
required  under Law  (including,  without  limitation,  all foreign and domestic
(federal, state and local) governmental and regulatory rulings and approvals and
parties to  contracts)  in  connection  with the  authorization,  execution  and
delivery of this  Agreement  and the  consummation  by them of the  transactions
contemplated hereby and thereby, including,  without limitation, the Merger; and
(iii)  make all  necessary  filings,  and  thereafter  make any  other  required
submissions,  with respect to this  Agreement and the Merger  required under (A)
the  Securities  Act  and  the  Exchange  Act  and  the  rules  and  regulations
promulgated  thereunder,  and any other  applicable  federal or state securities
laws;  (B) any  applicable  federal or state  banking laws  (including,  without
limitation,  filing a notice with the FRB with respect to approval of the Merger
under  the BHCA  and the  applicable  regulations  promulgated  thereunder  or a
request for waiver of the  jurisdiction of the FRB under the BHCA);  and (C) any
other  applicable law  (including,  without  limitation,

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<PAGE>

any applicable  state  insurance  laws).  BSB and NBT shall  cooperate with each
other in  connection  with the making of all such filings,  including  providing
copies of all such documents to the  non-filing  party and its advisors prior to
filing.  BSB and NBT shall furnish all information  required for any application
or  other  filing  to be made  pursuant  to the  rules  and  regulations  of any
applicable law (including all  information  required to be included in the Joint
Proxy  Statement  and  the  Registration   Statement)  in  connection  with  the
transactions  contemplated  by this  Agreement.  In case at any time  after  the
Effective  Time any further  action is  necessary  or desirable to carry out the
purposes of this  Agreement,  the proper officers and directors of each party to
this  Agreement  shall use all  reasonable  efforts  to take all such  necessary
action. Anything in this Agreement notwithstanding, neither BSB nor NBT shall be
required by virtue of this  Agreement to comply with or agree to any  regulatory
order,  condition,  demand,  or request that seeks the  divestiture of deposits,
branches,  or loans whose divestiture would constitute a Material Adverse Effect
with respect to the Surviving Corporation.

                  SECTION 5.05.  No Solicitation of Transactions.

                        (a)  BSB  shall   immediately  cease  and  cause  to  be
terminated  any existing  discussions  or  negotiations  relating to a Competing
Proposal (as defined  below),  other than with  respect to the Merger,  with any
parties conducted  heretofore.  BSB will not,  directly or indirectly,  and will
instruct its Representatives not to, directly or indirectly,  initiate,  solicit
or encourage (including by way of furnishing information or assistance), or take
any other action to facilitate, any inquiries or the making of any proposal that
constitutes,  or reasonably may be expected to lead to, any Competing  Proposal,
or  enter  into  or  maintain  discussions  or  negotiate  with  any  person  in
furtherance of or relating to such inquiries or to obtain a Competing  Proposal,
or agree to or  endorse  any  Competing  Proposal,  or  authorize  or permit any
Representative  of BSB or any of its  subsidiaries to take any such action,  and
BSB shall use its reasonable  best efforts to cause the  Representatives  of BSB
and the BSB  Subsidiaries  not to take any such action,  and BSB shall  promptly
notify NBT if any such  inquiries  or proposals  are made  regarding a Competing
Proposal, and BSB shall keep NBT informed, on a current basis, of the status and
terms of any such proposals;  provided,  however, that prior to such time as the
stockholders of BSB shall have adopted and approved this Agreement in accordance
with Delaware  Law,  nothing  contained in this Section 5.05 shall  prohibit the
Board of  Directors  of BSB from (i), in  connection  with a Superior  Competing
Transaction  (as defined  below),  furnishing  information  to, or entering into
discussions or negotiations with, any person that makes an unsolicited bona fide
proposal to acquire BSB  pursuant to a merger,  consolidation,  share  exchange,
business  combination or other similar  transaction,  if, and only to the extent
that, (A) the Board of Directors of BSB, after  consultation with and based upon
the advice of  independent  legal  counsel,  determines  in good faith that such
action  is  required  for the  Board  of  Directors  of BSB to  comply  with its
fiduciary  duties  to  stockholders  imposed  by  Delaware  Law,  (B)  prior  to
furnishing  such  information  to, or entering into  discussions or negotiations
with, such person,  BSB provides  written notice to NBT to the effect that it is
furnishing  information to, or entering into  discussions or negotiations  with,
such person,  (C) prior to  furnishing  such  information  to such  person,  BSB
receives from such person an executed  confidentiality  agreement  with terms no
less favorable to BSB than those  contained in the  Confidentiality  Agreements,
and (D) BSB

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<PAGE>

keeps NBT informed,  on a current  basis,  of the status and details of any such
discussions or negotiations; or (ii) complying with Rule 14e-2 promulgated under
the Exchange Act.

                        (b)  NBT  shall   immediately  cease  and  cause  to  be
terminated  any existing  discussions  or  negotiations  relating to a Competing
Proposal,  other than with  respect to the Merger,  with any  parties  conducted
heretofore.  NBT  will  not,  directly  or  indirectly,  and will  instruct  its
Representatives not to, directly or indirectly,  initiate,  solicit or encourage
(including by way of furnishing  information or  assistance),  or take any other
action  to  facilitate,  any  inquiries  or  the  making  of any  proposal  that
constitutes,  or may  reasonably  may be  expected  to lead  to,  any  Competing
Proposal,  or enter into or maintain discussions or negotiate with any person in
furtherance of or relating to such inquiries or to obtain a Competing  Proposal,
or agree to or  endorse  any  Competing  Proposal,  or  authorize  or permit any
Representative  of NBT or any of its  subsidiaries to take any such action,  and
NBT shall use its reasonable  best efforts to cause the  Representatives  of NBT
and the NBT  Subsidiaries  not to take any such action,  and NBT shall  promptly
notify BSB if any such  inquiries  or proposals  are made  regarding a Competing
Proposal, and NBT shall keep BSB informed, on a current basis, of the status and
terms of any such proposals;  provided,  however, that prior to such time as the
stockholders of NBT shall have adopted and approved this Agreement in accordance
with Delaware  Law,  nothing  contained in this Section 5.05 shall  prohibit the
Board of  Directors  of NBT from (i) in  connection  with a  Superior  Competing
Transaction,   furnishing  information  to,  or  entering  into  discussions  or
negotiations  with, any person that makes an  unsolicited  bona fide proposal to
acquire  NBT  pursuant  to a merger,  consolidation,  share  exchange,  business
combination or other similar  transaction,  if, and only to the extent that, (A)
the Board of Directors of NBT, after consultation with and based upon the advice
of  independent  legal  counsel,  determines  in good faith that such  action is
required for the Board of Directors of NBT to comply with its  fiduciary  duties
to  stockholders   imposed  by  Delaware  Law,  (B)  prior  to  furnishing  such
information to, or entering into discussions or negotiations  with, such person,
NBT  provides  written  notice  to BSB  to  the  effect  that  it is  furnishing
information to, or entering into discussions or negotiations  with, such person,
(C) prior to furnishing such information to such person,  NBT receives from such
person an executed confidentiality agreement with terms no less favorable to NBT
than those contained in the  Confidentiality  Agreements,  and (D) NBT keeps BSB
informed,  on a current basis, of the status and details of any such discussions
or  negotiations;  or (ii)  complying  with  Rule  14e-2  promulgated  under the
Exchange Act.

                        (c) For purposes of this Agreement, "Competing Proposal"
shall mean any of the following involving BSB or any BSB Subsidiary,  on the one
hand, or NBT or any NBT Subsidiary,  on the other hand: any inquiry, proposal or
offer from any person relating to any direct or indirect acquisition or purchase
by such person of a business of BSB or NBT, as applicable,  that constitutes 15%
or more of the net revenues,  net income or assets of BSB or NBT, as applicable,
and its  subsidiaries,  taken as a whole,  or 15% or more of any class of equity
securities of BSB or NBT, as applicable, or any of its subsidiaries,  any tender
offer  or  exchange  offer  that  if  consummated  would  result  in any  person
beneficially owning 15% or more of any class of equity securities of BSB or NBT,
as applicable, or any of its subsidiaries,  any merger, consolidation,  business
combination,  recapitalization,  liquidation, dissolution or similar transaction
involving BSB or NBT, as applicable, or any of its subsidiaries,  other than the
transactions contemplated by this Agreement.

                                       45

<PAGE>

                        (d) For purposes of this Agreement  "Superior  Competing
Transaction"  shall  mean  any  of  the  following  involving  BSB  or  any  BSB
Subsidiary,  on the one hand, or NBT or any NBT  Subsidiary,  on the other hand:
any proposal made by a third party to acquire, directly or indirectly, including
pursuant to a tender offer,  exchange  offer,  merger,  consolidation,  business
combination, recapitalization,  liquidation, dissolution or similar transaction,
for  consideration  consisting of cash and/or  securities,  more than 50% of the
combined  voting power of the shares of BSB Common Stock or NBT Common Stock, as
applicable,  then outstanding or all or substantially  all the assets of BSB and
NBT, as  applicable,  and otherwise on terms which the Board of Directors of BSB
or NBT,  as  applicable,  determines  in its good faith  judgment  (based on the
opinion of KBW or MBD, as applicable, or another financial advisor of nationally
recognized  reputation) to be more favorable to its stockholders than the Merger
and for which financing,  to the extent required,  is then committed or which if
not  committed  is,  in the good  faith  judgment  of its  Board  of  Directors,
reasonably capable of being obtained by such third party.

                  SECTION 5.06.  Indemnification.

                        (a) From and after the Effective  Time through the sixth
anniversary  thereof,  or until the final  disposition  of such Claim (as herein
defined)  with  respect to any Claim  asserted  within the  period,  NBT and the
Surviving Corporation shall, jointly and severally,  indemnify,  defend and hold
harmless  the  present  and former  officers,  directors  and  employees  of BSB
determined  as of the Closing Date  (collectively,  the  "Indemnified  Parties")
against all losses, expenses,  claims, damages,  liabilities or amounts that are
paid in settlement  of (with the approval of NBT and the Surviving  Corporation,
which will not be  unreasonably  withheld),  or in connection  with,  any claim,
action, suit, proceeding or investigation (a "Claim"), based in whole or in part
on the fact that such person is or was such a director,  officer or employee and
arising out of actions or omissions  occurring at or prior to the Effective Time
(including the transactions contemplated by this Agreement), in each case to the
fullest extent  permitted under Delaware Law and the Federal  Deposit  Insurance
Act ("FDIA") and NBT's  Certificate of  Incorporation  and Bylaws (and shall pay
expenses in advance of the final disposition of any such action or proceeding to
each  Indemnified  Party to the fullest extent  permitted under Delaware Law and
the FDIA, upon receipt from the Indemnified  Party to whom expenses are advanced
of the  undertaking  to repay such  advances;  provided  that the person to whom
expenses are advanced  provides an  undertaking  to repay such expenses if it is
ultimately determined that such person is not entitled to indemnification).

                        (b)   Any    Indemnified    Party   wishing   to   claim
indemnification  under this Section 5.06, upon learning of any such Claim, shall
notify NBT and the Surviving  Corporation (although the failure so to notify NBT
and the  Surviving  Corporation  shall  not  relieve  either  thereof  from  any
liability  that NBT or the  Surviving  Corporation  may have under this  Section
5.06, except to the extent such failure  materially  prejudices such party). NBT
and the Surviving Corporation shall have the right to assume the defense thereof
and if such right is exercised  NBT and the Surviving  Corporation  shall not be
liable to such  Indemnified  Parties for any legal  expenses of other counsel or
any  other  expenses  subsequently  incurred  by  such  Indemnified  Parties  in
connection  with  the  defense  thereof,  except  that if NBT and the  Surviving
Corporation  elect not to assume such defense or there is a conflict of interest
between NBT and the  Surviving  Corporation  and the  Indemnified

                                       46

<PAGE>

Parties,  the Indemnified Parties may retain counsel  satisfactory to them, and,
in such case, NBT and the Surviving  Corporation  shall pay all reasonable  fees
and expenses of such counsel for the Indemnified  Parties promptly as statements
therefor  are  received;  provided,  however,  that  (i) NBT  and the  Surviving
Corporation  shall not, in connection  with any one such action or proceeding or
separate but  substantially  similar  actions or proceedings  arising out of the
same general  allegations,  be liable for the fees and expenses of more than one
separate firm of attorneys at any time for all Indemnified Parties except to the
extent that local  counsel,  in addition to such parties'  regular  counsel,  is
necessary  or desirable in order to  effectively  defend  against such action or
proceeding, (ii) NBT, the Surviving Corporation and the Indemnified Parties will
cooperate  in the  defense of any such  matter,  or (iii) NBT and the  Surviving
Corporation  shall not be liable for any settlement  effected  without its prior
written consent, which consent will not be unreasonably withheld or delayed, and
provided,  further, that the Surviving Corporation shall not have any obligation
hereunder to any Indemnified Party when and if a court of competent jurisdiction
shall ultimately  determine,  and such determination shall have become final and
not subject to further  appeal,  that the  indemnification  of such  Indemnified
Party in the manner  contemplated  hereby is prohibited  by  applicable  law. No
Indemnified  Party  shall  consent  to entry of any  judgment  or enter into any
settlement that does not include as an unconditional  term thereof the giving by
the claimant or plaintiff to such  Indemnified  Party of a release,  in form and
substance reasonably  satisfactory to such Indemnified Party, from all liability
in respect of such claim or litigation for which such Indemnified Party would be
entitled to indemnification hereunder.

                        (c) NBT shall  purchase  for the  benefit of the persons
serving as executive  officers and  directors  of BSB  immediately  prior to the
Effective Time,  directors' and officers' liability insurance coverage for three
years after the  Effective  Time,  under either BSB's policy in existence on the
date hereof, or under a policy of similar coverage and amounts  containing terms
and  conditions  which are  generally not less  advantageous  than BSB's current
policy, and in either case, with respect to acts or omissions occurring prior to
the Effective Time which were committed by such executive officers and directors
in their  capacity  as such  provided,  however,  that in no event  shall NBT be
required to expend  pursuant to this Section  5.06(c) more than the amount equal
to 150 % of the  current  annual  amount  expended by BSB to maintain or procure
insurance coverage pursuant hereto. In connection with the foregoing, BSB agrees
to provide such insurer or substitute insurer with such  representations as such
insurer  may  reasonably  request  with  respect to the  reporting  of any prior
claims.

                        (d) This  Section 5.06 is intended to be for the benefit
of, and shall be enforceable  by, the  Indemnified  Parties  referred to herein,
their  heirs and  personal  representatives  and shall be binding on NBT and the
Surviving Corporation and their respective successors and assigns.

                  SECTION 5.07.  Employee Benefits.

                        (a) If any employee of BSB, any BSB  Subsidiary,  NBT or
any NBT Subsidiary becomes a participant in any employee benefit plan, practice,
or  policy of the  Surviving  Corporation,  the  Resulting  Bank or any  related
entity, such employee shall be given credit under such plan, practice, or policy
for all service prior to the Effective Time

                                       47

<PAGE>

with BSB,  such BSB  Subsidiary,  NBT, or such NBT  Subsidiary  for  purposes of
eligibility  and vesting,  but not for benefit  accrual  purposes under any such
plan,  practice,  or policy in which such employee was not a participant  before
the Effective  Time (except  that,  if any such  employee  benefit plan which is
instituted  or assumed  ("Assumed DB Plan") by the  Surviving  Corporation,  the
Resulting  Bank or  related  entity  pursuant  to  Section  5.07(c) is a defined
benefit plan with a cash  balance  feature,  each such  employee  shall  receive
credit under such Assumed DB Plan for his service with his employer prior to the
Effective Time for benefit  accrual  purposes,  except that the benefit  accrual
under any predecessor  defined benefit plan in which such employee  participated
shall be taken into account  under the Assumed DB Plan),  for which such service
is  taken  into  account  or  recognized,   and,  if  necessary,  the  Surviving
Corporation,  the Resulting  Bank, or related entity as applicable,  shall cause
any and all pre-existing  condition  limitations and eligibility waiting periods
under group  health  plans to be waived with  respect to such  participants  and
their  eligible  dependents  (except to the extent such  pre-existing  condition
limitations  are no more  onerous  than  similar  limitations,  or such  waiting
periods do not extend any waiting period,  applicable to such employee under the
plans of BSB or any BSB  Subsidiary),  provided that there be no  duplication of
such benefits as are provided under any employee  benefit plans,  practices,  or
policies  of  BSB,  any  BSB  Subsidiary,  NBT or any NBT  Subsidiary  that  are
instituted or continued in effect following the Effective Time.

                        (b) Each employee of BSB, any BSB Subsidiary, NBT or any
NBT Subsidiary  (except any employee who is a party to an employment,  change of
control  or  other  agreement  providing  for  severance  with  BSB or  any  BSB
Subsidiary) who becomes an employee of the Surviving Corporation, Resulting Bank
or any related entity or who,  following the Effective Time, remains an employee
of BSB, any BSB  Subsidiary,  NBT or any NBT Subsidiary and is terminated by the
Surviving  Corporation,  the Resulting Bank or any related entity  subsequent to
December 31, 2000 shall be entitled to severance pay, if any, in accordance with
the Surviving Corporation's,  Resulting Bank's or related entity's new severance
plan developed and instituted  pursuant to Section 5.07(c) on or before December
31, 2000. Such employee's service with BSB, such BSB Subsidiary, NBT or such NBT
Subsidiary shall be treated as service with the Surviving Corporation, Resulting
Bank or related entity for purposes of determining  the amount of severance pay,
if any,  under the new severance  plan of the Surviving  Corporation,  Resulting
Bank or related entity.  If any employee is terminated  after the Effective Time
but prior to  January  1,  2001,  such  employee  shall be covered by his former
employer's severance policy.

                        (c) On or before  January  1,  2001,  the  Parties  will
review their  respective  Plans,  and develop and institute new plans  effective
January 1, 2001.  The overall  benefits  program so developed and instituted for
the Surviving Corporation, Resulting Bank and each related entity, to the extent
feasible,  shall be comparable to the previous  overall benefit programs of BSB,
BSB Bank,  NBT and NBT Bank.  In order to effect the  foregoing,  the  Surviving
Corporation,  Resulting Bank, and related entities, as applicable,  shall, on or
before  January 1, 2001,  adopt any new plan  documents,  or amend existing Plan
documents  (including the Assumed DB Plan referred to in Section  5.07(a) above)
and shall  file any form that may be  required  to comply  with the terms of the
resulting  Plans,  the Code and  ERISA.  In the event  that  employees  who were
employees of BSB or any BSB Subsidiary at the Effective Time become participants
in a defined  benefit plan of the  Surviving  Corporation,  Resulting  Bank or a
related entity that has a cash

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<PAGE>

balance feature,  the Surviving  Corporation  will use  commercially  reasonable
efforts to provide such  employees  with  substantially  similar  elections with
respect to  participation  in such plan as were  provided to similarly  situated
employees of NBT and NBT Bank with respect to such plan. Nothing in this Section
5.07(c)  shall be deemed to  require  any  duplication  of  benefits.  Moreover,
nothing in this  Agreement  shall limit the right and authority of the Surviving
Corporation,  the Resulting Bank or related entities after the Effective Time to
adopt, amend, modify or terminate any Plan.

                  SECTION 5.08.  Executive Agreements and Employee Severance.

                        (a) NBT and BSB agree to cause the Surviving Corporation
and  each  relevant  BSB  Subsidiary  or  NBT   Subsidiary  to  honor,   without
modification,  and perform  its  obligations  under,  the  contracts,  plans and
arrangements  listed in Section  5.08(a) of BSB Disclosure  Schedule and the NBT
Disclosure Schedule.

                        (b)  Following  the Merger,  it is the intent of NBT and
the Surviving  Corporation  that such entities will, and will cause any of their
respective  direct and indirect  subsidiaries  to, in connection  with reviewing
candidates for employment  positions,  give equal opportunity for such positions
to employees of NBT and any NBT  Subsidiaries  and  employees of BSB and any BSB
Subsidiaries.  In addition,  employees of BSB will be accorded equal priority in
the hiring process.

                  SECTION 5.09.  Notification of Certain Matters.

                  BSB shall give prompt notice to NBT, and NBT shall give prompt
notice  to BSB,  of (i) the  occurrence,  or  non-occurrence,  of any  event the
occurrence,   or  non-occurrence,   of  which  would  be  likely  to  cause  any
representation  or  warranty  contained  in  this  Agreement  to  be  untrue  or
inaccurate,  and (ii) any  failure of BSB or NBT,  as the case may be, to comply
with or satisfy any  covenant,  condition,  or agreement to be complied  with or
satisfied by it hereunder;  provided,  however,  that the delivery of any notice
pursuant to this Section  5.09 shall not limit or otherwise  affect the remedies
available hereunder to the Party receiving such notice.

                  SECTION 5.10.  Public Announcements.

                  NBT and BSB shall  consult with each other before  issuing any
press  release or  otherwise  making any public  statements  with respect to the
Merger  and  shall  not issue any such  press  release  or make any such  public
statement  prior to such  consultation  and with mutual consent of both parties,
except as may be required by law or any listing  agreement with the Nasdaq Stock
Market.

                  SECTION 5.11.  Expenses.

                  (a) All Expenses (as described  below) incurred by NBT and BSB
shall be borne by the Party which has incurred the same, except that the Parties
shall share equally in the cost of filing the  Registration  Statement  with the
SEC,  printing the Joint Proxy  Statement and all other  regulatory  filing fees
incurred  in  connection  with this  Agreement.  Except as set forth in the next
sentence, in the event that this Agreement is terminated by either NBT or BSB by
reason of a material breach pursuant to Sections 7.01(c)

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<PAGE>

or (d) hereof or by NBT or BSB pursuant to Sections 7.01(e) and (f) hereof,  the
other  Party  shall pay all  documented,  reasonable  costs and  expenses  up to
$350,000 incurred by the terminating Party in connection with this Agreement and
the  transactions  contemplated  hereby.  In the event  that this  Agreement  is
terminated by NBT or BSB under  Section  7.01(e) by reason of  stockholders  not
having  given  any  required  approval,  the Party not  receiving  the  required
approval shall pay all documented,  reasonable costs and expenses up to $350,000
incurred  by  the  other  Party  in  connection  with  this  Agreement  and  the
transactions contemplated hereby. In the event that this Agreement is terminated
by NBT or BSB under  Section  7.01(g)  or (h) by  reason  of one of the  Parties
having  agreed to enter into an  Superior  Competing  Transaction  other than as
contemplated hereby, the Party entering into the Superior Competing  Transaction
shall pay all documented,  reasonable costs and expenses up to $350,000 incurred
by the other  Party in  connection  with  this  Agreement  and the  transactions
contemplated hereby.

                        (b) "Expenses" as used in this  Agreement  shall include
all reasonable out-of-pocket expenses (including,  without limitation,  all fees
and  expenses  of  counsel,   accountants,   investment  bankers,   experts  and
consultants  to the  Party  and its  affiliates)  incurred  by a Party or on its
behalf in  connection  with or related  to the  authorization,  preparation  and
execution of this Agreement, BSB Stock Option Agreement and the NBT Stock Option
Agreement,  the  solicitation  of  stockholder  approvals  and all other matters
related to the closing of the transactions contemplated hereby.

                  SECTION 5.12.  Delivery of Stockholder List.

                  BSB shall arrange to have its transfer agent deliver to NBT or
its designee, from time to time prior to the Effective Time, a true and complete
list setting forth the names and  addresses of the  stockholders  of BSB,  their
holdings of stock as of the latest  practicable date, and such other stockholder
information as NBT may reasonably request.

                  SECTION 5.13.  Letters of Accountants.

                        (a) BSB shall use its reasonable  efforts to cause to be
delivered  to  NBT a  "comfort"  letter  of  PricewaterhouseCoopers  LLP,  BSB's
independent  public  accountants,  dated and  delivered on the date on which the
Registration  Statement shall become  effective and as the date of the Effective
Time,  and  addressed  to NBT, in the form,  scope and content  contemplated  by
Statement  on Auditing  Standards  No. 72 issued by the  American  Institute  of
Certified  Public  Accountants,  Inc.  ("SAS  72"),  relating  to the  financial
statements  and other  financial  data with respect to BSB and its  consolidated
subsidiaries  included or incorporated by reference in the Joint Proxy Statement
and such other  matters as may be  reasonably  required  by NBT,  and based upon
procedures  carried out to a specified  date not earlier than five days prior to
the date thereof.

                        (b) NBT shall use its reasonable  efforts to cause to be
delivered  to BSB a  "comfort"  letter of KPMG  LLP,  NBT's  independent  public
accountants, dated and delivered on the date on which the Registration Statement
shall become  effective and as of the date of the Effective  Time, and addressed
to BSB, in the form,  scope and content  contemplated by SAS 72, relating to the
financial  statements  and  other  financial  data with  respect  to NBT and its
consolidated  subsidiaries included in or incorporated by reference in the Joint
Proxy Statement and such other matters as may be reasonably required by BSB,

                                       50

<PAGE>

and based upon  procedures carried out to a specified date not earlier than five
days prior to the date thereof.

                  SECTION 5.14.  BSB Reports.

                        (a) BSB shall timely file all required BSB Reports, each
of which (i) shall be prepared in all material  respects in accordance  with, in
the case of filings with the SEC, the requirements of the Securities Act and the
Exchange Act and the rules and  regulations of the SEC  promulgated  thereunder,
and in the case of all other BSB Reports,  the  requirements  of any  Regulatory
Agency  applicable  to such BSB  Reports and (ii) shall not at the time they are
filed  contain  any  untrue  statement  of a  material  fact or omit to  state a
material  fact  required to be stated  therein or necessary in order to make the
statements  therein,  in the light of the  circumstances  under  which they were
made, not misleading.

                        (b)  Each  of  the  consolidated   financial  statements
(including,  in each case, any notes thereto) contained in BSB SEC Reports filed
after  the date of this  Agreement  and  prior to the  Effective  Time  shall be
prepared in accordance  with the published  rules and regulations of the SEC and
GAAP  throughout  the periods  indicated and each shall present  fairly,  in all
material respects,  the consolidated  financial position,  results of operations
and cash flows of BSB and its consolidated  subsidiaries at the respective dates
thereof and for the respective  periods indicated therein (subject,  in the case
of unaudited statements,  to normal and recurring year-end adjustments which are
not  expected,  individually  or in the  aggregate,  to have a Material  Adverse
Effect upon BSB).

                  SECTION 5.15.  NBT Reports.

                        (a) NBT shall timely file all required NBT Reports, each
of which (i) shall be prepared in all material  respects in accordance  with, in
the case of filings with the SEC, the requirements of the Securities Act and the
Exchange Act and the rules and  regulations of the SEC  promulgated  thereunder,
and in the case of all other NBT Reports,  the  requirements  of any  Regulatory
Agency  applicable  to such NBT  Reports and (ii) shall not at the time they are
filed  contain  any  untrue  statement  of a  material  fact or omit to  state a
material  fact  required to be stated  therein or necessary in order to make the
statements  therein,  in the light of the  circumstances  under  which they were
made, not misleading.

                        (b)  Each  of  the  consolidated   financial  statements
(including,  in each case, any notes  thereto)  contained in the NBT SEC Reports
filed after the date of this  Agreement and prior to the Effective Time shall be
prepared in accordance  with the published  rules and regulations of the SEC and
GAAP  throughout  the periods  indicated and each shall present  fairly,  in all
material respects,  the consolidated  financial position,  results of operations
and cash flows of NBT and its  consolidated  subsidiaries  as at the  respective
dates thereof and for the respective periods indicated therein (subject,  in the
case of unaudited statements, to normal and recurring year-end adjustments which
are not expected,  individually or in the aggregate,  to have a Material Adverse
Effect upon NBT).

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<PAGE>

                  SECTION 5.16.  Pooling.

                  NBT and BSB  shall  take  all  reasonable  actions  to  insure
pooling of interest treatment for the Merger.

                  SECTION 5.17   Disclosure Schedules.

                  NBT and BSB  shall  promptly  advise  the  other  party of any
change  or  event  that,  individually  or in the  aggregate,  has or  would  be
reasonably  likely to have a Material  Adverse Effect on NBT or BSB, as the case
may be,  or to  cause or  constitute  a  breach  of any of its  representations,
warranties or covenants contained herein. From time to time prior to the Closing
Date,  each party will  promptly  supplement  or amend its  disclosure  schedule
delivered in  connection  with the  execution  of this  Agreement to reflect any
matter  which,  if existing,  occurring or known at the date of this  Agreement,
would  have  been  required  to be set  forth or  described  in such  disclosure
schedule or which is necessary  to correct any  information  in such  disclosure
schedule which has been rendered  inaccurate thereby. No supplement or amendment
to such disclosure schedule shall have any effect for the purpose of determining
satisfaction  of the conditions  set forth in Articles II or III hereof,  as the
case may be,  or the  compliance  by NBT or BSB,  as the  case may be,  with the
respective covenants set forth in Article IV hereof.

                  SECTION 5.18 Regulatory Matters.

                  (a) As promptly as  practicable  following  the  execution and
delivery of this  Agreement,  if  applicable,  BSB and NBT will prepare and file
with the United States  Federal Trade  Commission  (the "FTC") and the Antitrust
Division of the United States Department of Justice (the "DOJ") Notification and
Report Forms relating to the transactions contemplated herein if and as required
by the HSR Act, as well as comparable pre-merger  notification forms required by
the  merger  notification  or control  laws and  regulations  of any  applicable
jurisdiction,  as agreed by the parties (the "Antitrust  Filings").  The Parties
will  comply  with any  requests  for  additional  information  relating  to the
Antitrust  Filings  and will use their  reasonable  best  efforts  to secure all
required approvals of the Antitrust Filings.

                  (b) The Parties hereto shall cooperate with each other and use
their  reasonable  best  efforts  to  promptly  prepare  and file all  necessary
documentation, to effect all applications, notices, petitions and filings (which
shall include the Antitrust  Filings),  and to obtain as promptly as practicable
all permits,  consents,  approvals and  authorizations  of all third parties and
Governmental  Entities  which are  necessary  or  advisable  to  consummate  the
transactions  contemplated by this Agreement  (including  without limitation the
Merger).  BSB and NBT shall  have the right to  review  in  advance,  and to the
extent  practicable  each will  consult  the other on, in each case  subject  to
applicable  laws relating to the exchange of  information,  all the  information
relating  to BSB and NBT, as the case may be,  which  appears in any filing made
with, or written  materials  submitted  to, any third party or any  Governmental
Entity in connection  with the  transactions  contemplated by this Agreement and
will  promptly  notify  each other of any  communication  with any  Governmental
Entity and provide the other with an  opportunity to participate in any meetings
with a Governmental  Entity relating thereto;  provided,  however,  that nothing
contained  herein shall be deemed to provide either Party with a right to review
any information  provided to any Governmental  Entity on a confidential basis in
connection  with  the  transactions   contemplated  hereby.  In

                                       52

<PAGE>

exercising the foregoing right,  each of the Parties hereto shall act reasonably
and as promptly as practicable.  The Parties hereto agree that they will consult
with  each  other  with  respect  to the  obtaining  of all  permits,  consents,
approvals  and  authorizations  of all third parties and  Governmental  Entities
necessary or advisable  to  consummate  the  transactions  contemplated  by this
Agreement  and each Party will keep the other  apprised of the status of matters
relating to contemplation of the transactions contemplated herein.

                  (c)  BSB  and  NBT  shall  promptly  advise  each  other  upon
receiving  any  communication  from any  Governmental  Entity  whose  consent or
approval is required for consummation of the  transactions  contemplated by this
Agreement  which  causes  such  party to  believe  that  there  is a  reasonable
likelihood that any requisite  regulatory  approval will not be obtained or that
the receipt of any such approval will be materially delayed.

                                   ARTICLE VI

                              CONDITIONS OF MERGER

                  SECTION 6.01. Conditions to Obligation of Each Party to Effect
the Merger.

                  The respective  obligations of each Party to effect the Merger
shall be subject to the  satisfaction  at or prior to the Effective  Time of the
following conditions:

                        (a)  Effectiveness  of the Registration  Statement.  The
Registration  Statement shall have been declared  effective by the SEC under the
Securities Act. No stop order  suspending the  effectiveness of the Registration
Statement  shall have been issued by the SEC and no proceedings for that purpose
shall,  on or prior to the  Effective  Time,  have  been  initiated  or,  to the
knowledge  of NBT or BSB,  threatened  by the SEC.  NBT shall have  received all
other federal or state securities permits and other authorizations  necessary to
issue NBT Common Stock in exchange for BSB Common  Stock and to  consummate  the
Merger.

                        (b)  Stockholder  Approvals.  This Agreement  shall have
been approved and adopted by the requisite vote of the  stockholders of BSB. The
Agreement and the issuance of shares of NBT Common Stock in the Merger  pursuant
to this Agreement and the amendments to NBT's  Certificate of  Incorporation  to
increase  the number of shares of NBT Common  Stock  that NBT is  authorized  to
issue and to provide a new name for the  Surviving  Corporation  shall have been
approved by the requisite vote of the stockholders of NBT.

                        (c)  Regulatory  Approvals.  All requisite  approvals of
this Agreement and the transactions contemplated hereby shall have been received
from the FRB and any other applicable regulatory  authority,  and all conditions
required to be  satisfied  prior to the  Effective  Time imposed by the terms of
such  approvals  shall have been satisfied and all waiting  periods  relating to
such approvals shall have expired.

                        (d) Nasdaq Listing.  The shares of NBT Common Stock that
are to be issued to the  stockholders  of BSB and  holders of BSB options in the
Merger  shall have

                                       53

<PAGE>

been  authorized  for  listing on the Nasdaq  Stock  Market's  National  Market,
subject to notice of issuance.

                        (e) No  Order.  No  federal  or  state  governmental  or
regulatory authority or other agency or commission, or federal or state court of
competent jurisdiction,  shall have enacted,  issued,  promulgated,  enforced or
entered any statute,  rule, regulation,  executive order, decree,  injunction or
other order (whether  temporary,  preliminary  or permanent)  which is in effect
restricting,   preventing  or  prohibiting   consummation  of  the  transactions
contemplated by this Agreement.

                        (f) No Challenge. There shall not be pending any action,
proceeding or investigation before any court or administrative  agency or by any
government  agency or any other  person  (i)  challenging  or  seeking  material
damages in connection  with the Merger or (ii) seeking to restrain,  prohibit or
limit the  exercise of full rights of  ownership  or operation by NBT or the NBT
Subsidiaries  of all or any portion of the  business or assets of BSB or any BSB
Subsidiary,  which in either case has or would have a Material Adverse Effect on
NBT and the Surviving Corporation taken as a whole.

                        (g) Pooling Opinions. NBT and BSB shall have received an
opinion  from  KPMG LLP and  PriceWaterhouseCoopers  LLP,  respectively,  to the
effect that the Merger qualifies for pooling of interests  accounting  treatment
if consummated in accordance with this Agreement.

                        (h) NBT Tax Opinion.  NBT and BSB shall have received an
opinion of Duane,  Morris &  Heckscher  LLP,  special  counsel for NBT dated the
Closing Date (as defined in Section 8.01),  based upon  appropriate  assumptions
and qualifications,  to the effect that the Merger and the Bank Merger will each
be  treated   under   existing  law  for  federal   income  tax  purposes  as  a
reorganization  within the meaning of Section  368(a) of the Code,  and that NBT
and BSB will  each be a party  to that  reorganization  within  the  meaning  of
Section  368(b) of the Code that  shall have been  delivered  and that shall not
have been withdrawn or modified. In such opinion,  special counsel for NBT shall
be  entitled  to rely  upon  representations  of NBT,  BSB and any  other  party
reasonably satisfactory in form and substance to such counsel.

                  SECTION 6.02.  Additional Conditions to Obligations of NBT.

                  The  obligation of NBT to effect the Merger is also subject to
the following conditions:

                        (a)   Representation   and   Warranties.   Each  of  the
representations  and warranties of BSB set forth in this Agreement shall be true
and  correct in all  material  respects as of the  Closing  Date  (except to the
extent such  representations and warranties speak only as of an earlier date, in
which case such  representations and warranties shall be true and correct in all
material  respects  as of such  date) as  though  made as of the  Closing  Date;
provided, however, that for purposes of this paragraph, such representations and
warranties shall be deemed true and correct in all material  respects unless the
failure or failures of such  representations  and  warranties  to be so true and
correct,  individually or in the aggregate, would have a Material Adverse Effect
on BSB. Such determination of aggregate Material Adverse Effect shall be made as
if  there  were  no  materiality

                                       54

<PAGE>


qualifications in such representations and warranties. NBT shall have received a
certificate of the Chief Executive Officer of BSB dated the Closing Date to that
effect.

                        (b) Agreements  and Covenants.  BSB shall have performed
or  complied  in all  material  respects  with all  obligations  required  to be
performed by it under this  Agreement  on or prior to the  Effective  Time.  NBT
shall have received a certificate  of the Chief  Executive  Officer of BSB dated
the Closing Date to that effect.

                        (c) Consents Obtained. All consents, waivers, approvals,
authorizations or orders required to be obtained, and all filings required to be
made by BSB for the authorization,  execution and delivery of this Agreement and
the consummation by it of the transactions  contemplated  hereby shall have been
obtained  and made by BSB,  except  when the failure to obtain or make the same,
individually  or in the aggregate,  would not have a Material  Adverse Effect on
BSB and BSB Subsidiaries, taken as a whole, or the NBT and the NBT Subsidiaries,
taken as a whole.

                        (d)  Reserves  and  Accruals.  The reserves and accruals
described in Section 4.01(b) shall have been established.

                  SECTION 6.03.  Additional Conditions to Obligations of BSB.

                  The  obligation of BSB to effect the Merger is also subject to
the following conditions:

                        (a)   Representations   and  Warranties.   Each  of  the
representations  and warranties of NBT set forth in this Agreement shall be true
and  correct in all  material  respects as of the  Closing  Date  (except to the
extent such  representation and warranties speak as of an earlier date, in which
case  such  representation  and  warranties  shall  be true and  correct  in all
material  respects  as of such  earlier  date) as though  made as of the Closing
Date;   provided,   however,   that  for  purposes  of  this   paragraph,   such
representations  and warranties shall be deemed true and correct in all material
respects unless the failure or failures of such  representations  and warranties
to be so true  and  correct,  individually  or in the  aggregate,  would  have a
Material Adverse Effect on NBT. Such determination of aggregate Material Adverse
Effect  shall be made as if there  were no  materiality  qualifications  in such
representations  and  warranties.  BSB shall have received a certificate  of the
Chief Executive Officer of NBT dated the Closing Date to that effect.

                        (b) Agreements  and Covenants.  NBT shall have performed
or  complied  in all  material  respects  with all  obligations  required  to be
performed by it under this  Agreement  on or prior to the  Effective  Time.  BSB
shall have received a certificate  of the Chief  Executive  Officer of NBT dated
the Closing Date to that effect.

                        (c) Consents Obtained. All consents, waivers, approvals,
authorizations or orders required to be obtained, and all filings required to be
made by NBT for the authorization,  execution and delivery of this Agreement and
the consummation by it of the transactions  contemplated  hereby shall have been
obtained  and made by NBT,  except  when the failure to obtain or make the same,
individually  or in the aggregate,  would not have a Material  Adverse Effect on
BSB and BSB Subsidiaries, taken as a whole, or the NBT and the NBT Subsidiaries,
taken as a whole.

                                       55

<PAGE>

                                   ARTICLE VII

                        TERMINATION, AMENDMENT AND WAIVER

                  SECTION 7.01.  Termination.

                  This  Agreement  may be  terminated  at any time  prior to the
Effective Time,  whether before or after approval by the stockholders of BSB and
NBT of the matters presented in connection with the Merger:

                        (a) by mutual  written  consent duly  authorized  by the
Boards of Directors of each of NBT and BSB;

                        (b) by  either  NBT or BSB if either  (i) the  Effective
Time shall not have occurred on or before November 30, 2000; provided,  however,
that the right to terminate this Agreement  under this Section 7.01(b) shall not
be available  to any Party whose  failure to fulfill any  obligation  under this
Agreement  has been the cause of, or resulted  in, the failure of the  Effective
Time to occur on or  before  such  date or (ii) any  injunction  preventing  the
consummation of the Merger shall have become final and nonappealable;

                        (c) by NBT,  if there has been a breach of any  material
representation,  warranty, covenant or agreement on the part of BSB set forth in
this Agreement,  or if any  representation  or warranty of BSB shall have become
untrue,  in either case such that the conditions set forth in Section 6.02(a) or
Section  6.02(b)  would not be satisfied  and such breach is not cured within 30
days after written notice thereof to BSB by NBT;

                        (d) by BSB,  if there has been a breach of any  material
representation,  warranty, covenant or agreement on the part of NBT set forth in
this Agreement,  or if any  representation  or warranty of NBT shall have become
untrue,  in either case such that the conditions set forth in Section 6.03(a) or
Section  6.03(b)  would not be satisfied  and such breach is not cured within 30
days after written notice thereof to NBT by BSB;

                        (e) by  either  NBT or BSB if (i) at a duly  called  and
held  stockholders'  meeting therefor,  this Agreement shall fail to receive the
requisite  vote for approval and  adoption by BSB's  stockholders,  or (ii) at a
duly called and held  stockholders'  meeting  therefor,  this  Agreement and the
issuance of shares of NBT Common Stock in connection with the Merger pursuant to
this  Agreement  shall fail to  receive  the  requisite  vote for  approval  and
adoption by NBT's stockholders;

                        (f) by either NBT or BSB,  if at a duly  called and held
stockholders'   meeting  therefor,   the  amendments  of  NBT's  Certificate  of
Incorporation  to increase  the number of shares of NBT Common Stock that NBT is
authorized to issue and to provide a new name for the Surviving  Corporation  in
connection  with the Merger pursuant to this Agreement shall fail to receive the
requisite vote for approval by NBT's stockholders;

                                       56

<PAGE>


                        (g) by  BSB,  if  (i)  the  Board  of  Directors  of BSB
authorizes BSB, subject to complying with the terms of this Agreement,  to enter
into a binding written  agreement  concerning a transaction  that  constitutes a
Superior  Competing  Transaction  and the BSB  notifies  NBT in writing  that it
intends to enter into such an agreement,  attaching the most current  version of
such agreement (or a description  of all material terms and conditions  thereof)
to such notice, (ii) NBT does not make, within three business days of receipt of
BSB's written  notification  of its intention to enter into a binding  agreement
for a Superior  Competing  Transaction,  an offer that the Board of Directors of
BSB determines, in good faith after consultation with its financial advisors, is
at least as  favorable  to the  stockholders  of BSB as the  Superior  Competing
Transaction,  it being understood that BSB shall not enter into any such binding
agreement  during such three day period and (iii) BSB prior to such  termination
pursuant to this Section 7.01(g) pays to NBT in immediately  available funds the
fees  required  to be paid  pursuant to Section  5.11.  BSB agrees to notify NBT
promptly if its intention to enter into a written  agreement  referred to in its
notification shall change at any time after giving such notification; or

                        (h) by  NBT,  if  (i)  the  Board  of  Directors  of NBT
authorizes NBT, subject to complying with the terms of this Agreement,  to enter
into a binding written  agreement  concerning a transaction  that  constitutes a
Superior  Competing  Transaction and NBT notifies BSB in writing that it intends
to enter into such an  agreement,  attaching  the most  current  version of such
agreement (or a description  of all material  terms and  conditions  thereof) to
such notice,  (ii) BSB does not make,  within three  business days of receipt of
NBT's written  notification  of its intention to enter into a binding  agreement
for a Superior  Competing  Transaction,  an offer that the Board of Directors of
NBT determines, in good faith after consultation with its financial advisors, is
at least as  favorable  to the  stockholders  of NBT as the  Superior  Competing
Transaction,  it being understood that NBT shall not enter into any such binding
agreement  during such three day period and (iii) NBT prior to such  termination
pursuant to this Section 7.01(h) pays to BSB in immediately  available funds the
fees  required  to be paid  pursuant to Section  5.11.  NBT agrees to notify BSB
promptly if its intention to enter into a written  agreement  referred to in its
notification shall change at any time after giving such notification.

                  SECTION 7.02.  Effect of Termination.

                  Except  as  provided  in  Section   8.02,   in  the  event  of
termination of this  Agreement  pursuant to Section 7.01,  this Agreement  shall
forthwith  become void,  there shall be no liability under this Agreement on the
part of NBT or BSB or any of their  respective  officers  or  directors  and all
rights  and  obligations  of  each  Party  hereto  shall  cease;  provided  that
notwithstanding  anything to the contrary in this Agreement,  none of NBT or BSB
shall be released  from any  liabilities  or damages  arising out of its willful
breach of any provision of this Agreement.

                  SECTION 7.03.  Amendment.

                  This  Agreement may be amended by the Parties hereto by action
taken by or on behalf of their respective  Boards of Directors at any time prior
to the Effective Time; provided, however, that, after approval of this Agreement
by the  stockholders  of BSB and NBT, no  amendment  may be made which would (i)
alter or change the amount or kind of


                                       57

<PAGE>

consideration  into  which  each  Share  shall  be  converted  pursuant  to this
Agreement upon consummation of the Merger,  (ii) alter or change any term of the
certificate of incorporation of the Surviving  Corporation to be effected by the
Merger or (iii) alter or change any of the terms or conditions of this Agreement
if such  alteration or change would  adversely  affect the holders of BSB Common
Stock or NBT  Common  Stock.  This  Agreement  may not be  amended  except by an
instrument in writing signed by the Parties hereto.

                  SECTION 7.04.  Waiver.

                  At any time prior to the Effective  Time, any Party hereto may
(a) extend the time for the  performance of any of the obligations or other acts
of the other Party hereto, (b) waive any inaccuracies in the representations and
warranties contained herein or in any document delivered pursuant hereto and (c)
waive compliance with any of the agreements or conditions  contained herein. Any
such extension or waiver shall be valid if set forth in an instrument in writing
signed by the Party or Parties to be bound thereby.

                                  ARTICLE VIII

                               GENERAL PROVISIONS

                  SECTION 8.01.  Closing.

                  Subject to the terms and  conditions  of this  Agreement,  the
closing  (the  "Closing")  of the Merger will take place at 10:00 a.m. on a date
and place specified by the Parties,  which shall be no later than three business
days after the  satisfaction or waiver (subject to applicable law) of the latest
to occur of the  conditions  set forth in Article VI unless  extended  by mutual
agreement of the Parties (the "Closing Date").

                  SECTION 8.02.  Non-Survival of Representations, Warranties and
                                 Agreements.

                  The   representations,   warranties  and  agreements  in  this
Agreement  shall terminate at the Effective Time or upon the termination of this
Agreement  pursuant  to Article  VII,  except that the  agreements  set forth in
Article I shall survive the Effective Time  indefinitely  and those set forth in
Sections  5.03(c),  5.06,  5.07,  5.08, 5.11, 7.02 and Article VIII hereof shall
survive termination indefinitely.

                  SECTION 8.03.  Notices.

                  All notices and other  communications  given or made  pursuant
hereto  shall be in writing  and shall be deemed to have been duly given or made
as of the date  delivered  or  mailed  if  delivered  personally  or  mailed  by
registered  or certified or overnight  mail  (postage  prepaid,  return  receipt
requested) to the Parties at the following  addresses (or such other address for
a Party as shall be specified by like changes of address) and shall be effective
upon receipt:

                                       58

<PAGE>

                  (a)   If to NBT:

                        NBT Bancorp Inc.
                        52 South Broad Street
                        Norwich, New York  13815
                        Attention:  Mr. Daryl R. Forsythe

                        With a copy (which shall not constitute notice) to:

                        Duane, Morris & Heckscher LLP
                        1667 K Street, N.W., Suite 700
                        Washington, D.C.  20006
                        Attention:  Brian D. Alprin, Esq.

                  (b)   If to BSB:

                        BSB Bancorp, Inc.
                        58-68 Exchange Street
                        Binghamton, NY  13902
                        Attention:  President and Chief Executive Officer

                  With a copy (which shall not constitute notice) to:

                        Hogan & Hartson, L.L.P.
                        555 13th Street, N.W.
                        Washington, D.C.  20004
                        Attention:  Stuart G. Stein, Esq.

                        SECTION 8.04.  Additional Definitions.

                  For purposes of this Agreement, the term:

                        (a) "beneficial owner" with respect to any Shares, means
a person who shall be deemed to be the beneficial owner of such Shares (i) which
such person or any of its affiliates or associates  beneficially owns,  directly
or indirectly, (ii) which person or any of its affiliates or associates (as such
term is defined in Rule 12b-2 of the Exchange Act) has,  directly or indirectly,
(A) the right to acquire  (whether  such  right is  exercisable  immediately  or
subject only to the passage of time), pursuant to any agreement,  arrangement or
understanding  or upon the exercise of  consideration  rights,  exchange rights,
warrants  or options,  or  otherwise,  or (B) the right to vote  pursuant to any
agreement,  arrangement or  understanding,  (iii) which are beneficially  owned,
directly or indirectly, by any other persons with whom such person or any of its
affiliates or associates has any agreement, arrangement or understanding for the
purpose of  acquiring,  holding,  voting or  disposing  of any  Shares,  or (iv)
pursuant  to  Section  13(d) of the  Exchange  Act and any rules or  regulations
promulgated thereunder;

                        (b)  "Business  Day"  means any day other  than a day on
which banks in New York are required or authorized to be closed;

                                       59

<PAGE>

                        (c) "control"  (including the terms  "controlled by" and
"under common control with") means the possession,  directly or indirectly or as
trustee  or  executor,  of the power to direct  or cause  the  direction  of the
management or policies of a person, whether through the ownership of stock or as
trustee or executor, by contract or credit arrangement or otherwise;

                        (d) "Material  Adverse Effect" means any adverse change,
effect,  circumstance,  event or condition that is or is reasonably likely to be
materially  adverse  to NBT or BSB,  as the case may be,  and  their  respective
subsidiaries  taken as a whole,  business,  results of  operations,  properties,
financial  condition,  individually or in the aggregate,  or the ability of such
Party to consummate the transactions contemplated by this Agreement, except that
a Material  Adverse  Effect shall not be deemed to have  occurred as a result of
any change, effect, circumstance,  event or condition resulting from (i) general
changes in  economic  conditions  or the  securities  markets in  general;  (ii)
general changes in the banking/financial institutions industry; (iii) the Merger
or the transactions  contemplated  thereby (except that the first $10 million of
reserves and accruals  described in Section  4.01(b) shall be excepted from this
definition of "Material Adverse Effect") or the announcement thereof; and (iv) a
change in the trading prices of either NBT's or BSB's equity securities  between
the date of the Agreement and the Effective Time of the Merger.

                        (e)   "person"   means   an   individual,   corporation,
partnership,  association,  trust, unincorporated organization,  other entity or
group (as defined in Section 13(d) of the Exchange Act).

                  SECTION 8.05.  Headings.

                  The headings  contained in this  Agreement  are for  reference
purposes only and shall not affect in any way the meaning or  interpretation  of
this Agreement.

                  SECTION 8.06.  Severability.

                  If any term or other  provision of this  Agreement is invalid,
illegal or incapable of being enforced by any rule of law or public policy,  all
other conditions and provisions of this Agreement shall  nevertheless  remain in
full  force  and  effect  so long as the  economic  or  legal  substance  of the
transactions  contemplated  hereby is not affected in any manner  adverse to any
Party.  Upon such  determination  that any term or other  provision  is invalid,
illegal or incapable of being  enforced,  the Parties hereto shall  negotiate in
good faith to modify this  Agreement so as to effect the original  intent of the
Parties  as  closely  as  possible  in an  acceptable  manner  to the  end  that
transactions contemplated hereby are fulfilled to the extent possible.

                  SECTION 8.07.  Entire Agreement.

                  This  Agreement,  together  with  the BSB  and NBT  Disclosure
Schedules  and the  Exhibits  hereto,  constitutes  the entire  agreement of the
Parties and supersedes all prior agreements and  undertakings,  both written and
oral,  between the Parties,  or any of them,  with respect to the subject matter
hereof and, except as otherwise  expressly  provided herein,  is not intended to
confer upon any other person any rights or remedies hereunder.

                                       60

<PAGE>

                  SECTION 8.08.  Assignment.

                  This  Agreement  shall not be assigned by  operation of law or
otherwise.

                  SECTION 8.09.  Parties in Interest.

                  This  Agreement  shall be binding upon and inure solely to the
benefit of each Party hereto, and nothing in this Agreement, express or implied,
is  intended  to or shall  confer  upon any other  person any right,  benefit or
remedy of any nature whatsoever under of by reason of this Agreement.

                  SECTION 8.10.  Governing Law.

                  This  Agreement   shall  be  governed  by,  and  construed  in
accordance with, the laws of the State of Delaware,  regardless of the laws that
might otherwise govern under applicable principles of conflicts of law.

                  SECTION 8.11.  Counterparts.

                  This  Agreement  may be executed in one or more  counterparts,
and by the different Parties hereto in separate counterparts, each of which when
executed shall be deemed to be an original but all of which taken together shall
constitute one and the same agreement.





                                       61

<PAGE>


                  IN WITNESS WHEREOF,  NBT and BSB have caused this Agreement to
be  executed as of the date first  written  above by their  respective  officers
thereunto duly authorized.

                              NBT BANCORP INC.

                              By:     /s/ Daryl R. Forsythe
                                      -------------------------------------
                              Name:   Daryl R. Forsythe
                              Title:  President and Chief Executive Officer

                              BSB BANCORP, INC.

                              By:     /s/ Thomas L. Thorn
                                      -------------------------------------
                              Name:   Thomas L. Thorn
                              Title:  Acting President and Chief Executive
                                      Officer


                                       62


<PAGE>

                                                                       Exhibit A
                               BANK PLAN OF MERGER



         This Bank Plan of Merger  (this  "Plan of  Merger") is made and entered
into  as of  the  ____  day of  __________,  2000  between  NBT  BANK,  NATIONAL
ASSOCIATION,  a national banking association located in Norwich,  New York ("NBT
Bank") and BSB Bank & Trust Company,  a New  York-chartered  commercial bank and
trust company located in Binghamton, New York ("BSB Bank").


                                   WITNESSETH


         WHEREAS,  NBT Bancorp  Inc., a Delaware  corporation  ("NBT"),  and BSB
Bancorp,  Inc., a Delaware corporation  ("BSB"),  have entered into an Agreement
and Plan of Merger, dated as of April ____, 2000 (the "Agreement");


         WHEREAS, NBT Bank is a wholly owned subsidiary of NBT and BSB Bank is a
wholly owned subsidiary of BSB;


         WHEREAS,  BSB will merge with and into NBT pursuant to the terms of the
Agreement, and immediately thereafter BSB Bank will merge with and into NBT Bank
pursuant to this Plan of Merger,  with NBT Bank surviving as the resulting bank;
and


         WHEREAS, NBT Bank has _______ shares of common stock outstanding, $1.00
par value per share, and BSB Bank has 1,000 shares of capital stock outstanding,
$1.00 par value per share.


         NOW,  THEREFORE,  in  consideration  of the  premises  and  the  mutual
covenants and  agreements  contained  herein and in the  Agreement,  the parties
hereto do mutually agree, intending to be legally bound, as follows:


                                    ARTICLE 1
                                   DEFINITIONS


         Except as otherwise  provided herein,  the capitalized  terms set forth
below shall have the following meanings:


         1.1 "BANK  MERGER"  shall mean the merger of BSB Bank with and into NBT
Bank as provided in Section 2.1 of this Plan of Merger.



<PAGE>

         1.2  "EFFECTIVE  TIME" shall mean the date and time at which the merger
contemplated by this Plan of Merger becomes effective as provided in Section 2.2
hereof.


         1.3 "MERGING BANKS" shall mean, collectively, BSB Bank and NBT Bank.


         1.4 "OCC" shall mean the Office of the Comptroller of the Currency.


         1.5  "RESULTING  BANK" shall refer to NBT Bank as the surviving bank in
the Bank Merger.


                                    ARTICLE 2
                            TERMS OF THE BANK MERGER


         2.1      THE BANK MERGER

                  (a)  Subject  to the  terms  and  conditions  set forth in the
Agreement,  and in  accordance  with the National  Bank Act and the Federal Bank
Merger Act and the  regulations of the OCC promulgated  thereunder,  and the New
York Banking Law and the  regulations  of the New York Banking Board and the New
York  Superintendent  of Banks,  at the Effective Time, BSB Bank shall be merged
with and into NBT Bank  pursuant to and upon the terms set forth in this Plan of
Merger. NBT Bank shall continue as the Resulting Bank in the Bank Merger and the
separate existence of BSB Bank shall cease.


                  (b) As a result of the Bank Merger,  (i) each share of capital
stock, par value $1.00 per share, of BSB Bank issued and outstanding immediately
prior to the  Effective  Time shall be  canceled,  and (ii) each share of common
stock, par value $1.00 per share, of NBT Bank issued and outstanding immediately
prior to the  Effective  Time  shall  remain  issued and  outstanding  and shall
constitute  the only  shares of common  stock of the  Surviving  Bank issued and
outstanding immediately after the Effective Time.


                  (c) On and after the  Effective  Time,  the Bank Merger  shall
have the  effects  set forth in  Section  215a(c) of the  National  Bank Act and
Section 602 of the New York Banking Law.


         2.2      EFFECTIVE TIME

                  The Bank Merger shall become effective (the "Effective  Time")
at ____ __.m. on __________, 2000.


         2.3      NAME OF THE RESULTING BANK

                  The name of the Resulting Bank shall be "___________________."




                                      -2-
<PAGE>

         2.4      ARTICLES OF ASSOCIATION

                  On and after the Effective  Time,  the Articles of Association
of NBT Bank shall be the Articles of Association of the Resulting  Bank,  unless
and until amended in accordance  with  applicable  law except that the corporate
title shall be changed in accordance with Section 2.3 of this Plan of Merger.


         2.5      BYLAWS

                  On and after the Effective  Time, the bylaws of NBT Bank shall
be the bylaws of the Resulting Bank, unless and until amended in accordance with
applicable  law except that the  corporate  title shall be changed in accordance
with Section 2.3 of this Plan of Merger.


         2.6      DIRECTORS AND OFFICERS

                  The  directors and  executive  officers of the Resulting  Bank
shall be as set forth in Annex 1 hereto.


         2.7      CORPORATE ACTION

                  This Plan of Merger and the  consummation of the  transactions
contemplated  hereby have been duly and validly adopted and approved by at least
a  majority  of the Board of  Directors  of NBT Bank and BSB Bank,  and the sole
shareholder of each of the Merging Banks.


         2.8      OFFICES OF THE RESULTING BANK

                  NBT Bank,  as the  Resulting  Bank,  shall  relocate  its main
office to  Binghamton,  New York,  and shall  establish  a branch  office at its
former main  office  location  and also shall  establish  as branch  offices the
principal office and branch offices of BSB Bank (except the facility, if any, of
BSB that  becomes the main office of the  Resulting  Bank).  The location of the
main  office and other  offices of the  Resulting  Bank shall be as set forth at
Annex 2 hereto.


                                    ARTICLE 3
                                  MISCELLANEOUS


         3.1      SUCCESSORS

                  This Plan of Merger shall be binding on the  successors of NBT
Bank and BSB Bank.




                                      -3-
<PAGE>

         3.2      COUNTERPARTS

                  This Plan of Merger may be executed in two counterparts,  each
of which shall be deemed an original,  but which taken together shall constitute
one and the same document.



                                             [SIGNATURE PAGE FOLLOWS]



                                      -4-
<PAGE>

                  IN WITNESS  WHEREOF,  each of the parties has caused this Plan
of  Merger  to be duly  executed  on its  behalf by an  officer  thereunto  duly
authorized, all as of the day and year first above written.


                                        NBT BANK, NATIONAL ASSOCIATION



ATTEST:


By:                                     By:
    -------------------------------         -----------------------------
    Name:                                    Name:  Daryl R. Forsythe
    Title:  Senior Vice President and        Title: Chairman and Chief Executive
                Corporate Secretary                 Officer















                                        BSB BANK & TRUST COMPANY



ATTEST:

By:                                     By:
    --------------------------------        ------------------------------
    Name:  Larry G. Denniston               Name:  Thomas L. Thorn
    Title: Executive Vice President         Title: Acting President and Chief
           and Secretary                    Executive Officer








                                      -5-
<PAGE>

                                     ANNEX 1

         DIRECTORS AND OFFICERS OF RESULTING BANK AFTER THE BANK MERGER




<PAGE>


                                     ANNEX 2

                 OFFICES OF RESULTING BANK AFTER THE BANK MERGER

                  At the Effective  Time of the Bank Merger,  NBT Bank will have
the following offices:

Location of Main Office
- -----------------------



Location of Branch Offices
- --------------------------

































                                      -7-

<PAGE>

                                                                       Exhibit B


                    BSB BANCORP, INC. STOCK OPTION AGREEMENT


                       THE TRANSFER OF THE OPTION GRANTED
              BY THIS AGREEMENT IS SUBJECT TO RESALE RESTRICTIONS.


                  This STOCK OPTION AGREEMENT,  dated as of April 19, 2000 (this
"Agreement"),  is entered into between BSB Bancorp, Inc., a Delaware corporation
("Issuer"), and NBT Bancorp Inc., a Delaware corporation ("Grantee").

                                   WITNESSETH:

                  WHEREAS, Grantee and Issuer have entered into an Agreement and
Plan of Merger,  dated as of even date with this Agreement  (the "Plan"),  which
was executed by the parties  thereto prior to the  execution of this  Agreement;
and

                  WHEREAS,  as a condition and inducement to Grantee's  entering
into the Plan and in consideration therefor,  Issuer has agreed to grant Grantee
the Option (as defined below).

                  NOW,  THEREFORE,  in  consideration  of the  foregoing and the
mutual  covenants and  agreements  set forth herein and in the Plan, the parties
hereto agree as follows:

         SECTION 1. Issuer hereby grants to Grantee an  irrevocable  option (the
"Option") to purchase, subject to the terms hereof, up to a number of fully paid
and  nonassessable  shares of common stock,  par value $0.01 per share of Issuer
("Issuer Common Stock") equal to 19.9% of the total of the number of outstanding
shares  of Issuer  Common  Stock as of the first  date that the  Option  becomes
exercisable,  at a price per share equal to $18.50 (the "Option  Price")  [Note:
The option price will be the closing  market price of Issuer  common stock as of
the close of business on the day before execution].

         SECTION 2. (a) Grantee may  exercise the Option,  in whole or part,  at
any time and from time to time  following the occurrence of a Purchase Event (as
defined below); provided,  however, that the Option shall terminate and be of no
further  force and effect  upon the  earliest to occur of the  following  events
(which are collectively referred to as an "Exercise Termination Event"):

                  (i) The time immediately prior to the Effective Time;

                  (ii) 12 months after the first occurrence of a Purchase Event;

                  (iii)12 months after the termination of the Plan following the
         occurrence of a Preliminary Purchase Event (as defined below);

                  (iv) upon the termination of the Plan, if no Purchase Event or
         Preliminary  Purchase Event has occurred prior to such termination,  by
         Issuer pursuant to Section  7.01(d) of the Plan, both parties  pursuant
         to Section  7.01(a) of the Plan, or by either party pursuant to Section
         7.01(b) of the Plan;




<PAGE>

                  (v) upon  termination of the Plan, by either party pursuant to
         Sections  7.01(e) or (f) of the Plan based on (A) the required votes of
         Grantee's  stockholders  not being  obtained  for any reason at the NBT
         Stockholders' Meeting (as defined in the Plan) or (B) the required vote
         of Issuer's  stockholders  not being received at the BSB  Stockholders'
         Meeting (as defined in the Plan),  if no Purchase  Event or Preliminary
         Purchase   Event  has  occurred   prior  to  the  meeting  of  Issuer's
         stockholders (or any adjournment or postponement  thereof) held to vote
         on the Plan; or

                  (vi) 12 months after the  termination  of the Plan, by Grantee
         pursuant to Section  7.01(c) thereof as a result of a breach by Issuer,
         or by Grantee or Issuer pursuant to Section 7.01(g) or (h) of the Plan.

                  (b) The term  "Preliminary  Purchase  Event" shall mean any of
the following  events or transactions  occurring on or after the date hereof and
prior to an Exercise Termination Event:

                  (i) Issuer without  having  received  Grantee's  prior written
         consent,  shall have  entered  into any letter of intent or  definitive
         agreement to engage in an  Acquisition  Transaction  (as defined below)
         with any person (as  defined  below)  other than  Grantee or any of its
         subsidiaries (each a "Grantee Subsidiary") or the Board of Directors of
         Issuer shall have  recommended  that the stockholders of Issuer approve
         or accept  any  Acquisition  Transaction  with any  Person (as the term
         "person" is defined in Sections  3(a)9 and 13(d)(3) of the Exchange Act
         and the rules and  regulations  thereunder)  other than  Grantee or any
         Grantee  Subsidiary.  For  purposes  of  this  Agreement,  "Acquisition
         Transaction"  shall mean (x) a merger,  consolidation or other business
         combination   involving  Issuer,   (y)  a  purchase,   lease  or  other
         acquisition of all or substantially all of the assets of Issuer,  (z) a
         purchase   or  other   acquisition   (including   by  way  of   merger,
         consolidation, share exchange or otherwise) of Beneficial Ownership (as
         the term  "beneficial  ownership" is defined in Regulation  13d-3(a) of
         the Exchange Act) of securities  representing 20% or more of the voting
         power of Issuer;  provided,  however,  that  "Acquisition  Transaction"
         shall not include a transaction  entered into after the  termination of
         the Plan in which the Issuer is the surviving  entity, if in connection
         with such transaction,  no person acquires Beneficial  Ownership of 20%
         or more of the total voting power of the Issuer to be outstanding after
         giving effect to such  transaction  and in which the  aggregate  voting
         power of Issuer  acquired  by all persons is less than 33% of the total
         voting power of Issuer;

                  (ii) Any Person (other than Grantee, any Grantee Subsidiary or
         any  current  affiliate  of  Issuer)  shall  have  acquired  Beneficial
         Ownership  of 20% or more of the  outstanding  shares of Issuer  Common
         Stock;

                  (iii)(a)  Any  Person  (other  than  Grantee  or  any  Grantee
         Subsidiary)  shall  have made a bona fide  proposal  to Issuer or, by a
         public  announcement  or written  communication  that is or becomes the
         subject of public disclosure, to Issuer's stockholders prior to the BSB
         Stockholders'   Meeting  to  engage  in  an   Acquisition   Transaction
         (including, without limitation, any situation in which any Person other
         than Grantee or any Grantee  Subsidiary  shall have  commenced (as such
         term is defined in Rule 14d-2  promulgated  under the  Exchange  Act of
         1934,  as  amended  (the  "Exchange   Act"),  or  shall  have  filed  a
         registration  statement  under the  Securities  Act of 1933, as amended
         (the  "Securities  Act"),  with  respect to a tender  offer or exchange
         offer to purchase  any shares of Issuer  Common  Stock such that,  upon
         consummation of such offer, such person would have Beneficial Ownership
         of 20% or more of the then  outstanding  shares of Issuer  Common Stock
         (such an offer  being  referred  to herein




                                      -2-
<PAGE>

         as a "Tender Offer" or an "Exchange  Offer",  respectively) and (b) the
         stockholders  of Issuer do not approve  the  Merger,  as defined in the
         Plan, at the BSB Stockholders' Meeting;

                      (iv) There  shall  exist a willful or  intentional  breach
         under the Plan by Issuer  and such  breach  would  entitle  Grantee  to
         terminate the Plan; or

                      (v)  The BSB  Stockholders'  Meeting  to be  held  for the
         purpose of voting on the Plan shall not have been held  pursuant to the
         Plan or shall have been canceled  prior to  termination of the Plan, or
         for any reason whatsoever Issuer's Board of Directors shall have failed
         to recommend,  or shall have  withdrawn or modified in a manner adverse
         to Grantee the  recommendation  of Issuer's  Board of  Directors,  that
         Issuer's  stockholders approve the Plan, or if Issuer or Issuer's Board
         of  Directors  fails to oppose any  proposal of the type  described  at
         Section  2(b)(iii)(a)  above by any Person  (other than  Grantee or any
         Grantee Subsidiary).

                  (c) The term "Purchase  Event" shall mean any of the following
events or  transactions  occurring  on or after the date  hereof and prior to an
Exercise Termination Event:

                  (i) The  acquisition  by any Person (other than Grantee or any
         Grantee  Subsidiary) of Beneficial  Ownership  (other than on behalf of
         the Issuer) of 20% or more of the then outstanding Issuer Common Stock;

                  (ii) The occurrence of a Preliminary  Purchase Event described
         in Section 2(b)(i); or

                  (iii)The  termination  of the  Plan  by  Grantee  pursuant  to
         Section 7.01(c) thereof as a result of a willful or intentional  breach
         by Issuer or by Grantee or Issuer pursuant to Section 7.01(g) or (h) of
         the Plan.

                  (d) Issuer  shall  notify  Grantee  promptly in writing of the
occurrence of any Preliminary  Purchase Event or Purchase Event known to Issuer;
provided,  however,  that the  giving of such  notice  by Issuer  shall not be a
condition to the right of Grantee to exercise the Option.

                  (e) In the event  that  Grantee is  entitled  to and wishes to
exercise  the  Option,  it shall send to Issuer a written  notice  (the  "Option
Notice," the date of which being  hereinafter  referred to as the "Notice Date")
specifying  (i) the  total  number of  shares  of  Issuer  Common  Stock it will
purchase  pursuant  to such  exercise  and (ii) the  time  (which  shall be on a
business day that is not less than three nor more than 10 business days from the
Notice  Date) on which the  closing  of such  purchase  shall  take  place  (the
"Closing  Date");  such  closing  to take place at the  principal  office of the
Issuer;  provided,  however,  that if prior  notification  to or approval of the
Board  of  Governors  of the  Federal  Reserve  System  ("FRB"),  Office  of the
Comptroller of the Currency  ("OCC"),  the Federal Trade Commission (the "FTC"),
the  Antitrust  Division  of the  Department  of  Justice  ("DOJ")  or any other
Governmental  Authority is required in connection  with such purchase  (each,  a
"Notification" or an "Approval," as the case may be), at Grantee's sole expense,
(a) Grantee shall promptly file the required  notice or application for approval
("Notice/Application"),    (b)   Grantee   shall   expeditiously   process   the
Notice/Application  and (c) for the  purpose of  determining  the  Closing  Date
pursuant  to clause  (ii) of this  sentence,  the period of time that  otherwise
would  run from the  Notice  Date  shall  instead  run from the  later of (x) in
connection with any  Notification,  the date on which any required  notification
periods have expired or been terminated and (y) in connection with any Approval,
the date on which such  approval  has been  obtained and any  requisite  waiting
period or periods shall have expired.  For purposes of Section 2(a) hereof,  any
exercise  of the  Option  shall be deemed to occur on the Notice  Date  relating
thereto.  Prior to the Closing Date,  Grantee shall have the right to revoke



                                      -3-
<PAGE>

its  exercise of the Option by written  notice to the Issuer given not less than
three business days prior to the Closing Date.

                  (f) At the closing referred to in Section 2(e) hereof, Grantee
shall pay to Issuer  the  aggregate  purchase  price for the number of shares of
Issuer  Common Stock  specified in the Option  Notice in  immediately  available
funds  by wire  transfer  to a bank  account  designated  by  Issuer;  provided,
however,  that  failure or refusal of Issuer to  designate  such a bank  account
shall not preclude Grantee from exercising the Option.

                  (g) At such  closing,  simultaneously  with  the  delivery  of
immediately  available  funds as provided in Section 2(f)  hereof,  Issuer shall
deliver to Grantee a  certificate  or  certificates  representing  the number of
shares of Issuer Common Stock  specified in the Option Notice and, if the Option
should be exercised in part only, a new Option  evidencing the rights of Grantee
thereof to purchase the balance of the shares of Issuer Common Stock purchasable
hereunder.

                  (h)  Certificates  for  Issuer  Common  Stock  delivered  at a
closing hereunder shall be endorsed with a restrictive  legend  substantially as
follows:

                           The  transfer  of  the  shares  represented  by  this
                  certificate  is subject to resale  restrictions  arising under
                  the Securities Act of 1933, as amended,  and applicable  state
                  securities  laws and to  certain  provisions  of an  agreement
                  between BSB Bancorp,  Inc.  and NBT Bancorp  Inc.  dated as of
                  April 19,  2000.  A copy of such  agreement  is on file at the
                  principal  office of NBT,  and will be  provided to the holder
                  hereof without charge upon receipt by NBT of a written request
                  therefor.

It is understood and agreed that:  (i) the reference to the resale  restrictions
of the  Securities  Act in the above  legend  shall be  removed by  delivery  of
substitute certificate(s) without such reference if Grantee shall have delivered
to  Issuer a copy of a letter  from the  staff of the  Securities  and  Exchange
Commission (the "SEC") or Governmental  Authority  responsible for administering
any  applicable  state  securities  laws or an opinion of  counsel,  in form and
substance  satisfactory to Issuer's  counsel,  to the effect that such legend is
not required for purposes of the Securities Act or applicable  state  securities
laws; (ii) the reference to the provisions of this Agreement in the above legend
shall be removed by delivery of substitute certificate(s) without such reference
if the shares have been sold or transferred in compliance with the provisions of
this Agreement and under circumstances that do not require the retention of such
reference;  and  (iii)  the  legend  shall be  removed  in its  entirety  if the
conditions in the preceding clauses (i) and (ii) are both satisfied. In addition
such certificates shall bear any other legend as may be required by law.

                  (i) Upon the giving by  Grantee to Issuer of an Option  Notice
and the tender of the applicable  purchase price in immediately  available funds
on the Closing  Date,  unless  prohibited by  applicable  law,  Grantee shall be
deemed to be the holder of record of the number of shares of Issuer Common Stock
specified in the Option Notice, notwithstanding that the stock transfer books of
Issuer  shall then be closed or that  certificates  representing  such shares of
Issuer  Common Stock shall not then  actually be  delivered  to Grantee.  Issuer
shall pay all expenses and other charges that may be payable in connection  with
the preparation,  issuance and delivery of stock certificates under this Section
2 in the name of Grantee.

         SECTION  3.  Issuer  agrees:  (i) that it shall at all times  until the
termination  of this  Agreement  have reserved for issuance upon the exercise of
the Option that number of authorized and reserved  shares of Issuer Common Stock
equal to the  maximum  number of shares of Issuer  Common  Stock at any time and
from time to time issuable  hereunder,  all of which shares will,  upon issuance
pursuant hereto, be duly authorized, validly issued, fully paid, non-assessable,
and delivered  free



                                      -4-
<PAGE>

and clear of all claims,  liens,  encumbrances  and security  interests  and not
subject to any  preemptive  rights;  (ii) that it will not, by  amendment of its
certificate of incorporation or through reorganization,  consolidation,  merger,
dissolution or sale of assets,  or by any other  voluntary act, avoid or seek to
avoid the observance or performance  of any of the  covenants,  stipulations  or
conditions to be observed or performed  hereunder by Issuer;  (iii)  promptly to
take all reasonable action as may from time to time be requested by Grantee,  at
Grantee's  expense  (including  (x) complying  with all premerger  notification,
reporting and waiting period requirements specified in 15 U.S.C. Section 18a and
regulations  promulgated  thereunder  and (y) in the event prior  approval of or
notice to the FRB, OCC, FTC, DOJ or any other Governmental Authority,  under the
Hart-Scott-Rodino  Antitrust  Improvements  Act of 1976,  as  amended,  the Bank
Holding  Company  Act,  the Change in Bank  Control Act or any other  applicable
federal  or state  law,  is  necessary  before  the  Option  may be  exercised),
cooperating with Grantee in preparing such applications or notices and providing
such information to each such Governmental  Authority as it may require in order
to permit  Grantee to  exercise  the Option and Issuer duly and  effectively  to
issue shares of Issuer Common Stock pursuant hereto; and (iv) to take all action
provided herein to protect the rights of Grantee against dilution.

         SECTION  4.  This  Agreement  (and  the  Option  granted   hereby)  are
exchangeable,  without expense, at the option of Grantee,  upon presentation and
surrender  of this  Agreement  at the  principal  office  of  Issuer,  for other
agreements providing for Options of different denominations entitling the holder
thereof to purchase, on the same terms and subject to the same conditions as are
set forth  herein,  in the  aggregate the same number of shares of Issuer Common
Stock purchasable  hereunder.  The terms "Agreement" and "Option" as used herein
include any  agreements  and related  options for which this  Agreement (and the
Option  granted  hereby) may be  exchanged.  Upon  receipt by Issuer of evidence
reasonably  satisfactory to it of the loss, theft,  destruction or mutilation of
this  Agreement,  and (in the case of loss,  theft or destruction) of reasonably
satisfactory  indemnification,  and  upon  surrender  and  cancellation  of this
Agreement, if mutilated, Issuer will execute and deliver a new Agreement of like
tenor and date.

         SECTION 5. The number of shares of Issuer Common Stock purchasable upon
the exercise of the Option shall be subject to  adjustment  from time to time as
follows:

                  (a) In the event of any change in the type or number of shares
of  Issuer  Common  Stock by  reason  of stock  dividends,  split-ups,  mergers,
recapitalizations,  combinations, subdivisions, conversions, exchanges of shares
or other issuances of additional  shares (other than pursuant to the exercise of
the Option),  the type and number of shares of Issuer  Common Stock  purchasable
upon exercise hereof shall be appropriately  adjusted and proper provision shall
be made so that, in the event that any additional  shares of Issuer Common Stock
are to be issued or otherwise become  outstanding as a result of any such change
(other than  pursuant to an  exercise  of the  Option),  the number of shares of
Issuer  Common  Stock that remain  subject to the Option  shall be  increased or
decreased  (as  applicable)  so that,  after such issuance and together with the
shares of Issuer Common Stock  previously  issued  pursuant to the prior partial
exercise of the Option (as adjusted on account of any of the  foregoing  changes
in the Issuer Common Stock),  such number of shares shall equal the sum of 19.9%
of the  total of the  number  of  shares  of  Issuer  Common  Stock  issued  and
outstanding on the date the Option first becomes exercisable.

                  (b)  Whenever  the  number of shares  of Issuer  Common  Stock
purchasable  upon exercise hereof is adjusted as provided in this Section 5, the
Option  Price shall be adjusted by  multiplying  the Option Price by a fraction,
the  numerator of which shall be equal to the number of shares of Issuer  Common
Stock  purchasable prior to the adjustment and the denominator of which shall be
equal to the  number  of shares of Issuer  Common  Stock  purchasable  after the
adjustment.



                                      -5-
<PAGE>

         SECTION  6. (a) Upon the  occurrence  of a Purchase  Event that  occurs
prior to an Exercise  Termination Event, Issuer shall, at the request of Grantee
(whether on its own behalf or on behalf of any  subsequent  holder of the Option
(or part thereof) or of any of the shares of Issuer Common Stock issued pursuant
hereto),  promptly prepare, file and keep current a shelf registration statement
with the SEC,  under the  Securities Act covering any shares issued and issuable
pursuant to the Option and shall use its  reasonable  best efforts to cause such
registration statement to become effective,  and to remain current and effective
for a period not in excess of 90 days from the day such  registration  statement
first becomes effective, in order to permit the sale or other disposition of any
shares of Issuer  Common  Stock  issued  upon total or partial  exercise  of the
Option ("Option Shares") in accordance with any plan of disposition requested by
Grantee.  Grantee shall have the right to demand two such  registrations,  which
demand right shall be  transferable  but in no event shall Issuer be required to
effect more than two  registrations in the aggregate  pursuant to this Option or
any  subdivision  hereof.  Grantee  shall  provide  all  information  reasonably
requested  by Issuer for  inclusion  in any  registration  statement to be filed
hereunder.  In  connection  with any such  registration  statement,  Issuer  and
Grantee shall provide each other with representations,  warranties,  indemnities
and other agreements customarily given in connection with such registration.  If
requested by Grantee in connection  with such  registration,  Issuer and Grantee
shall become a party to any underwriting  agreement relating to the sale of such
shares,  but  only  to  the  extent  of  obligating  themselves  in  respect  of
representations,   warranties,  indemnities  and  other  agreements  customarily
included in such  underwriting  agreements and reasonably  acceptable to Issuer.
Notwithstanding  the foregoing,  if Grantee revokes any exercise notice or fails
to exercise any Option with respect to any exercise  notice  pursuant to Section
2(e) hereof,  Issuer shall not be obligated to continue any registration process
with  respect to the sale of Option  Shares  issuable  upon the exercise of such
Option and Grantee shall not be deemed to have demanded  registration  of Option
Shares.  If Issuer  withdraws a registration  statement  which has been declared
effective at the request of Grantee,  or any subsequent holder, then such filing
shall be deemed an effective registration for all purposes hereunder. The Issuer
will not be required to file any such  registration  statement during any period
of time  (not to exceed  30 days in the case of  clauses  (A) or (C) below or 45
days in the case of clause (B) below)  when (A) the Issuer is in  possession  of
material   non-public   information  which  it  reasonably   believes  would  be
detrimental to be disclosed at such time and such  information  would have to be
disclosed if a registration statement were filed at that time; (B) the Issuer is
required under the Securities  Act and the rules and  regulations  thereunder to
include  audited  financial  statements  for any  period  in  such  registration
statement and such  financial  statements are not yet available for inclusion in
such registration  statement;  or (C) the Issuer reasonably determines that such
registration  would  interfere  with  any  financing,  acquisition  or  material
transaction  involving  the Issuer.  The  registration  rights set forth in this
Section 6 are subject to the  condition  that the Grantee or  subsequent  holder
shall  provide the Issuer with such  information  with  respect to the  holder's
securities,  the plan for distribution  thereof, and such other information with
respect to the holder  that is  required  under  applicable  securities  laws to
enable the Issuer to include in a  registration  statement  all  material  facts
required to be disclosed  with respect to a registration  thereunder,  including
the identity of the holder and the holder's  plan of  distribution.  The Grantee
shall not be able to exercise its  registration  rights hereunder if Grantee can
rely on Rule 144  promulgated  under the  Securities  Act to sell such number of
shares of Issuer Common Stock that the Grantee otherwise would seek to register.

                  (b)  Concurrently   with  the  preparation  and  filing  of  a
registration  statement  under  Section 6(a) hereof,  Issuer shall also make all
filings  required to comply with state  securities laws in such number of states
as Grantee may reasonably request;  provided,  that Issuer shall not be required
to  qualify  to do  business  in, or  consent  to  service  of  process  in, any
jurisdiction by reason of this provision.



                                      -6-
<PAGE>

         SECTION  7.  Notwithstanding  Sections 2 and 6 hereof,  if Grantee  has
given the notice  referred to in one or more of such  Sections,  the exercise of
the rights  specified in any such Section  shall be extended (a) if the exercise
of such rights requires obtaining  regulatory  approvals (including any required
waiting periods) to the extent necessary to obtain all regulatory  approvals for
the exercise of such rights,  and (b) to the extent necessary to avoid liability
under  Section 16(b) of the Exchange Act by reason of such  exercise;  provided,
that in no event  shall any  closing  date occur  more than 12 months  after the
related  notice date,  and, if the closing date shall not have  occurred  within
such period due to the failure to obtain any required  approval by the FRB, OCC,
FTC, DOJ or any other Governmental Authority despite the reasonable best efforts
of Grantee and Issuer to obtain such approvals, the exercise of the rights shall
be deemed to have been rescinded as of the related notice date. In the event (a)
Grantee  receives  official notice that an approval of the FRB, OCC, FTC, DOJ or
any other  Governmental  Authority  required  for the  purchase  and sale of the
Option  Shares  will not be issued  or  granted  or (b) a  closing  date has not
occurred  within 12 months  after the related  notice date due to the failure to
obtain any such  required  approval,  Grantee  shall be entitled to exercise the
Option in connection with the concurrent resale of the Option Shares pursuant to
a registration statement as provided in Section 6 hereof.

         SECTION 8. Issuer hereby represents and warrants to Grantee as follows:

                  (a) Issuer has the requisite  corporate power and authority to
execute  and  deliver  this  Agreement  and  to  consummate   the   transactions
contemplated  hereby.  The  execution  and  delivery of this  Agreement  and the
consummation of the transactions  contemplated hereby have been duly approved by
the Board of Directors of Issuer and no other corporate  proceedings on the part
of Issuer are  necessary  to  authorize  this  Agreement  or to  consummate  the
transactions  so  contemplated.  This  Agreement  has  been  duly  executed  and
delivered  by,  and  constitutes  a valid and  binding  obligation  of,  Issuer,
enforceable against Issuer in accordance with its terms, subject to any required
Governmental  Approval,  and except as enforceability  thereof may be limited by
applicable bankruptcy, insolvency, reorganization,  moratorium and other similar
laws  affecting  the  enforcement  of  creditors'  rights  generally and general
principles of equity.

                  (b)  Issuer  has  taken  all  necessary  corporate  action  to
authorize and reserve and to permit it to issue,  and at all times from the date
hereof through the  termination  of this Agreement in accordance  with its terms
will have reserved for issuance upon the exercise of the Option,  that number of
shares of Issuer  Common  Stock equal to the maximum  number of shares of Issuer
Common Stock at any time and from time to time issuable hereunder,  and all such
shares, upon issuance pursuant hereto, will be duly authorized,  validly issued,
fully paid, non-assessable,  and will be delivered free and clear of all claims,
liens,  encumbrances  and security  interests and not subject to any  preemptive
rights.

         SECTION  9. (a)  Neither  of the  parties  hereto may assign any of its
rights or delegate  any of its  obligations  under this  Agreement or the Option
created hereunder to any other Person without the express written consent of the
other  party,  except that  Grantee may assign this  Agreement to a wholly owned
subsidiary of Grantee and Grantee may assign its rights hereunder in whole or in
part after the occurrence of a Preliminary Purchase Event. The term "Grantee" as
used in this  Agreement  shall  also be deemed to refer to  Grantee's  permitted
assigns.

                  (b) Any  assignment  of rights  of  Grantee  to any  permitted
assignee of Grantee hereunder shall bear the restrictive legend at the beginning
thereof substantially as follows:

                  The transfer of the option  represented by this assignment and
         the related option agreement is subject to resale restrictions  arising
         under the  Securities  Act of 1933, as amended,  and  applicable  state
         securities laws and to certain  provisions of an agreement



                                      -7-
<PAGE>

         between BSB Bancorp,  Inc. and NBT Bancorp Inc.,  dated as of April 19,
         2000. A copy of such  agreement is on file at the  principal  office of
         NBT,  and will be  provided  to any  permitted  assignee  of the Option
         without charge upon receipt of a written request therefor.

         SECTION 10. Each of Grantee and Issuer will use its reasonable  efforts
to make  all  filings  with,  and to  obtain  consents  of,  all  third  parties
including,  if  applicable,  the  FRB,  OCC,  FTC,  DOJ and  other  Governmental
Authorities  necessary to the consummation of the  transactions  contemplated by
this Agreement.

         SECTION 11. The parties  hereto  acknowledge  that damages  would be an
inadequate remedy for a breach of this Agreement by either party hereto and that
the  obligations  of the parties  hereto  shall be  enforceable  by either party
hereto through injunctive or other equitable relief.  Both parties further agree
to waive any  requirement  for the securing or posting of any bond in connection
with the  obtaining  of any such  equitable  relief and that this  provision  is
without  prejudice to any other rights that the parties  hereto may have for any
failure to perform this Agreement.

         SECTION 12. If any term,  provision,  covenant or restriction contained
in this Agreement is held by a court or a federal or state regulatory  agency of
competent  jurisdiction to be invalid,  void or unenforceable,  the remainder of
the terms, provisions and covenants and restrictions contained in this Agreement
shall remain in full force and effect, and shall in no way be affected, impaired
or  invalidated.  If for any reason such court or regulatory  agency  determines
that  Grantee is not  permitted  to acquire  the full number of shares of Issuer
Common Stock provided in Section 1 hereof (as adjusted pursuant  hereto),  it is
the express intention of Issuer to allow Grantee to acquire or to require Issuer
to  repurchase  such lesser number of shares as may be  permissible  without any
amendment or modification hereof.

         SECTION  13.  All  notices,   requests,   claims,   demands  and  other
communications  hereunder shall be deemed to have been duly given when delivered
in the manner and at the  respective  addresses  of the parties set forth in the
Plan.

         SECTION 14. This  Agreement,  the rights and obligations of the parties
hereto,  and any claims or disputes  relating  thereto  shall be governed by and
construed  in  accordance  with  the  laws of the  State  of  Delaware  (but not
including the choice of law rules thereof).

         SECTION 15. This  Agreement  may be executed in  counterparts,  each of
which shall be deemed to be an original,  but all of which shall  constitute one
and the same  agreement  and shall be  effective  at the time of  execution  and
delivery.

         SECTION 16. Except as otherwise  expressly provided herein, each of the
parties  hereto shall bear and pay all costs and  expenses  incurred by it or on
its behalf in connection with the transactions contemplated hereunder.

         SECTION 17.  Except as otherwise  expressly  provided  herein or in the
Plan,  this  Agreement  contains the entire  agreement  between the parties with
respect to the  transactions  contemplated  hereunder and  supersedes  all prior
arrangements or understandings with respect thereof,  written or oral. The terms
and  conditions of this  Agreement  shall inure to the benefit of and be binding
upon the parties hereto and their respective  successors and permitted  assigns.
Nothing in this Agreement,  expressed or implied, is intended to confer upon any
party, other than the parties hereto, and their respective  successors except as
assigns, any rights, remedies,  obligations or liabilities under or by reason of
this Agreement, except as expressly provided herein.



                                      -8-
<PAGE>

         SECTION 18.  Capitalized  terms used in this  Agreement and not defined
herein but defined in the Plan shall have the meanings assigned therein.

         SECTION 19.  Nothing  contained  in this  Agreement  shall be deemed to
authorize  or require  Issuer or Grantee to breach any  provision of the Plan or
any provision of law applicable to the Grantee or Issuer.

         SECTION 20. In the event that any selection or  determination  is to be
made  by  Grantee  or a  subsequent  holder  hereunder  and at the  time of such
selection  or  determination  there is more than one  Grantee or  holders,  such
selection shall be made by a majority in interest of such Grantees or holders.

         SECTION  21. In the event of any  exercise  of the  option by  Grantee,
Issuer and such  Grantee  shall  execute  and deliver  all other  documents  and
instruments and take all other action that may be reasonably  necessary in order
to consummate the transactions provided for by such exercise.

         SECTION 22. Except to the extent Grantee exercises the Option,  Grantee
shall have no rights to vote or receive  dividends or have any other rights as a
shareholder with respect to shares of Issuer Common Stock covered hereby.

                                             [SIGNATURE PAGE FOLLOWS]


                                      -9-
<PAGE>


         IN  WITNESS  WHEREOF,  each  of the  parties  has  caused  this  Option
Agreement  to be  executed  and  delivered  on its  behalf  by their  respective
officers thereunto duly authorized, all as of the date first above written.

                                     BSB BANCORP, INC.


                                     By:  /s/ Thomas L. Thorn
                                          --------------------------------------
                                     Name:  Thomas L. Thorn
                                     Title: Acting President and Chief Executive
                                            Officer



                                     NBT BANCORP INC.


                                     By:  /s/ Daryl R. Forsythe
                                          --------------------------------------
                                     Name:  Daryl R. Forsythe
                                     Title: President and Chief Executive
                                            Officer


<PAGE>

                                                                       Exhibit C


                     NBT BANCORP INC. STOCK OPTION AGREEMENT


                       THE TRANSFER OF THE OPTION GRANTED
              BY THIS AGREEMENT IS SUBJECT TO RESALE RESTRICTIONS.


                  This STOCK OPTION AGREEMENT,  dated as of April 19, 2000 (this
"Agreement"),  is entered into between NBT Bancorp Inc., a Delaware  corporation
("Issuer"), and BSB Bancorp, Inc., a Delaware corporation ("Grantee").

                                   WITNESSETH:

                  WHEREAS, Grantee and Issuer have entered into an Agreement and
Plan of Merger,  dated as of even date with this Agreement  (the "Plan"),  which
was executed by the parties  thereto prior to the  execution of this  Agreement;
and

                  WHEREAS,  as a condition and inducement to Grantee's  entering
into the Plan and in consideration therefor,  Issuer has agreed to grant Grantee
the Option (as defined below).

                  NOW,  THEREFORE,  in  consideration  of the  foregoing and the
mutual  covenants and  agreements  set forth herein and in the Plan, the parties
hereto agree as follows:

         SECTION 1. Issuer hereby grants to Grantee an  irrevocable  option (the
"Option") to purchase, subject to the terms hereof, up to a number of fully paid
and  nonassessable  shares of common stock,  par value $0.01 per share of Issuer
("Issuer Common Stock") equal to 19.9% of the total of the number of outstanding
shares  of Issuer  Common  Stock as of the first  date that the  Option  becomes
exercisable,  at a price per share equal to $12.13 (the "Option  Price")  [Note:
The option price will be the closing  market price of Issuer  common stock as of
the close of business on the day before execution].

         SECTION 2. (a) Grantee may  exercise the Option,  in whole or part,  at
any time and from time to time  following the occurrence of a Purchase Event (as
defined below); provided,  however, that the Option shall terminate and be of no
further  force and effect  upon the  earliest to occur of the  following  events
(which are collectively referred to as an "Exercise Termination Event"):

                  (i) The time immediately prior to the Effective Time;

                  (ii) 12 months after the first occurrence of a Purchase Event;

                  (iii) 12 months after the  termination  of the Plan  following
         the occurrence of a Preliminary Purchase Event (as defined below);

                  (iv) upon the termination of the Plan, if no Purchase Event or
         Preliminary  Purchase Event has occurred prior to such termination,  by
         Issuer pursuant to Section  7.01(c) of the Plan, both parties  pursuant
         to Section  7.01(a) of the Plan, or by either party pursuant to Section
         7.01(b) of the Plan;



<PAGE>

                  (v) upon  termination of the Plan, by either party pursuant to
         Sections  7.01(e) or (f) of the Plan based on (A) the required  vote of
         Grantee's  stockholders  not being  obtained  for any reason at the BSB
         Stockholders' Meeting (as defined in the Plan) or (B) the required vote
         of Issuer's  stockholders  not being received at the NBT  Stockholders'
         Meeting (as defined in the Plan),  if no Purchase  Event or Preliminary
         Purchase   Event  has  occurred   prior  to  the  meeting  of  Issuer's
         stockholders (or any adjournment or postponement  thereof) held to vote
         on the Plan; or

                  (vi) 12 months after the  termination  of the Plan, by Grantee
         pursuant to Section  7.01(d) thereof as a result of a breach by Issuer,
         or by Grantee or Issuer pursuant to Section 7.01(g) or (h) of the Plan.

                  (b) The term  "Preliminary  Purchase  Event" shall mean any of
the following  events or transactions  occurring on or after the date hereof and
prior to an Exercise Termination Event:

                  (i) Issuer without  having  received  Grantee's  prior written
         consent,  shall have  entered  into any letter of intent or  definitive
         agreement to engage in an  Acquisition  Transaction  (as defined below)
         with any person (as  defined  below)  other than  Grantee or any of its
         subsidiaries (each a "Grantee Subsidiary") or the Board of Directors of
         Issuer shall have  recommended  that the stockholders of Issuer approve
         or accept  any  Acquisition  Transaction  with any  Person (as the term
         "person" is defined in Sections  3(a)9 and 13(d)(3) of the Exchange Act
         and the rules and  regulations  thereunder)  other than  Grantee or any
         Grantee  Subsidiary.  For  purposes  of  this  Agreement,  "Acquisition
         Transaction"  shall mean (x) a merger,  consolidation or other business
         combination   involving  Issuer,   (y)  a  purchase,   lease  or  other
         acquisition of all or substantially all of the assets of Issuer,  (z) a
         purchase   or  other   acquisition   (including   by  way  of   merger,
         consolidation, share exchange or otherwise) of Beneficial Ownership (as
         the term  "beneficial  ownership" is defined in Regulation  13d-3(a) of
         the Exchange Act) of securities  representing 20% or more of the voting
         power of Issuer;  provided,  however,  that  "Acquisition  Transaction"
         shall not include a transaction  entered into after the  termination of
         the Plan in which the Issuer is the surviving  entity, if in connection
         with such transaction,  no person acquires Beneficial  Ownership of 20%
         or more of the total voting power of the Issuer to be outstanding after
         giving effect to such  transaction  and in which the  aggregate  voting
         power of Issuer  acquired  by all persons is less than 33% of the total
         voting power of Issuer;

                  (ii) Any Person (other than Grantee, any Grantee Subsidiary or
         any  current  affiliate  of  Issuer)  shall  have  acquired  Beneficial
         Ownership  of 20% or more of the  outstanding  shares of Issuer  Common
         Stock;

                  (iii)  (a) Any  Person  (other  than  Grantee  or any  Grantee
         Subsidiary)  shall  have made a bona fide  proposal  to Issuer or, by a
         public  announcement  or written  communication  that is or becomes the
         subject of public disclosure, to Issuer's stockholders prior to the NBT
         Stockholders'   Meeting  to  engage  in  an   Acquisition   Transaction
         (including, without limitation, any situation in which any Person other
         than Grantee or any Grantee  Subsidiary  shall have  commenced (as such
         term is defined in Rule 14d-2  promulgated  under the  Exchange  Act of
         1934,  as  amended  (the  "Exchange   Act"),  or  shall  have  filed  a
         registration  statement  under the  Securities  Act of 1933, as amended
         (the  "Securities  Act"),  with  respect to a tender  offer or exchange
         offer to purchase  any shares of Issuer  Common  Stock such that,  upon
         consummation of such offer, such person would have Beneficial Ownership
         of 20% or more of the then  outstanding  shares of Issuer  Common Stock
         (such an offer  being  referred  to herein



                                      -2-
<PAGE>

         as a "Tender Offer" or an "Exchange  Offer",  respectively) and (b) the
         stockholders  of Issuer do not approve  the  Merger,  as defined in the
         Plan, at the NBT Stockholders' Meeting;

                  (iv) There shall exist a willful or  intentional  breach under
         the Plan by Issuer and such breach would  entitle  Grantee to terminate
         the Plan; or

                  (v) The NBT  Stockholders'  Meeting to be held for the purpose
         of voting on the Plan shall not have been held  pursuant to the Plan or
         shall have been canceled  prior to  termination of the Plan, or for any
         reason  whatsoever  Issuer's  Board of  Directors  shall have failed to
         recommend,  or shall have  withdrawn or modified in a manner adverse to
         Grantee  the  recommendation  of  Issuer's  Board  of  Directors,  that
         Issuer's  stockholders approve the Plan, or if Issuer or Issuer's Board
         of  Directors  fails to oppose any  proposal of the type  described  at
         Section  2(b)(iii)(a)  above by any Person  (other than  Grantee or any
         Grantee Subsidiary).

                  (c) The term "Purchase  Event" shall mean any of the following
events or  transactions  occurring  on or after the date  hereof and prior to an
Exercise Termination Event:

                  (i) The  acquisition  by any Person (other than Grantee or any
         Grantee  Subsidiary) of Beneficial  Ownership  (other than on behalf of
         the Issuer) of 20% or more of the then outstanding Issuer Common Stock;

                  (ii) The occurrence of a Preliminary  Purchase Event described
         in Section 2(b)(i); or

                  (iii)  The  termination  of the Plan by  Grantee  pursuant  to
         Section 7.01(d) thereof as a result of a willful or intentional  breach
         by Issuer or by Grantee or Issuer pursuant to Section 7.01(g) or (h) of
         the Plan.

                  (d) Issuer  shall  notify  Grantee  promptly in writing of the
occurrence of any Preliminary  Purchase Event or Purchase Event known to Issuer;
provided,  however,  that the  giving of such  notice  by Issuer  shall not be a
condition to the right of Grantee to exercise the Option.

                  (e) In the event  that  Grantee is  entitled  to and wishes to
exercise  the  Option,  it shall send to Issuer a written  notice  (the  "Option
Notice," the date of which being  hereinafter  referred to as the "Notice Date")
specifying  (i) the  total  number of  shares  of  Issuer  Common  Stock it will
purchase  pursuant  to such  exercise  and (ii) the  time  (which  shall be on a
business day that is not less than three nor more than 10 business days from the
Notice  Date) on which the  closing  of such  purchase  shall  take  place  (the
"Closing  Date");  such  closing  to take place at the  principal  office of the
Issuer;  provided,  however,  that if prior  notification  to or approval of the
Board  of  Governors  of the  Federal  Reserve  System  ("FRB"),  Office  of the
Comptroller of the Currency  ("OCC"),  the Federal Trade Commission (the "FTC"),
the  Antitrust  Division  of the  Department  of  Justice  ("DOJ")  or any other
Governmental  Authority is required in connection  with such purchase  (each,  a
"Notification" or an "Approval," as the case may be), at Grantee's sole expense,
(a) Grantee shall promptly file the required  notice or application for approval
("Notice/Application"),    (b)   Grantee   shall   expeditiously   process   the
Notice/Application  and (c) for the  purpose of  determining  the  Closing  Date
pursuant  to clause  (ii) of this  sentence,  the period of time that  otherwise
would  run from the  Notice  Date  shall  instead  run from the  later of (x) in
connection with any  Notification,  the date on which any required  notification
periods have expired or been terminated and (y) in connection with any Approval,
the date on which such  approval  has been  obtained and any  requisite  waiting
period or periods shall have expired.  For purposes of Section 2(a) hereof,  any
exercise  of the  Option  shall be deemed to occur on the Notice  Date  relating
thereto.  Prior to the Closing Date,  Grantee shall have the right to revoke


                                      -3-
<PAGE>

its  exercise of the Option by written  notice to the Issuer given not less than
three business days prior to the Closing Date.

                  (f) At the closing referred to in Section 2(e) hereof, Grantee
shall pay to Issuer  the  aggregate  purchase  price for the number of shares of
Issuer  Common Stock  specified in the Option  Notice in  immediately  available
funds  by wire  transfer  to a bank  account  designated  by  Issuer;  provided,
however,  that  failure or refusal of Issuer to  designate  such a bank  account
shall not preclude Grantee from exercising the Option.

                  (g) At such  closing,  simultaneously  with  the  delivery  of
immediately  available  funds as provided in Section 2(f)  hereof,  Issuer shall
deliver to Grantee a  certificate  or  certificates  representing  the number of
shares of Issuer Common Stock  specified in the Option Notice and, if the Option
should be exercised in part only, a new Option  evidencing the rights of Grantee
thereof to purchase the balance of the shares of Issuer Common Stock purchasable
hereunder.

                  (h)  Certificates  for  Issuer  Common  Stock  delivered  at a
closing hereunder shall be endorsed with a restrictive  legend  substantially as
follows:

                           The  transfer  of  the  shares  represented  by  this
                  certificate  is subject to resale  restrictions  arising under
                  the Securities Act of 1933, as amended,  and applicable  state
                  securities  laws and to  certain  provisions  of an  agreement
                  between NBT Bancorp  Inc. and BSB  Bancorp,  Inc.  dated as of
                  April 19,  2000.  A copy of such  agreement  is on file at the
                  principal  office of BSB,  and will be  provided to the holder
                  hereof without charge upon receipt by BSB of a written request
                  therefor.

It is understood and agreed that:  (i) the reference to the resale  restrictions
of the  Securities  Act in the above  legend  shall be  removed by  delivery  of
substitute certificate(s) without such reference if Grantee shall have delivered
to  Issuer a copy of a letter  from the  staff of the  Securities  and  Exchange
Commission (the "SEC") or Governmental  Authority  responsible for administering
any  applicable  state  securities  laws or an opinion of  counsel,  in form and
substance  satisfactory to Issuer's  counsel,  to the effect that such legend is
not required for purposes of the Securities Act or applicable  state  securities
laws; (ii) the reference to the provisions of this Agreement in the above legend
shall be removed by delivery of substitute certificate(s) without such reference
if the shares have been sold or transferred in compliance with the provisions of
this Agreement and under circumstances that do not require the retention of such
reference;  and  (iii)  the  legend  shall be  removed  in its  entirety  if the
conditions in the preceding clauses (i) and (ii) are both satisfied. In addition
such certificates shall bear any other legend as may be required by law.

                  (i) Upon the giving by  Grantee to Issuer of an Option  Notice
and the tender of the applicable  purchase price in immediately  available funds
on the Closing  Date,  unless  prohibited by  applicable  law,  Grantee shall be
deemed to be the holder of record of the number of shares of Issuer Common Stock
specified in the Option Notice, notwithstanding that the stock transfer books of
Issuer  shall then be closed or that  certificates  representing  such shares of
Issuer  Common Stock shall not then  actually be  delivered  to Grantee.  Issuer
shall pay all expenses and other charges that may be payable in connection  with
the preparation,  issuance and delivery of stock certificates under this Section
2 in the name of Grantee.

         SECTION  3.  Issuer  agrees:  (i) that it shall at all times  until the
termination  of this  Agreement  have reserved for issuance upon the exercise of
the Option that number of authorized and reserved  shares of Issuer Common Stock
equal to the  maximum  number of shares of Issuer  Common  Stock at any time and
from time to time issuable  hereunder,  all of which shares will,  upon issuance
pursuant hereto, be duly authorized, validly issued, fully paid, non-assessable,
and delivered  free



                                      -4-
<PAGE>

and clear of all claims,  liens,  encumbrances  and security  interests  and not
subject to any  preemptive  rights;  (ii) that it will not, by  amendment of its
certificate of incorporation or through reorganization,  consolidation,  merger,
dissolution or sale of assets,  or by any other  voluntary act, avoid or seek to
avoid the observance or performance  of any of the  covenants,  stipulations  or
conditions to be observed or performed  hereunder by Issuer;  (iii)  promptly to
take all reasonable action as may from time to time be requested by Grantee,  at
Grantee's  expense  (including  (x) complying  with all premerger  notification,
reporting and waiting period requirements specified in 15 U.S.C. Section 18a and
regulations  promulgated  thereunder  and (y) in the event prior  approval of or
notice to the FRB, OCC, FTC, DOJ or any other Governmental Authority,  under the
Hart-Scott-Rodino  Antitrust  Improvements  Act of 1976,  as  amended,  the Bank
Holding  Company  Act,  the Change in Bank  Control Act or any other  applicable
federal  or state  law,  is  necessary  before  the  Option  may be  exercised),
cooperating with Grantee in preparing such applications or notices and providing
such information to each such Governmental  Authority as it may require in order
to permit  Grantee to  exercise  the Option and Issuer duly and  effectively  to
issue shares of Issuer Common Stock pursuant hereto; and (iv) to take all action
provided herein to protect the rights of Grantee against dilution.

         SECTION  4.  This  Agreement  (and  the  Option  granted   hereby)  are
exchangeable,  without expense, at the option of Grantee,  upon presentation and
surrender  of this  Agreement  at the  principal  office  of  Issuer,  for other
agreements providing for Options of different denominations entitling the holder
thereof to purchase, on the same terms and subject to the same conditions as are
set forth  herein,  in the  aggregate the same number of shares of Issuer Common
Stock purchasable  hereunder.  The terms "Agreement" and "Option" as used herein
include any  agreements  and related  options for which this  Agreement (and the
Option  granted  hereby) may be  exchanged.  Upon  receipt by Issuer of evidence
reasonably  satisfactory to it of the loss, theft,  destruction or mutilation of
this  Agreement,  and (in the case of loss,  theft or destruction) of reasonably
satisfactory  indemnification,  and  upon  surrender  and  cancellation  of this
Agreement, if mutilated, Issuer will execute and deliver a new Agreement of like
tenor and date.

         SECTION 5. The number of shares of Issuer Common Stock purchasable upon
the exercise of the Option shall be subject to  adjustment  from time to time as
follows:

                  (a) In the event of any change in the type or number of shares
of  Issuer  Common  Stock by  reason  of stock  dividends,  split-ups,  mergers,
recapitalizations,  combinations, subdivisions, conversions, exchanges of shares
or other issuances of additional  shares (other than pursuant to the exercise of
the Option),  the type and number of shares of Issuer  Common Stock  purchasable
upon exercise hereof shall be appropriately  adjusted and proper provision shall
be made so that, in the event that any additional  shares of Issuer Common Stock
are to be issued or otherwise become  outstanding as a result of any such change
(other than  pursuant to an  exercise  of the  Option),  the number of shares of
Issuer  Common  Stock that remain  subject to the Option  shall be  increased or
decreased  (as  applicable)  so that,  after such issuance and together with the
shares of Issuer Common Stock  previously  issued  pursuant to the prior partial
exercise of the Option (as adjusted on account of any of the  foregoing  changes
in the Issuer Common Stock),  such number of shares shall equal the sum of 19.9%
of the  total of the  number  of  shares  of  Issuer  Common  Stock  issued  and
outstanding on the date the Option first becomes exercisable.

                  (b)  Whenever  the  number of shares  of Issuer  Common  Stock
purchasable  upon exercise hereof is adjusted as provided in this Section 5, the
Option  Price shall be adjusted by  multiplying  the Option Price by a fraction,
the  numerator of which shall be equal to the number of shares of Issuer  Common
Stock  purchasable prior to the adjustment and the denominator of which shall be
equal to the  number  of shares of Issuer  Common  Stock  purchasable  after the
adjustment.



                                      -5-
<PAGE>

         SECTION  6. (a) Upon the  occurrence  of a Purchase  Event that  occurs
prior to an Exercise  Termination Event, Issuer shall, at the request of Grantee
(whether on its own behalf or on behalf of any  subsequent  holder of the Option
(or part thereof) or of any of the shares of Issuer Common Stock issued pursuant
hereto),  promptly prepare, file and keep current a shelf registration statement
with the SEC,  under the  Securities Act covering any shares issued and issuable
pursuant to the Option and shall use its  reasonable  best efforts to cause such
registration statement to become effective,  and to remain current and effective
for a period not in excess of 90 days from the day such  registration  statement
first becomes effective, in order to permit the sale or other disposition of any
shares of Issuer  Common  Stock  issued  upon total or partial  exercise  of the
Option ("Option Shares") in accordance with any plan of disposition requested by
Grantee.  Grantee shall have the right to demand two such  registrations,  which
demand right shall be  transferable  but in no event shall Issuer be required to
effect more than two  registrations in the aggregate  pursuant to this Option or
any  subdivision  hereof.  Grantee  shall  provide  all  information  reasonably
requested  by Issuer for  inclusion  in any  registration  statement to be filed
hereunder.  In  connection  with any such  registration  statement,  Issuer  and
Grantee shall provide each other with representations,  warranties,  indemnities
and other agreements customarily given in connection with such registration.  If
requested by Grantee in connection  with such  registration,  Issuer and Grantee
shall become a party to any underwriting  agreement relating to the sale of such
shares,  but  only  to  the  extent  of  obligating  themselves  in  respect  of
representations,   warranties,  indemnities  and  other  agreements  customarily
included in such  underwriting  agreements and reasonably  acceptable to Issuer.
Notwithstanding  the foregoing,  if Grantee revokes any exercise notice or fails
to exercise any Option with respect to any exercise  notice  pursuant to Section
2(e) hereof,  Issuer shall not be obligated to continue any registration process
with  respect to the sale of Option  Shares  issuable  upon the exercise of such
Option and Grantee shall not be deemed to have demanded  registration  of Option
Shares.  If Issuer  withdraws a registration  statement  which has been declared
effective at the request of Grantee,  or any subsequent holder, then such filing
shall be deemed an effective registration for all purposes hereunder. The Issuer
will not be required to file any such  registration  statement during any period
of time  (not to exceed  30 days in the case of  clauses  (A) or (C) below or 45
days in the case of clause (B) below)  when (A) the Issuer is in  possession  of
material   non-public   information  which  it  reasonably   believes  would  be
detrimental to be disclosed at such time and such  information  would have to be
disclosed if a registration statement were filed at that time; (B) the Issuer is
required under the Securities  Act and the rules and  regulations  thereunder to
include  audited  financial  statements  for any  period  in  such  registration
statement and such  financial  statements are not yet available for inclusion in
such registration  statement;  or (C) the Issuer reasonably determines that such
registration  would  interfere  with  any  financing,  acquisition  or  material
transaction  involving  the Issuer.  The  registration  rights set forth in this
Section 6 are subject to the  condition  that the Grantee or  subsequent  holder
shall  provide the Issuer with such  information  with  respect to the  holder's
securities,  the plan for distribution  thereof, and such other information with
respect to the holder  that is  required  under  applicable  securities  laws to
enable the Issuer to include in a  registration  statement  all  material  facts
required to be disclosed  with respect to a registration  thereunder,  including
the identity of the holder and the holder's  plan of  distribution.  The Grantee
shall not be able to exercise its  registration  rights hereunder if Grantee can
rely on Rule 144  promulgated  under the  Securities  Act to sell such number of
shares of Issuer Common Stock that the Grantee otherwise would seek to register.

                  (b)  Concurrently   with  the  preparation  and  filing  of  a
registration  statement  under  Section 6(a) hereof,  Issuer shall also make all
filings  required to comply with state  securities laws in such number of states
as Grantee may reasonably request;  provided,  that Issuer shall not be required
to  qualify  to do  business  in, or  consent  to  service  of  process  in, any
jurisdiction by reason of this provision.



                                      -6-
<PAGE>

         SECTION  7.  Notwithstanding  Sections 2 and 6 hereof,  if Grantee  has
given the notice  referred to in one or more of such  Sections,  the exercise of
the rights  specified in any such Section  shall be extended (a) if the exercise
of such rights requires obtaining  regulatory  approvals (including any required
waiting periods) to the extent necessary to obtain all regulatory  approvals for
the exercise of such rights,  and (b) to the extent necessary to avoid liability
under  Section 16(b) of the Exchange Act by reason of such  exercise;  provided,
that in no event  shall any  closing  date occur  more than 12 months  after the
related  notice date,  and, if the closing date shall not have  occurred  within
such period due to the failure to obtain any required  approval by the FRB, OCC,
FTC, DOJ or any other Governmental Authority despite the reasonable best efforts
of Grantee and Issuer to obtain such approvals, the exercise of the rights shall
be deemed to have been rescinded as of the related notice date. In the event (a)
Grantee  receives  official notice that an approval of the FRB, OCC, FTC, DOJ or
any other  Governmental  Authority  required  for the  purchase  and sale of the
Option  Shares  will not be issued  or  granted  or (b) a  closing  date has not
occurred  within 12 months  after the related  notice date due to the failure to
obtain any such  required  approval,  Grantee  shall be entitled to exercise the
Option in connection with the concurrent resale of the Option Shares pursuant to
a registration statement as provided in Section 6 hereof.

         SECTION 8. Issuer hereby represents and warrants to Grantee as follows:

                  (a) Issuer has the requisite  corporate power and authority to
execute  and  deliver  this  Agreement  and  to  consummate   the   transactions
contemplated  hereby.  The  execution  and  delivery of this  Agreement  and the
consummation of the transactions  contemplated hereby have been duly approved by
the Board of Directors of Issuer and no other corporate  proceedings on the part
of Issuer are  necessary  to  authorize  this  Agreement  or to  consummate  the
transactions  so  contemplated.  This  Agreement  has  been  duly  executed  and
delivered  by,  and  constitutes  a valid and  binding  obligation  of,  Issuer,
enforceable against Issuer in accordance with its terms, subject to any required
Governmental  Approval,  and except as enforceability  thereof may be limited by
applicable bankruptcy, insolvency, reorganization,  moratorium and other similar
laws  affecting  the  enforcement  of  creditors'  rights  generally and general
principles of equity.

                  (b)  Issuer  has  taken  all  necessary  corporate  action  to
authorize and reserve and to permit it to issue,  and at all times from the date
hereof through the  termination  of this Agreement in accordance  with its terms
will have reserved for issuance upon the exercise of the Option,  that number of
shares of Issuer  Common  Stock equal to the maximum  number of shares of Issuer
Common Stock at any time and from time to time issuable hereunder,  and all such
shares, upon issuance pursuant hereto, will be duly authorized,  validly issued,
fully paid, non-assessable,  and will be delivered free and clear of all claims,
liens,  encumbrances  and security  interests and not subject to any  preemptive
rights.

         SECTION  9. (a)  Neither  of the  parties  hereto may assign any of its
rights or delegate  any of its  obligations  under this  Agreement or the Option
created hereunder to any other Person without the express written consent of the
other  party,  except that  Grantee may assign this  Agreement to a wholly owned
subsidiary of Grantee and Grantee may assign its rights hereunder in whole or in
part after the occurrence of a Preliminary Purchase Event. The term "Grantee" as
used in this  Agreement  shall  also be deemed to refer to  Grantee's  permitted
assigns.

                  (b) Any  assignment  of rights  of  Grantee  to any  permitted
assignee of Grantee hereunder shall bear the restrictive legend at the beginning
thereof substantially as follows:

                  The transfer of the option  represented by this assignment and
         the related option agreement is subject to resale restrictions  arising
         under the  Securities  Act of 1933, as amended,  and  applicable  state
         securities laws and to certain  provisions of an agreement



                                      -7-
<PAGE>

         between NBT Bancorp Inc. and BSB Bancorp,  Inc.,  dated as of April 19,
         2000. A copy of such  agreement is on file at the  principal  office of
         BSB,  and will be  provided  to any  permitted  assignee  of the Option
         without charge upon receipt of a written request therefor.

         SECTION 10. Each of Grantee and Issuer will use its reasonable  efforts
to make  all  filings  with,  and to  obtain  consents  of,  all  third  parties
including,  if  applicable,  the  FRB,  OCC,  FTC,  DOJ and  other  Governmental
Authorities  necessary to the consummation of the  transactions  contemplated by
this Agreement.

         SECTION 11. The parties  hereto  acknowledge  that damages  would be an
inadequate remedy for a breach of this Agreement by either party hereto and that
the  obligations  of the parties  hereto  shall be  enforceable  by either party
hereto through injunctive or other equitable relief.  Both parties further agree
to waive any  requirement  for the securing or posting of any bond in connection
with the  obtaining  of any such  equitable  relief and that this  provision  is
without  prejudice to any other rights that the parties  hereto may have for any
failure to perform this Agreement.

         SECTION 12. If any term,  provision,  covenant or restriction contained
in this Agreement is held by a court or a federal or state regulatory  agency of
competent  jurisdiction to be invalid,  void or unenforceable,  the remainder of
the terms, provisions and covenants and restrictions contained in this Agreement
shall remain in full force and effect, and shall in no way be affected, impaired
or  invalidated.  If for any reason such court or regulatory  agency  determines
that  Grantee is not  permitted  to acquire  the full number of shares of Issuer
Common Stock provided in Section 1 hereof (as adjusted pursuant  hereto),  it is
the express intention of Issuer to allow Grantee to acquire or to require Issuer
to  repurchase  such lesser number of shares as may be  permissible  without any
amendment or modification hereof.

         SECTION  13.  All  notices,   requests,   claims,   demands  and  other
communications  hereunder shall be deemed to have been duly given when delivered
in the manner and at the  respective  addresses  of the parties set forth in the
Plan.

         SECTION 14. This  Agreement,  the rights and obligations of the parties
hereto,  and any claims or disputes  relating  thereto  shall be governed by and
construed  in  accordance  with  the  laws of the  State  of  Delaware  (but not
including the choice of law rules thereof).

         SECTION 15. This  Agreement  may be executed in  counterparts,  each of
which shall be deemed to be an original,  but all of which shall  constitute one
and the same  agreement  and shall be  effective  at the time of  execution  and
delivery.

         SECTION 16. Except as otherwise  expressly provided herein, each of the
parties  hereto shall bear and pay all costs and  expenses  incurred by it or on
its behalf in connection with the transactions contemplated hereunder.

         SECTION 17.  Except as otherwise  expressly  provided  herein or in the
Plan,  this  Agreement  contains the entire  agreement  between the parties with
respect to the  transactions  contemplated  hereunder and  supersedes  all prior
arrangements or understandings with respect thereof,  written or oral. The terms
and  conditions of this  Agreement  shall inure to the benefit of and be binding
upon the parties hereto and their respective  successors and permitted  assigns.
Nothing in this Agreement,  expressed or implied, is intended to confer upon any
party, other than the parties hereto, and their respective  successors except as
assigns, any rights, remedies,  obligations or liabilities under or by reason of
this Agreement, except as expressly provided herein.



                                      -8-
<PAGE>

         SECTION 18.  Capitalized  terms used in this  Agreement and not defined
herein but defined in the Plan shall have the meanings assigned therein.

         SECTION 19.  Nothing  contained  in this  Agreement  shall be deemed to
authorize  or require  Issuer or Grantee to breach any  provision of the Plan or
any provision of law applicable to the Grantee or Issuer.

         SECTION 20. In the event that any selection or  determination  is to be
made  by  Grantee  or a  subsequent  holder  hereunder  and at the  time of such
selection  or  determination  there is more than one  Grantee or  holders,  such
selection shall be made by a majority in interest of such Grantees or holders.

         SECTION  21. In the event of any  exercise  of the  option by  Grantee,
Issuer and such  Grantee  shall  execute  and deliver  all other  documents  and
instruments and take all other action that may be reasonably  necessary in order
to consummate the transactions provided for by such exercise.

         SECTION 22. Except to the extent Grantee exercises the Option,  Grantee
shall have no rights to vote or receive  dividends or have any other rights as a
shareholder with respect to shares of Issuer Common Stock covered hereby.

                            [SIGNATURE PAGE FOLLOWS]



                                      -9-
<PAGE>

         IN  WITNESS  WHEREOF,  each  of the  parties  has  caused  this  Option
Agreement  to be  executed  and  delivered  on its  behalf  by their  respective
officers thereunto duly authorized, all as of the date first above written.

                                     NBT BANCORP INC.


                                     By:    /s/ Daryl R. Forsythe
                                            ------------------------------------
                                     Name:  Daryl R. Forsythe
                                     Title: President and Chief Executive
                                            Officer



                                     BSB BANCORP, INC.


                                     By:    /s/ Thomas L. Thorn
                                            ------------------------------------
                                     Name:  Thomas L. Thorn
                                     Title: Acting President and Chief Executive
                                            Officer



<PAGE>

                                                                       Exhibit D


                              CERTIFICATE OF MERGER

                                BSB BANCORP, INC.
                                      INTO
                                NBT BANCORP INC.


                  Pursuant to Title 8,  Section  251 of the General  Corporation
Law of the State of Delaware,  NBT Bancorp  Inc., a  corporation  organized  and
existing under the law of the State of Delaware ("NBT"), hereby certifies to the
following  facts  relating to the merger of BSB  Bancorp,  Inc.,  a  corporation
organized and existing under the law of the State of Delaware ("BSB"),  with and
into NBT:

                  FIRST: The name and state of incorporation of each constituent
entity that is a party to the merger is as follows:

                 Name                               State of Incorporation
                 ----                               ----------------------

           NBT Bancorp Inc.                                Delaware

           BSB Bancorp, Inc.                               Delaware


                  SECOND:  An  Agreement  and Plan of Merger,  dated as of April
___, 2000, by and between NBT and BSB (the "Agreement and Plan of Merger"),  has
been approved,  adopted,  certified,  executed and  acknowledged  by each of the
constituent  corporations in accordance with the  requirements of Section 251 of
the General Corporation Law of the State of Delaware.

                  THIRD:  (a) Pursuant to the Agreement and Plan of Merger,  the
surviving  corporation  of the  merger  is  NBT,  a  Delaware  corporation  (the
"Surviving  Corporation"),   and  the  name  of  the  Surviving  Corporation  is
"____________".

                           (b)   Article   FOURTH   of   the    Certificate   of
Incorporation of the Surviving Corporation is amended to read as follows:

                           "FOURTH: The total number of shares of all classes of
                           stock which the Corporation  shall have the authority
                           to issue is One Hundred  Five  Million  (105,000,000)
                           shares,    consisting   of   One   Hundred    Million
                           (100,000,000)  shares  of Common  Stock  having a par
                           value of $.01 per share and Five


<PAGE>

                           Million  (5,000,000) shares of Preferred Stock having
                           a par value of $.01 per share."

                  FOURTH:  At the  "Effective  Time" of the  merger  as  defined
below,  the certificate of  incorporation of NBT shall become the certificate of
incorporation of the Surviving  Corporation with the amendments described above,
until amended in accordance  with the provisions of the General  Corporation Law
of the State of Delaware.  At the Effective Time, the bylaws of NBT shall become
the bylaws of the Surviving  Corporation,  until amended in accordance  with the
certificate of incorporation of NBT and the General Corporation Law of the State
of Delaware.  At the Effective Time, the directors of the Surviving  Corporation
will be the following  individuals:  ________________________.  At the Effective
Time, the officers of the Surviving Corporation shall be as set forth in Exhibit
E to the Agreement and Plan of Merger.

                  FIFTH: The executed Agreement and Plan of Merger is on file at
the office of the Surviving Corporation at the following address:

                           _________________
                           56-68 Exchange Street
                           Binghamton, New York 13902

                  SIXTH:  A copy of the  Agreement  and Plan of  Merger  will be
furnished by the  Surviving  Corporation,  on request and without  cost,  to any
stockholder of any constituent corporation.

                            [SIGNATURE PAGE FOLLOWS]


<PAGE>


         IN WITNESS  WHEREOF,  NBT has caused this  Certificate  of Merger to be
duly  executed  as of this __ day of , 2000,  to be  effective  at _____ p.m. on
_________ ___, 2000.



ATTEST                                NBT BANCORP INC.
By:                                   By:
   ------------------------------         ----------------------------
Name:                                 Name:
Title:                                Title:






<PAGE>

                                                                       EXHIBIT E

                            SENIOR EXECUTIVE OFFICERS
                            -------------------------



Daryl R. Forsythe                Chairman, President and Chief Executive Officer
William C. Craine                Vice Chairman
Joe C. Minor                     Treasurer
Larry G. Denniston               Secretary





<PAGE>


                                                                       Exhibit F


                                BSB BANCORP, INC.

                              STOCKHOLDER AGREEMENT


                  This  STOCKHOLDER  AGREEMENT,  dated as of April 19, 2000,  is
entered into by and among NBT Bancorp Inc., a Delaware  corporation ("NBT"), and
the  stockholders  of  BSB  Bancorp,   Inc.,  a  Delaware  corporation  ("BSB"),
identified  on Schedule I hereto  (collectively,  the  "Stockholders"),  who are
directors,  executive  officers or other affiliates of BSB (for purposes of Rule
145 under the Securities Act of 1933, as amended, and for purposes of qualifying
the Merger (defined below) for "pooling-of-interests" accounting treatment).

                  WHEREAS,  NBT and BSB have entered into an Agreement  and Plan
of Merger,  dated as of April 19, 2000 (the  "Agreement"),  which is conditioned
upon the execution of this  Stockholder  Agreement and which provides for, among
other  things,  the  merger  of BSB  with  and into  NBT,  in a  stock-for-stock
transaction (the "Merger"); and

                  WHEREAS,  in order to induce NBT to enter into and  consummate
the Agreement,  each of the Stockholders  agrees to, among other things, vote in
favor of the Agreement,  the Merger and the other  transactions  contemplated by
the Agreement in his or her capacity as a stockholder of BSB;

                  NOW,  THEREFORE in consideration  of the premises,  the mutual
covenants  and   agreements  set  forth  herein  and  other  good  and  valuable
consideration,  the  sufficiency  of which is hereby  acknowledged,  the parties
hereto agree as follows:

         1.  OWNERSHIP OF BSB COMMON  STOCK.  Each  Stockholder  represents  and
warrants that the number of shares of BSB common stock, par value $.01 per share
("BSB Common Stock"),  set forth opposite such  Stockholder's name on Schedule I
hereto is the total  number of shares of BSB Common Stock over which such person
has "beneficial ownership" within the meaning of Rule 13d-3 under the Securities
Exchange  Act  of  1934,  as  amended,   except  that  the  provisions  of  Rule
13d-3(d)(1)(i) shall be considered without any limit as to time.

         2.  AGREEMENTS  OF THE  STOCKHOLDERS.  Each  Stockholder  covenants and
agrees that:

                  (a) Such  Stockholder  shall, at any meeting of the holders of
any or all classes or series of BSB Common  Stock  called for the purpose (or in
connection with any action taken by written consent),  vote or cause to be voted
all shares of BSB Common Stock with respect to which such Stockholder has voting
power  (including the power to vote or to direct the voting of) whether owned as
of the  date  hereof  or  hereafter  acquired  (the  "Shares")  in  favor of the
Agreement, the Merger and the other transactions  contemplated by the Agreement.
Notwithstanding  the  foregoing,  or any  other  provision  of this  Stockholder
Agreement,  NBT shall have no agreement,  arrangement or understanding  with any
Stockholder  as to directing the voting of any shares of BSB Common Stock to the
extent it would result in NBT,  individually  or with any of its  Affiliates (as
defined in the next  sentence) or Associates  (as defined in the next  sentence)
becoming the Beneficial  Owner (as defined in the next sentence) of five percent
or more of the Voting Stock (as defined in the next  sentence) of BSB. The terms
"Affiliates,"  "Associates,"  "Beneficial  Owner,"  and  "Voting  Stock"  are as
defined or referenced in Article 14 of the BSB Certificate of Incorporation.  In
determining  which,  if any,  Stockholder  that  NBT  shall  have no  agreement,
arrangement  or  understanding  with as to directing the voting of any shares of
BSB Common Stock,  reference  shall be made to the  Stockholders in order of the
amount of BSB  Common  Stock  set  forth  opposite  such  Stockholder's  name on
Schedule I hereto,  beginning with the Stockholder who reports the fewest number
of shares, and continuing in ascending order therefrom.


<PAGE>


                  (b) Stockholder  hereby agrees to timely deliver to NBT a duly
executed  proxy in the form  attached  hereto as Exhibit A (the  "Proxy"),  such
Proxy to cover all of the  Shares.  In the event that  Stockholder  is unable to
provided  any such Proxy in a timely  manner,  Stockholder  hereby  grants NBT a
power of  attorney  to  execute  and  deliver  such  Proxy  for and on behalf of
Stockholder, such power of attorney, which being coupled with an interest, shall
survive  any death,  disability,  bankruptcy,  or any other such  impediment  of
Stockholder.  Upon  execution  of this  Stockholder  Agreement  by  Stockholder,
Stockholder hereby revokes any and all prior proxies or powers of attorney given
by  Stockholder  with respect to the Shares and agrees not grant any  subsequent
proxies or powers of attorney  with  respect to the Shares  until the earlier of
(i) such date and time as the Merger shall become  effective in accordance  with
the terms and  provisions  of the Agreement or (ii) the date of  termination  of
this Stockholder Agreement pursuant to Section 4 hereto.

                  (c)  Except as  otherwise  expressly  permitted  hereby,  such
Stockholder shall not sell, pledge,  transfer or otherwise dispose of his or her
shares of BSB Common Stock; provided,  however, that this Section 2(c) shall not
apply to a pledge existing as of January 1, 2000.

                  (d) Such  Stockholder  shall not in his or her  capacity  as a
stockholder of BSB directly or indirectly encourage or solicit, initiate or hold
discussions or  negotiations  with, or provide any  information  to, any person,
entity or group (other than NBT or an affiliate thereof)  concerning any merger,
sale  of  all or  substantially  all of the  assets  or  liabilities  not in the
ordinary  course  of  business,  sale of  shares  of  capital  stock or  similar
transaction  involving BSB or otherwise  inconsistent  with the Agreement or the
transactions   contemplated   thereby.   Nothing   herein   shall   impair  such
Stockholder's fiduciary obligations as a director of BSB.

                  (e)  Stockholder  shall use his or her best efforts to take or
cause  to be  taken  all  action,  and to do or  cause  to be  done  all  things
necessary,  proper  or  advisable  under  applicable  laws  and  regulations  to
consummate and make effective the Merger contemplated by the Agreement.

                  (f) Such Stockholder shall not, prior to the public release by
NBT of an  earnings  report to its  stockholders  covering at least one month of
operations  after  consummation of the Merger (the "Restricted  Period"),  sell,
pledge (other than the  replacement  of a pledge  existing on January 1, 2000 of
BSB Common  Stock),  transfer or  otherwise  dispose of the shares of NBT common
stock, par value $.01 per share (the "NBT Common Stock").

                  (g) Such Stockholder shall comply with all applicable  federal
and  state  securities  laws in  connection  with any sale of NBT  Common  Stock
received in exchange for BSB Common Stock in the Merger,  including  the trading
and volume limitations as to sales by affiliates contained in Rule 145 under the
Securities Act of 1933, as amended.

         3. SUCCESSORS AND ASSIGNS. A Stockholder may sell, pledge,  transfer or
otherwise  dispose of his or her shares of BSB Common  Stock only with the prior
written  consent of NBT and if the  acquirer of such BSB Common  Stock agrees in
writing to be bound by this Stockholder Agreement.


                                       2


<PAGE>


         4.  TERMINATION.  The parties  agree and intend  that this  Stockholder
Agreement  be a valid and  binding  agreement  enforceable  against  the parties
hereto  and that  damages  and  other  remedies  at law for the  breach  of this
Stockholder  Agreement  are  inadequate.   This  Stockholder  Agreement  may  be
terminated  at any time prior to the  consummation  of the Merger by the written
consent of the parties hereto and shall be automatically terminated in the event
that the  Agreement  is  terminated  in  accordance  with its  terms;  provided,
however,  that if the holders of BSB Common Stock fail to approve the  Agreement
or BSB fails to hold a stockholders' meeting to vote on the Agreement,  then (i)
Section  2(a)  clause  (ii)  hereof  shall  continue in effect as to any plan or
proposal received by BSB from any person, entity or group (other than NBT or any
affiliate  thereof) prior to the termination of the Agreement or within 240 days
after such  termination  ("Plan or Proposal") and (ii) Section 2(c) hereof shall
continue in effect to preclude a sale  (other  than  pursuant to normal  brokers
transactions  on the Nasdaq  Stock  Market),  pledge  (other than to a bona fide
financial  institution  or  recognized  securities  dealer),  transfer  or other
disposition  directly  or  indirectly  to any such  person,  entity  or group in
connection with any such Plan or Proposal, except upon consummation of such Plan
or Proposal.

         5. NOTICES.  Notices may be provided to NBT and the Stockholders in the
manner specified in the Agreement,  with all notices to the  Stockholders  being
provided to them at the addresses set forth at Schedule I.

         6. GOVERNING LAW. This  Stockholder  Agreement shall be governed by the
laws of the  State of  Delaware,  without  giving  effect to the  principles  of
conflicts of laws thereof.

         7. COUNTERPARTS.  This Stockholder  Agreement may be executed in one or
more counterparts, all of which shall be considered one and the same and each of
which shall be deemed an original.

         8. HEADINGS.  The Section  headings  contained herein are for reference
purposes only and shall not affect in any way the meaning or  interpretation  of
this Stockholder Agreement.

         9. REGULATORY APPROVAL.  If any provision of this Stockholder Agreement
requires the approval of any  regulatory  authority in order to be  enforceable,
then such  provision  shall not be  effective  until such  approval is obtained;
provided, however, that the foregoing shall not affect the enforceability of any
other provision of this Stockholder Agreement.

                             SIGNATURE PAGE FOLLOWS


                                       3


<PAGE>




                  IN WITNESS  WHEREOF,  NBT, by a duly authorized  officer,  and
each of the Stockholders  have caused this Stockholder  Agreement to be executed
and delivered as of the day and year first above written.

NBT BANCORP INC.


By:
  -------------------------
      Daryl R. Forsythe
      President and Chief Executive Officer






STOCKHOLDERS:

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


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


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


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


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


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


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


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


<PAGE>




                                   SCHEDULE I

                                                  Number of Shares of BSB Common
Name and Address of Stockholder                     Stock Beneficially Owned
- -------------------------------                     ------------------------

Ferris G. Akel                                             166,008
221 Riverside Drive
Binghamton, NY  13905

Robert W. Allen                                             36,917
2400 Ballybunion Road
Center Valley, PA  18034

Diane J. Bendz                                              12,000
246 Mason Road
Vestal, NY  13850

William C. Craine                                           90,156
Fifty-Three Chenango Avenue
Sherbourne, NY  13460-0717

John P. Driscoll                                            50,843
4 West Lake Street
Skaneateles, NY  13152

Ann G. Higbee                                               18,150
3391 East Lake Road
Skaneateles, NY  13152

Thomas F. Kelly                                             24,112
48 Coventry Road
Endicott, NY  13760

David A. Niermeyer                                          22,675
224 Meeker Road
Vestal, NY  13850

Mark T. O'Neil, Jr.                                         23,042
195 Gatewood Blvd
Apalachin, NY  13732

William H. Rincker                                         136,107
2153 E. Hamton Road
Binghamton, NY  13903

Thomas L. Thorn                                            226,837
400 Bradford Parkway
Syracuse, NY  13224

Rexford C. Decker                                           24,685
30 Port Street
Port Crane, NY  13833


Larry G. Denniston                                          53,772
8 Devon Blvd.
Binghamton, NY  13903

Douglas R. Johnson                                          42,290
32 Margaret Street
Johnson City, NY  13790

Matthew W. Schaefer                                         16,975
329 Doris Avenue
Vestal, NY  13850

Glenn R. Small                                             116,463
112 South Meadowbrook Lane
Vestal, NY  13850

Art C. Smith                                                71,869
48 Margaret Street
Johnson City, NY  13790





<PAGE>




                                IRREVOCABLE PROXY

                                TO VOTE STOCK OF

                                BSB BANCORP, INC.


                  The undersigned  stockholder of BSB Bancorp,  Inc., a Delaware
corporation  ("BSB"),  hereby  irrevocably (to the full extent  permitted by the
Delaware General Corporation Law) appoints the members of the Board of Directors
of NBT Bancorp Inc., a Delaware  corporation  ("NBT"),  and each of them, or any
other  designee of NBT, as the sole and  exclusive  attorneys and proxies of the
undersigned,  with full power of substitution  and  resubstitution,  to vote and
exercise all voting and related rights (to the full extent that the  undersigned
is entitled to do so) with respect to all of the shares of capital  stock of BSB
that now are or hereafter may be beneficially owned by the undersigned,  and any
and all other shares or securities of BSB issued or issuable in respect  thereof
on or after the date hereof (collectively,  the "Shares") in accordance with the
terms  of  this  Irrevocable  Proxy.  The  Shares   beneficially  owned  by  the
undersigned  stockholder  of BSB as of the date of this  Irrevocable  Proxy  are
listed on the  final  page of this  Irrevocable  Proxy.  Upon the  undersigned's
execution of this  Irrevocable  Proxy,  any and all prior  proxies  given by the
undersigned  with respect to any Shares are hereby  revoked and the  undersigned
agrees not to grant any  subsequent  proxies  with  respect to the Shares  until
after the Expiration Date (as defined below).

                  This Irrevocable  Proxy is irrevocable (to the extent provided
in  the  Delaware  General  Corporation  Law),  is  coupled  with  an  interest,
including, but not limited to that certain Agreement and Plan of Merger dated as
of even date  herewith by and between NBT and BSB  ("Merger  Agreement")  and is
granted in  consideration  of NBT  entering  into the Merger  Agreement  for the
merger of BSB into NBT (the  "Merger").  As used  herein,  the term  "Expiration
Date"  shall  mean the  earlier to occur of (i) such date and time as the Merger
shall become effective in accordance with the terms and provisions of the Merger
Agreement, and (ii) the date of termination of the Merger Agreement.

                  The attorneys  and proxies  named above,  and each of them are
hereby  authorized  and empowered by the  undersigned,  at any time prior to the
Expiration  Date,  to act as the  undersigned's  attorney  and proxy to vote the
Shares,  and to exercise  all voting and other  rights of the  undersigned  with
respect to the Shares (including,  without limitation,  the power to execute and
deliver written consents  pursuant to the Delaware General  Corporation Law), at
every annual,  special or adjourned  meeting of the  stockholders  of BSB and in
every written consent in lieu of such meeting:

                  in favor of approval and adoption of the Merger  Agreement and
                  of the transactions contemplated thereby.

                  The  attorneys  and proxies  named above may not exercise this
Irrevocable  Proxy on any other matter except as provided above. The undersigned
stockholder may vote the Shares on all other matters.

                  All  authority  herein  conferred  shall  survive the death or
incapacity of the undersigned  and any obligation of the  undersigned  hereunder
shall be  binding  upon the  heirs,  personal  representatives,  successors  and
assigns of the undersigned.



<PAGE>



                  This  Irrevocable  Proxy  shall  terminate  on,  and  be of no
further force or effect after, the Expiration Date.





                            (SIGNATURE PAGE FOLLOWS)


                                       2


<PAGE>



                  This  Irrevocable   Proxy  is  coupled  with  an  interest  as
aforesaid and is irrevocable.


Dated:  April ___, 2000


                                --------------------------------------
                                (Signature of Stockholder)





                                --------------------------------------
                                (Print Name of Stockholder)





                                Shares beneficially owned:






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














                       SIGNATURE PAGE TO IRREVOCABLE PROXY


                                       3


<PAGE>


                                                                       Exhibit G



                                NBT BANCORP INC.

                              STOCKHOLDER AGREEMENT


                  This  STOCKHOLDER  AGREEMENT,  dated as of April 19, 2000,  is
entered into by and among BSB Bancorp Inc., a Delaware  corporation ("BSB"), and
the stockholders of NBT Bancorp Inc., a Delaware corporation ("NBT"), identified
on Schedule I hereto  (collectively,  the  "Stockholders"),  who are  directors,
executive  officers or other  affiliates  of NBT (for purposes of Rule 145 under
the  Securities  Act of 1933,  as amended,  and for purposes of  qualifying  the
Merger (defined below) for "pooling-of-interests" accounting treatment).

                  WHEREAS,  NBT and BSB have entered into an Agreement  and Plan
of Merger,  dated as of April 19, 2000 (the  "Agreement"),  which is conditioned
upon the execution of this  Stockholder  Agreement and which provides for, among
other  things,  the  merger  of BSB  with  and into  NBT,  in a  stock-for-stock
transaction (the "Merger"); and

                  WHEREAS,  in order to induce BSB to enter into and  consummate
the Agreement,  each of the Stockholders  agrees to, among other things, vote in
favor of the Agreement,  the Merger and the other  transactions  contemplated by
the Agreement in his or her capacity as a stockholder of NBT;

                  NOW,  THEREFORE in consideration  of the premises,  the mutual
covenants  and   agreements  set  forth  herein  and  other  good  and  valuable
consideration,  the  sufficiency  of which is hereby  acknowledged,  the parties
hereto agree as follows:

         1.  OWNERSHIP OF NBT COMMON  STOCK.  Each  Stockholder  represents  and
warrants that the number of shares of NBT common stock, par value $.01 per share
("NBT Common Stock"),  set forth opposite such  Stockholder's name on Schedule I
hereto is the total  number of shares of NBT Common Stock over which such person
has "beneficial ownership" within the meaning of Rule 13d-3 under the Securities
Exchange  Act  of  1934,  as  amended,   except  that  the  provisions  of  Rule
13d-3(d)(1)(i) shall be considered without any limit as to time.

         2.  AGREEMENTS  OF THE  STOCKHOLDERS.  Each  Stockholder  covenants and
agrees that:

                  (a) Such  Stockholder  shall, at any meeting of the holders of
any or all classes or series of NBT Common  Stock  called for the purpose (or in
connection with any action taken by written consent),  vote or cause to be voted
all shares of NBT Common Stock with respect to which such Stockholder has voting
power  (including the power to vote or to direct the voting of) whether owned as
of the  date  hereof  or  hereafter  acquired  (the  "Shares")  in  favor of the
Agreement, the Merger and the other transactions  contemplated by the Agreement.
Notwithstanding  the  foregoing,  or any  other  provision  of this  Stockholder
Agreement,  BSB shall have no agreement,  arrangement or understanding  with any
Stockholder  as to directing the voting of any shares of NBT Common Stock to the
extent it would result in NBT,  individually  or with any of its  Affiliates (as
defined in the next  sentence) or Associates  (as defined in the next  sentence)
becoming the Beneficial  Owner (as defined in the next sentence) of five percent
or more of the Voting Stock (as defined in the next  sentence) of NBT. The terms
"Affiliates,"  "Associates,"  "Beneficial  Owner,"  and  "Voting  Stock"  are as
defined or referenced in Article 11 of the NBT Certificate of Incorporation.  In
determining  which,  if any,  Stockholder  that  BSB  shall  have no  agreement,
arrangement  or  understanding  with as to directing the voting of any shares of
NBT Common Stock,  reference  shall be made to the  Stockholders in order of the
amount of NBT  Common  Stock  set  forth  opposite  such  Stockholder's  name on
Schedule I hereto,  beginning with the Stockholder who reports the fewest number
of shares, and continuing in ascending order therefrom.


<PAGE>


                  (b) Stockholder  hereby agrees to timely deliver to BSB a duly
executed  proxy in the form  attached  hereto as Exhibit A (the  "Proxy"),  such
Proxy to cover all of the  Shares.  In the event that  Stockholder  is unable to
provided  any such Proxy in a timely  manner,  Stockholder  hereby  grants BSB a
power of  attorney  to  execute  and  deliver  such  Proxy  for and on behalf of
Stockholder, such power of attorney, which being coupled with an interest, shall
survive  any death,  disability,  bankruptcy,  or any other such  impediment  of
Stockholder.  Upon  execution  of this  Stockholder  Agreement  by  Stockholder,
Stockholder hereby revokes any and all prior proxies or powers of attorney given
by  Stockholder  with respect to the Shares and agrees not grant any  subsequent
proxies or powers of attorney  with  respect to the Shares  until the earlier of
(i) such date and time as the Merger shall become  effective in accordance  with
the terms and  provisions  of the Agreement or (ii) the date of  termination  of
this Stockholder Agreement pursuant to Section 4 hereto.

                  (c)  Except as  otherwise  expressly  permitted  hereby,  such
Stockholder shall not sell, pledge,  transfer or otherwise dispose of his or her
shares of NBT Common Stock; provided,  however, that this Section 2(c) shall not
apply to a pledge existing as of January 1, 2000.

                  (d) Such  Stockholder  shall not in his or her  capacity  as a
stockholder of NBT directly or indirectly encourage or solicit, initiate or hold
discussions or  negotiations  with, or provide any  information  to, any person,
entity or group (other than BSB or an affiliate thereof)  concerning any merger,
sale  of  all or  substantially  all of the  assets  or  liabilities  not in the
ordinary  course  of  business,  sale of  shares  of  capital  stock or  similar
transaction  involving NBT or otherwise  inconsistent  with the Agreement or the
transactions   contemplated   thereby.   Nothing   herein   shall   impair  such
Stockholder's fiduciary obligations as a director of NBT.

                  (e)  Stockholder  shall use his or her best efforts to take or
cause  to be  taken  all  action,  and to do or  cause  to be  done  all  things
necessary,  proper  or  advisable  under  applicable  laws  and  regulations  to
consummate and make effective the Merger contemplated by the Agreement.

                  (f) Such Stockholder shall not, prior to the public release by
NBT of an  earnings  report to its  stockholders  covering at least one month of
operations  after  consummation of the Merger (the "Restricted  Period"),  sell,
pledge (other than the  replacement  of a pledge  existing on January 1, 2000 of
NBT Common  Stock),  transfer or  otherwise  dispose of his or her shares of NBT
common stock, par value $.01 per share (the "NBT Common Stock").

         3. SUCCESSORS AND ASSIGNS. A Stockholder may sell, pledge,  transfer or
otherwise  dispose of his or her shares of NBT Common  Stock only with the prior
written  consent of BSB and if the  acquirer of such NBT Common  Stock agrees in
writing to be bound by this Stockholder Agreement.

         4.  TERMINATION.  The parties  agree and intend  that this  Stockholder
Agreement  be a valid and  binding  agreement  enforceable  against  the parties
hereto  and that  damages  and  other  remedies  at law for the  breach  of this
Stockholder  Agreement  are  inadequate.   This  Stockholder  Agreement  may  be
terminated  at any time prior to the  consummation  of the Merger by the written
consent of the parties hereto and shall be automatically terminated in the event
that the  Agreement  is  terminated  in  accordance  with its  terms;  provided,
however,  that if the holders of NBT Common Stock fail to approve the  Agreement
or NBT fails to hold a stockholders' meeting to vote on the Agreement,  then (i)
Section  2(a)  clause  (ii)  hereof  shall  continue in effect as to any plan or
proposal  received  by NBT from any  person,  entity  or group  (other  than NBT
Bancorp or any affiliate  thereof) prior to the  termination of the Agreement or
within 240 days after such  termination  ("Plan or  Proposal")  and (ii) Section
2(c) hereof shall  continue in effect to preclude a sale (other than pursuant to
normal brokers transactions on the Nasdaq Stock Market), pledge (other than to a
bona fide financial  institution or recognized  securities dealer),  transfer or
other disposition directly or indirectly to any such person,  entity or group in
connection with any such Plan or Proposal, except upon consummation of such Plan
or Proposal.


                                       2


<PAGE>


         5. NOTICES.  Notices may be provided to BSB and the Stockholders in the
manner specified in the Agreement,  with all notices to the  Stockholders  being
provided to them at the addresses set forth at Schedule I.

         6. GOVERNING LAW. This  Stockholder  Agreement shall be governed by the
laws of the  State of  Delaware,  without  giving  effect to the  principles  of
conflicts of laws thereof.

         7. COUNTERPARTS.  This Stockholder  Agreement may be executed in one or
more counterparts, all of which shall be considered one and the same and each of
which shall be deemed an original.

         8. HEADINGS.  The Section  headings  contained herein are for reference
purposes only and shall not affect in any way the meaning or  interpretation  of
this Stockholder Agreement.

         9. REGULATORY APPROVAL.  If any provision of this Stockholder Agreement
requires the approval of any  regulatory  authority in order to be  enforceable,
then such  provision  shall not be  effective  until such  approval is obtained;
provided, however, that the foregoing shall not affect the enforceability of any
other provision of this Stockholder Agreement.

                             SIGNATURE PAGE FOLLOWS


                                       3


<PAGE>


                  IN WITNESS  WHEREOF,  BSB, by a duly authorized  officer,  and
each of the Stockholders  have caused this Stockholder  Agreement to be executed
and delivered as of the day and year first above written.

BSB BANCORP, INC.


By:
   ----------------------------------






STOCKHOLDERS:

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


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


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


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


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


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


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


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





<PAGE>




                                   SCHEDULE I

                                                  Number of Shares of NBT Common
Name and Address of Stockholder                     Stock Beneficially Owned
- -------------------------------                     ------------------------









<PAGE>


                                IRREVOCABLE PROXY

                                TO VOTE STOCK OF

                                NBT BANCORP INC.


                  The  undersigned  stockholder  of NBT Bancorp Inc., a Delaware
corporation  ("NBT"),  hereby  irrevocably (to the full extent  permitted by the
Delaware General Corporation Law) appoints the members of the Board of Directors
of BSB Bancorp,  Inc., a Delaware  corporation ("BSB"), and each of them, or any
other  designee of BSB, as the sole and  exclusive  attorneys and proxies of the
undersigned,  with full power of substitution  and  resubstitution,  to vote and
exercise all voting and related rights (to the full extent that the  undersigned
is entitled to do so) with respect to all of the shares of capital  stock of NBT
that now are or hereafter may be beneficially owned by the undersigned,  and any
and all other shares or securities of NBT issued or issuable in respect  thereof
on or after the date hereof (collectively,  the "Shares") in accordance with the
terms  of  this  Irrevocable  Proxy.  The  Shares   beneficially  owned  by  the
undersigned  stockholder  of NBT as of the date of this  Irrevocable  Proxy  are
listed on the  final  page of this  Irrevocable  Proxy.  Upon the  undersigned's
execution of this  Irrevocable  Proxy,  any and all prior  proxies  given by the
undersigned  with respect to any Shares are hereby  revoked and the  undersigned
agrees not to grant any  subsequent  proxies  with  respect to the Shares  until
after the Expiration Date (as defined below).

                  This Irrevocable  Proxy is irrevocable (to the extent provided
in  the  Delaware  General  Corporation  Law),  is  coupled  with  an  interest,
including, but not limited to that certain Agreement and Plan of Merger dated as
of even date  herewith by and between NBT and BSB  ("Merger  Agreement")  and is
granted in  consideration  of BSB  entering  into the Merger  Agreement  for the
merger of BSB into NBT (the  "Merger").  As used  herein,  the term  "Expiration
Date"  shall  mean the  earlier to occur of (i) such date and time as the Merger
shall become effective in accordance with the terms and provisions of the Merger
Agreement, and (ii) the date of termination of the Merger Agreement.

                  The attorneys  and proxies  named above,  and each of them are
hereby  authorized  and empowered by the  undersigned,  at any time prior to the
Expiration  Date,  to act as the  undersigned's  attorney  and proxy to vote the
Shares,  and to exercise  all voting and other  rights of the  undersigned  with
respect to the Shares (including,  without limitation,  the power to execute and
deliver written consents  pursuant to the Delaware General  Corporation Law), at
every annual,  special or adjourned  meeting of the  stockholders  of NBT and in
every written consent in lieu of such meeting:

                  in favor of approval and adoption of the Merger  Agreement and
                  of the transactions contemplated thereby.

                  The  attorneys  and proxies  named above may not exercise this
Irrevocable  Proxy on any other matter except as provided above. The undersigned
stockholder may vote the Shares on all other matters.

                  All  authority  herein  conferred  shall  survive the death or
incapacity of the undersigned  and any obligation of the  undersigned  hereunder
shall be  binding  upon the  heirs,  personal  representatives,  successors  and
assigns of the undersigned.



<PAGE>



                  This  Irrevocable  Proxy  shall  terminate  on,  and  be of no
further force or effect after, the Expiration Date.





                                             (SIGNATURE PAGE FOLLOWS)







<PAGE>



                  This  Irrevocable   Proxy  is  coupled  with  an  interest  as
aforesaid and is irrevocable.


Dated:  April ___, 2000






                                 ------------------------------------
                                 (Signature of Stockholder)





                                 ------------------------------------
                                 (Print Name of Stockholder)




                                 Shares beneficially owned:







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







                       SIGNATURE PAGE TO IRREVOCABLE PROXY






                                  EXHIBIT 99.1

                                  PRESS RELEASE

Business Editors

         NORWICH,  NY/BINGHAMTON,  NY--(BUSINESS  WIRE)--April  20,  2000 -- NBT
Bancorp Inc. (NBT) and BSB Bancorp,  Inc. (BSB) today announced the signing of a
definitive  agreement  to merge.  This  strategic  alliance  will  create a bank
holding company with assets of $4.7 billion and proforma  market  capitalization
of approximately $539 million.  The holding company will adopt a new name before
the merger occurs.
         Under the terms of the  agreement,  BSB  stockholders  will receive two
shares of NBT common stock for each share of BSB held.  The  combined  company's
15-seat board of directors  will be made up of seven  directors from BSB and six
from  NBT  plus  one  from  NBT's  newly  acquired  Lake  Ariel  Bancorp,   Inc.
Pennsylvania subsidiary and one from the Pioneer American Holding Company Corp.,
subject to the closing of the merger of that company  with NBT. The  transaction
will  be  a  tax-free  exchange  of  shares  and  will  be  accounted  for  as a
pooling-of-interests.  Based upon NBT's  closing  share price on April 19, 2000,
the  transaction  values each BSB share at $24, a premium of 34 percent to BSB's
closing  share  price on that  date.  The  total  transaction  is valued at $251
million.  Common  stockholders  of NBT will have ownership of  approximately  53
percent  of the  combined  company  while  BSB's  common  stockholders  will own
approximately 47 percent,  assuming  consummation of NBT's previously  announced
agreement to merge with Pioneer American Holding Company Corp.
         As a result of the merger, the principal banking subsidiaries, NBT Bank
and BSB Bank & Trust, will be combined to create one of the largest  independent
community  banks in upstate New York.  The new bank will serve 12 counties  from
more than 55 offices and over 100 ATMs. The resulting bank will adopt a new name
prior to the merger.  The  combined  company  will have three  direct  operating
subsidiaries including two community banks and a financial services company.
         NBT Financial  Services,  Inc. was created in September of last year to
concentrate on expanding  NBT's menu of financial  services  beyond  traditional
bank product  offerings.  The company  recently  announced the acquisition of M.
Griffith,  Inc., a securities firm in Utica, NY, offering investment,  financial
advisory and asset-management services. Following the merger of NBT and BSB, the
financial services company will be given a new name that correlates with the new
holding  company  and bank  names.  Joe C.  Minor will  continue  in his role as
president  of NBT  Financial  Services and will assume the position of its chief
executive officer. This subsidiary,  which will include the trust and investment
division,  will be based in Norwich,  NY. The Trust and Investment Division will
be managed by BSB senior vice  president  Douglas  Johnson  upon the  previously
announced  retirement,  at merger closing,  of NBT executive vice president John
Roberts.
         LA Bank,  whose corporate  offices are located in Scranton,  PA, joined
NBT as a result of the merger with Lake Ariel  Bancorp,  Inc.  on  February  17,
2000.  NBT has a definitive  agreement to merge with  Pioneer  American  Holding
Company Corp., also based in northeastern Pennsylvania. NBT announced today that
the  Board  of  Governors  of the  Federal  Reserve  System  and  the  State  of
Pennsylvania  Department  of Banking  have given  clearance  to proceed with the
merger. Upon


<PAGE>

completion  of  the  Pioneer  merger,  which  is  subject  to  approval  of  the
stockholders  of NBT and  Pioneer,  LA Bank and  Pioneer  American  Bank will be
combined to form one of the largest independent  community banks in northeastern
Pennsylvania.

         On July 1, 1999, BSB Bancorp  acquired  Skaneateles  Bancorp  expanding
BSB's  presence in the Syracuse  area.  Recently BSB Bank & Trust  continued its
expansion with the addition of its ninth Broome County branch office.
         Daryl  R.  Forsythe,  president  and  chief  executive  officer  of NBT
Bancorp, will become the chairman,  president and chief executive officer of the
combined company and William C. Craine,  chairman of BSB Bancorp will become the
vice chairman of the combined  company and chairman of the executive  committee.
NBT Bank's  president and chief  operating  officer,  Martin A.  Dietrich,  will
become the president and chief operating officer of the company's New York bank.
Michael J. Chewens,  executive vice president and chief financial officer of NBT
Bancorp,  will serve as chief financial officer for the combined company.  Other
members of the executive  management  teams at NBT and BSB will retain key roles
including:  Glenn R. Small and John R.  Bradley,  executive  vice  presidents of
lending and Larry Denniston, senior vice president and corporate secretary.
         The  corporate  offices  of the  combined  company  will be  located in
Binghamton.  Other major bank  functions  will be conducted  from the  company's
Norwich, Binghamton and Scranton locations following the merger. It is estimated
that the combined company will reduce its operating expenses by approximately $7
million  annually.  Upon the full  implementation of these  aforementioned  cost
savings, the transaction is anticipated to become accretive in 2001.
         The  merger,  which  has been  unanimously  approved  by the  boards of
directors  of NBT and BSB, is subject to  standard  regulatory  and  shareholder
approvals and is expected to close in the fourth quarter of 2000.
         Daryl Forsythe commented, "This merger is a great strategic fit for NBT
and BSB. We offer similar  products and  services,  and the markets we serve are
contiguous.  By far, the most  important  common ground we have is our community
banking philosophy. Bringing these two successful companies together will create
a solid  foundation  that will  allow us to  continue  to  deliver  our brand of
banking and financial  services to our customers and communities in the years to
come."
         Thomas Thorn,  acting  president and chief  executive  officer for BSB,
stated,  "This is an  exciting  partnership  for our two  companies  that better
positions us to remain an  independent,  community-based  organization.  We will
have the  opportunity  to  continue  offering  our  customers  the high  quality
products and services  they expect  while  reaching an extended  market area and
delivering new financial services to meet the expanding needs of the customer."
         The companies  have scheduled an investor  teleconference  on April 20,
2000  at  2:00  PM  Eastern  Standard  Time.   Details  on  how  to  access  the
teleconference   can  be  obtained   by   contacting   Rebecca   Powell  at  NBT
(607-337-6516) or Stephanie Garrison at BSB (607-779-3522).
         The principal office of NBT is located in Norwich, NY. NBT is listed on
the NASDAQ under the symbol NBTB. Its principal  banking  subsidiary,  NBT Bank,
N.A.  conducts business from 36 offices in nine counties in central and northern
New York.
         The principal office of BSB is located in Binghamton, NY. BSB is listed
on the NASDAQ under the symbol BSBN. Its banking  subsidiary,  BSB Bank & Trust,
operates 22 offices in six counties in central New York and the Southern Tier.

<PAGE>


    Forward-Looking Information
    This news release contains statements regarding the projected performance of
NBT Bancorp and BSB Bancorp on a stand-alone and proforma combined basis.  These
statements  constitute  forward- looking  information  within the meaning of the
Private  Securities  Litigation  Reform Act of 1995.  Actual  results may differ
materially from the projections discussed in this release since such projections
involve  significant  risks and  uncertainties.  Factors  that might  cause such
differences  include, but are not limited to: the timing of closing the proposed
merger  being  delayed;   competitive  pressures  among  financial  institutions
increasing significantly;  economic conditions,  either nationally or locally in
areas which NBT and BSB conduct  their  operations,  being less  favorable  than
expected;  expected  cost  savings  from the  proposed  merger  not being  fully
realized  or  realized  within the  expected  time  frame;  and  legislation  or
regulatory changes which adversely affect the ability of the combined company to
conduct its current or future operations. NBT and BSB disclaim any obligation to
update any such factors or to publicly  announce the result of any  revisions to
any of the  forward-looking  statements included herein to reflect future events
or developments.
    This  document  does not  constitute  an offer of any  securities  for sale.
Before  making any decision  with respect to the  proposed  merger,  NBT and BSB
stockholders will be provided with a joint proxy statement/prospectus which will
be included in the  registration  statement to be filed with the  Securities and
Exchange  Commission by NBT. All such stockholders should read that registration
statement, including the proxy statement, before making any investment decision.

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