<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            WESTBANK CORPORATION
             (Exact name of issuer as specified in its charter)
        Massachusetts                                            04-2830731
(State or other jurisdiction                                  (I.R.S. Employer
      of incorporation)                                      Identification No.)

                                 225 Park Avenue
                   West Springfield, Massachusetts 01090-0149
              (Address of principal executive offices and zip code)

                  CARGILL BANK OF CONNECTICUT STOCK OPTION PLAN
                            DATED SEPTEMBER 21, 1992
                       AS ASSUMED BY WESTBANK CORPORATION
                            (Full title of the Plan)

                            John M. Lilly, Treasurer
                              Westbank Corporation
                                 225 Park Avenue
                   West Springfield, Massachusetts 01090-0149
                            Telephone: (413) 747-1400
                     (Name and address of Agent for Service)
                                    Copy to:
                             W. Garth Janes, Esquire
                  Doherty, Wallace, Pillsbury and Murphy, P.C.
                          One Monarch Place, 19th Floor
                     Main Street, Springfield, MA 01144-1002

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
Title of                           Proposed       Proposed
Securities                          Maximum       Maximum
  to be             Amount         Offering      Aggregate
Amount of            to be         Price Per      Offering
Registered        Registered        Share(1)        Price      Registration Fee
<S>               <C>              <C>          <C>            <C>
Common Stock        54,885           $4.02      $220,637.70          $20.30
</TABLE>

--------
1 Calculated pursuant to Rule 457 (h) of the Securities Act of 1993, as amended,
based on the exercise price of the options issued under the Plan.


                                       1
<PAGE>
                                     PART II
             INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

The following documents filed by the Company with the Commission are
incorporated by reference and shall be deemed to be a part hereof:

      1.    The Company's Quarterly Report on Form 10-Q for the quarter ended
            March 31, 2002.

      2.    The Company's Annual Report on Form 10-K for the year ended
            December 31, 2001.

      3.    The Company's Proxy Statement dated March 15, 2002 for the Annual
            Meeting of Shareholders held on April 17, 2002.

Documents filed by the Company with the Commission pursuant to Section 13(a),
13(c), 14, and 15(d) of the 1934 Act subsequent to the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all the securities offered hereby have been sold or which deregisters all
of the securities remaining unsold shall be deemed to be incorporated by
reference into this Registration Statement and to be part hereof from the date
of filing of such documents. Any statement contained in a document incorporated
by reference herein shall be deemed to be modified or superseded for all
purposes to the extent that a statement contained herein or in any other
document which also is incorporated herein by reference modifies or replaces
such statement. Any such statement as modified or superseded shall not be
deemed, except as modified or superseded, to constitute a part of this
Registration Statement.

ITEM 4.  DESCRIPTION OF SECURITIES.

Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

In general, Article V, Section 9 of the Company's By-Laws provides for
indemnification of each director, officer, employee or agent of the Company, any
former director, officer, employee or agent of the Company, and any person who
is or shall be a director, officer, employee or agent of another organization in
which the Company owns shares or of which it is a creditor, against all
liabilities and expenses reasonably incurred by such person in connection with,
or arising out of, any action, suit or proceeding in which such person may be a
party defendant or with which he may be threatened or otherwise involved,
directly or indirectly, by reason of his being or having


                                       2
<PAGE>
been a director or officer of the Company or such other organization, except in
relation to matters as to which such person shall be finally adjudged (other
than by consent) in such action, suit or proceeding not to have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the Company or such other organization, and, with respect to any
criminal action or proceeding, only to the extent that he had no reasonable
cause to believe his conduct was unlawful.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

Not applicable.

ITEM 8.  EXHIBITS.

See Exhibit Index.

ITEM 9.  UNDERTAKINGS.

(a)   The undersigned Registrant hereby undertakes:

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

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

            (ii)  To reflect in the prospectus any fact or events arising after
                  the effective date of the Registration Statement (or most
                  recent post-effective amendment thereof) which, individually
                  or in the aggregate, represent a fundamental change in the
                  information set forth in the Registration Statement; and

            (iii) To include any material information with respect to the plan
                  of distribution not previously disclosed in the Registration
                  Statement or any material change to such information in the
                  Registration Statement:

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

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


                                       4
<PAGE>
      (3)   To remove from registration by means of a post-effective amendment
            any of the securities being registered which remain unsold at the
            consummation of the offering.

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

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


                                       4
<PAGE>
                                   SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of West Springfield, Commonwealth of Massachusetts, July
17, 2002.


                                 WESTBANK CORPORATION


                                 By:   /s/
                                       ------------------------------------
                                       Donald R. Chase, President


                                       5
<PAGE>
                                POWER OF ATTORNEY

We, the undersigned Directors and Officers of Westbank Corporation, do hereby
severally constitute and appoint Donald R. Chase and John M. Lilly, or either of
them, our true and lawful attorneys and agents, to do any and all acts and
things in our name and behalf in our capacities as Directors and Officers and
execute any and all instruments for us in our name in the capacities indicated
below, which said attorneys and agents, or either of them, may deem necessary or
advisable to enable said Corporation to comply with the Securities Act of 1933,
as amended and adjusted, and any rules, regulations, and requirements of the
Securities and Exchange Commission, in connection with this Registration
Statement on Form S-8 including specifically but without limitation, power and
authority to sign for us or any of us, in our names in the capacities listed
below, any and all amendments (including post-effective amendments) hereto; and
we do each hereby ratify and confirm all that said attorneys and agents, or
either one of them, shall do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended and
adjusted, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated.

     Signatures                        Title
Date


/s/                           President, Chief                    July 17, 2002
------------------------      Executive Officer
Donald R. Chase                and Director
                              (Principal Executive
                              Officer)


/s/                           Treasurer and Chief                 July 17, 2002
------------------------      Financial Officer
John M. Lilly                 (Principal Financial
                              and Accounting Officer)


/s/                           Director                            July 17, 2002
------------------------
Roland O. Archambault


/s/                           Director                            July 17, 2002
------------------------
Mark A. Beauregard


/s/                           Director                            July 17, 2002
------------------------
David R. Chamberland


                                        6
<PAGE>
/s/                           Director and                        July 17, 2002
------------------------      Chairman of the Board
Ernest N. Laflamme, Jr.


/s/                           Director                            July 17, 2002
------------------------
G. Wayne McCary


/s/                           Director and Clerk                  July 17, 2002
------------------------
Robert J. Perlak


                              Director                            July 17, 2002
------------------------
George R. Sullivan


/s/                           Director                            July 17, 2002
------------------------
James E. Tremble


                                       7
<PAGE>
                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
Number                            Exhibit                                Page
<S>              <C>                                                     <C>
  5              Opinion of Doherty, Wallace, Pillsbury
                 and Murphy, P.C.

 23(a)           Consent of Deloitte & Touche LLP

 23(b)           Consent of Doherty, Wallace, Pillsbury
                 and Murphy, P.C. (included in Exhibit 5)

 24              Power of Attorney (included on signature
                 page hereof)

 99              Cargill Bank of Connecticut Stock Option Plan
                 dated September 21, 1992, as assumed by Westbank
                 Corporation
</TABLE>


                                       8
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{"company-data": {"conformed-name": "WESTBANK CORP", "cik": "0000742070", "assigned-sic": "6022", "irs-number": "042830731", "state-of-incorporation": "MA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-96943", "film-number": "02708309"}, "business-address": {"street1": "225 PARK AVE", "street2": "PO BOX 149", "city": "WEST SPRINGFIELD", "state": "MA", "zip": "01090-0149", "phone": "4137471400"}, "mail-address": {"street1": "225 PARK AVE P O BOX 149", "street2": "225 PARK AVE P O BOX 149", "city": "WEST SPRINGFIELD", "state": "MA", "zip": "01090-0149"}}
SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                            WESTBANK CORPORATION
             (Exact name of issuer as specified in its charter)
        Massachusetts                                            04-2830731
(State or other jurisdiction                                  (I.R.S. Employer
      of incorporation)                                      Identification No.)

                                 225 Park Avenue
                   West Springfield, Massachusetts 01090-0149
              (Address of principal executive offices and zip code)

                  CARGILL BANK OF CONNECTICUT STOCK OPTION PLAN
                            DATED SEPTEMBER 21, 1992
                       AS ASSUMED BY WESTBANK CORPORATION
                            (Full title of the Plan)

                            John M. Lilly, Treasurer
                              Westbank Corporation
                                 225 Park Avenue
                   West Springfield, Massachusetts 01090-0149
                            Telephone: (413) 747-1400
                     (Name and address of Agent for Service)
                                    Copy to:
                             W. Garth Janes, Esquire
                  Doherty, Wallace, Pillsbury and Murphy, P.C.
                          One Monarch Place, 19th Floor
                     Main Street, Springfield, MA 01144-1002

                         CALCULATION OF REGISTRATION FEE
Title of                           Proposed       Proposed
Securities                          Maximum       Maximum
  to be             Amount         Offering      Aggregate
Amount of            to be         Price Per      Offering
Registered        Registered        Share(1)        Price      Registration Fee
Common Stock        54,885           $4.02      $220,637.70          $20.30
--------
1 Calculated pursuant to Rule 457 (h) of the Securities Act of 1993, as amended,
based on the exercise price of the options issued under the Plan.

                                       1
PART II
             INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

The following documents filed by the Company with the Commission are
incorporated by reference and shall be deemed to be a part hereof:

      1.    The Company's Quarterly Report on Form 10-Q for the quarter ended
            March 31, 2002.

      2.    The Company's Annual Report on Form 10-K for the year ended
            December 31, 2001.

      3.    The Company's Proxy Statement dated March 15, 2002 for the Annual
            Meeting of Shareholders held on April 17, 2002.

Documents filed by the Company with the Commission pursuant to Section 13(a),
13(c), 14, and 15(d) of the 1934 Act subsequent to the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all the securities offered hereby have been sold or which deregisters all
of the securities remaining unsold shall be deemed to be incorporated by
reference into this Registration Statement and to be part hereof from the date
of filing of such documents. Any statement contained in a document incorporated
by reference herein shall be deemed to be modified or superseded for all
purposes to the extent that a statement contained herein or in any other
document which also is incorporated herein by reference modifies or replaces
such statement. Any such statement as modified or superseded shall not be
deemed, except as modified or superseded, to constitute a part of this
Registration Statement.

ITEM 4.  DESCRIPTION OF SECURITIES.

Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

In general, Article V, Section 9 of the Company's By-Laws provides for
indemnification of each director, officer, employee or agent of the Company, any
former director, officer, employee or agent of the Company, and any person who
is or shall be a director, officer, employee or agent of another organization in
which the Company owns shares or of which it is a creditor, against all
liabilities and expenses reasonably incurred by such person in connection with,
or arising out of, any action, suit or proceeding in which such person may be a
party defendant or with which he may be threatened or otherwise involved,
directly or indirectly, by reason of his being or having

                                       2
been a director or officer of the Company or such other organization, except in
relation to matters as to which such person shall be finally adjudged (other
than by consent) in such action, suit or proceeding not to have acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the Company or such other organization, and, with respect to any
criminal action or proceeding, only to the extent that he had no reasonable
cause to believe his conduct was unlawful.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

Not applicable.

ITEM 8.  EXHIBITS.

See Exhibit Index.

ITEM 9.  UNDERTAKINGS.

(a)   The undersigned Registrant hereby undertakes:

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

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

            (ii)  To reflect in the prospectus any fact or events arising after
                  the effective date of the Registration Statement (or most
                  recent post-effective amendment thereof) which, individually
                  or in the aggregate, represent a fundamental change in the
                  information set forth in the Registration Statement; and

            (iii) To include any material information with respect to the plan
                  of distribution not previously disclosed in the Registration
                  Statement or any material change to such information in the
                  Registration Statement:

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

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

                                       4
(3)   To remove from registration by means of a post-effective amendment
            any of the securities being registered which remain unsold at the
            consummation of the offering.

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

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

                                       4
SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the Town of West Springfield, Commonwealth of Massachusetts, July
17, 2002.

                                 WESTBANK CORPORATION

                                 By:   /s/
                                       ------------------------------------
                                       Donald R. Chase, President

                                       5
POWER OF ATTORNEY

We, the undersigned Directors and Officers of Westbank Corporation, do hereby
severally constitute and appoint Donald R. Chase and John M. Lilly, or either of
them, our true and lawful attorneys and agents, to do any and all acts and
things in our name and behalf in our capacities as Directors and Officers and
execute any and all instruments for us in our name in the capacities indicated
below, which said attorneys and agents, or either of them, may deem necessary or
advisable to enable said Corporation to comply with the Securities Act of 1933,
as amended and adjusted, and any rules, regulations, and requirements of the
Securities and Exchange Commission, in connection with this Registration
Statement on Form S-8 including specifically but without limitation, power and
authority to sign for us or any of us, in our names in the capacities listed
below, any and all amendments (including post-effective amendments) hereto; and
we do each hereby ratify and confirm all that said attorneys and agents, or
either one of them, shall do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended and
adjusted, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated.

     Signatures                        Title
Date

/s/                           President, Chief                    July 17, 2002
------------------------      Executive Officer
Donald R. Chase                and Director
                              (Principal Executive
                              Officer)

/s/                           Treasurer and Chief                 July 17, 2002
------------------------      Financial Officer
John M. Lilly                 (Principal Financial
                              and Accounting Officer)

/s/                           Director                            July 17, 2002
------------------------
Roland O. Archambault

/s/                           Director                            July 17, 2002
------------------------
Mark A. Beauregard

/s/                           Director                            July 17, 2002
------------------------
David R. Chamberland

                                        6
/s/                           Director and                        July 17, 2002
------------------------      Chairman of the Board
Ernest N. Laflamme, Jr.

/s/                           Director                            July 17, 2002
------------------------
G. Wayne McCary

/s/                           Director and Clerk                  July 17, 2002
------------------------
Robert J. Perlak

                              Director                            July 17, 2002
------------------------
George R. Sullivan

/s/                           Director                            July 17, 2002
------------------------
James E. Tremble

                                       7
EXHIBIT INDEX
Number                            Exhibit                                Page
5              Opinion of Doherty, Wallace, Pillsbury
                 and Murphy, P.C.

 23(a)           Consent of Deloitte & Touche LLP

 23(b)           Consent of Doherty, Wallace, Pillsbury
                 and Murphy, P.C. (included in Exhibit 5)

 24              Power of Attorney (included on signature
                 page hereof)

 99              Cargill Bank of Connecticut Stock Option Plan
                 dated September 21, 1992, as assumed by Westbank
                 Corporation
8