Exhibit 4.2


                               (FACE OF SECURITY)

            THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE
INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY
OR A NOMINEE OF A DEPOSITARY. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES
REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY
IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE, AND NO TRANSFER OF THIS
SECURITY (OTHER THAN A TRANSFER OF THIS SECURITY AS A WHOLE BY THE DEPOSITARY TO
A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY
OR ANOTHER NOMINEE OF THE DEPOSITARY) MAY BE REGISTERED EXCEPT IN LIMITED
CIRCUMSTANCES.

            UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC") TO THE ISSUER OR
ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY SECURITY
ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT HEREON IS MADE
TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL IN AS MUCH AS SINCE THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

No.1                                                  CUSIP No.:


                                 ONBANCORP, INC.

        9.25% SERIES B JUNIOR SUBORDINATED DEFERRABLE INTEREST DEBENTURE
                              DUE FEBRUARY 1, 2027

            ONBANCorp, Inc., a Delaware corporation (the "Company", which term
includes any successor Person under the Indenture hereinafter referred to), for
value received, hereby promises to pay to OnBank Capital Trust I or registered
assigns, the principal sum of sixty-one million eight hundred and fifty-six
thousand Dollars ($61,856,000) on February 1, 2027 (the "Maturity Date"), unless
previously redeemed, and to pay interest on the outstanding principal amount
hereof from February 4, 1997, or from the most recent interest payment date
(each such date, an "Interest Payment Date") to which interest has been paid or
duly provided for, semi-annually (subject to deferral as set forth herein) in
arrears on February 1 and August 1 of each year, commencing August 1, 1997, at
the rate of 9.25% per annum until the principal hereof shall have become due and
payable, and on any overdue principal and premium, if any, and (without
duplication and to the extent that payment of such interest is enforceable under
applicable law) on any overdue installment of interest at the same rate per
annum compounded semi-annually. The amount of interest payable on any Interest
Payment Date shall be computed on the basis of a 360-day year of twelve 30-day
months and, for any period less than a full calendar month, the number of days
elapsed in such month. In the event that any date on which the principal of (or
premium, if any) or interest on this Security is payable is not a Business Day,
then the payment payable on such date will be made on the next succeeding day
that is a Business Day (and without any interest or other payment in respect of
any such delay), except that if such next succeeding Business Day fall in the
next calendar year, then such payment shall be made on the immediately preceding
Business Day, in each case with the same force and effect as if made on such
date. Pursuant to the Indenture, in certain circumstances the Company will be
required to pay Additional Interest (as defined in the Indenture) with respect
to this Security. Pursuant to the Registration Rights Agreement, in certain
limited circumstances the Company will be required to pay liquidated damages (as
set forth


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in the Registration Rights Agreement) with respect to this Security.

            The interest installment so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the person in whose name this Security (or one or more Predecessor
Securities, as defined in said Indenture) is registered at the close of business
on the regular record date for such interest installment, which shall be at the
close of the business, on the fifteenth day of the month prior to the month in
which the relevant interest payment date falls. Any such interest installment
not punctually paid or duly provided for shall forthwith cease to be payable to
the holders on such regular record date and may be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on a special record date to be fixed by the Trustee for the
payment of such defaulted interest, notice whereof shall be given to the holders
of Securities not less than 10 days prior to such special record date, or may be
paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Securities may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in the Indenture.

            The principal of (and premium, if any) and interest on this Security
shall be payable at the office or agency of the Trustee maintained for that
purpose in any coin or currency of the United States of America that at the time
of payment is legal tender for payment of public and private debts; provided,
however, that, payment of interest may be made at the option of the Company by
(i) check mailed to the holder at such address as shall appear in the Security
Register or (ii) by transfer to an account maintained by the Person entitled
thereto, provided that proper written transfer instructions have been received
by the relevant record date. Notwithstanding the foregoing, so long as the
Holder of this Security is the Property Trustee, the payment of the principal of
(and premium, if any) and interest on this Security will be made at such place
and to such account as may be designated by the Property Trustee.

            The indebtedness evidenced by this Security is, to the extent
provided in the Indenture, subordinate and


                                        3


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

            This Security shall not be entitled to any benefit under the
Indenture hereinafter referred to, be valid or become obligatory for any purpose
until the Certificate of Authentication hereon shall have been signed by or on
behalf of the Trustee.


                                  4


            The provisions of this Security are continued on the reverse side
hereof and such provisions shall for all purposes have the same effect as though
fully set forth at this place.

            IN WITNESS WHEREOF, the Company has executed this certificate this
____ day of _________, 1997.

                                    OnBank Capital Trust I

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


Attest:

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

                    CERTIFICATE OF AUTHENTICATION

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

Dated: ____________, 1997

                                    THE BANK OF NEW YORK,
                                    as Trustee


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


                              (REVERSE OF SECURITY)

            This Security is one of the Securities of the Company (herein
sometimes referred to as the "Securities"), specified in the Indenture, all
issued or to be issued under and pursuant to an Indenture, dated as of February
4, 1997 (the "Indenture"), duly executed and delivered between the Company and
The Bank of New York, as Trustee (the "Trustee"), to which Indenture reference
is hereby made for a description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Company and
the holders of the Securities.

            Upon the occurrence and continuation of a Special Event prior to
February 1, 2007 (the "Initial Optional Prepayment Date"), the Company shall
have the right, at any time within 90 days following the occurrence of such
Special Event, to redeem this Security in whole (but not in part) at the Special
Event Prepayment Price. "Special Event Prepayment Price" shall mean, with
respect to any prepayment of the Securities following a Special Event, an amount
in cash equal to the greater of (i) 100% of the principal amount of the
securities to be redeemed or (ii) the sum, as determined by a Quotation Agent,
of the present values of the principal amount and premium payable with respect
to an Optional Prepayment (as defined below) of this Security on the Initial
Optional Prepayment Date, together with scheduled payments of interest on this
Security from the prepayment date to and including the Initial Optional
Prepayment Date, discounted to the prepayment date on a semi-annual basis
(assuming a 360-day year consisting of twelve 30-day months) at the Adjusted
Treasury Rate, plus, in the case of each of clauses (i) and (ii), any accrued
but unpaid interest thereon, including Compounded Interest and Additional
Interest, if any, to the date of such prepayment.

            In addition, the Company shall have the right to redeem this
Security, in whole or in part, at any time on or after the Initial Optional
Prepayment Date (an "Optional Prepayment"), at the prepayment prices set forth
below (expressed as percentages of principal to be redeemed) plus, in each case,
accrued and unpaid interest thereon (including Additional Interest and
Compounded Interest, if any) to the applicable date of prepayment (the "Optional


                                        6


Prepayment Price") if redeemed during the 12-month period beginning February 1
of the years indicated below.

                    Year                           Percentage
                    ----                           ----------

                    2007                           104.625%
                    2008                           104.163%
                    2009                           103.700%
                    2010                           103.238%
                    2011                           102.775%
                    2012                           102.313%
                    2013                           101.850%
                    2014                           101.388%
                    2015                           100.925%
                    2016                           100.463%
                    2017 and thereafter            100.000%

            The Optional Prepayment Price or the Special Event Prepayment Price,
as the case requires, shall be paid prior to 12:00 noon, New York time, on the
date of such Prepayment or at such earlier time as the Company determines,
provided, that the Company shall deposit with the Trustee an amount sufficient
to pay the applicable Prepayment Price by 10:00 a.m., New York City time, on the
date such Prepayment Price is to be paid. Any prepayment pursuant to this
paragraph will be made upon not less than 30 days nor more than 60 days notice.
If the Securities are only partially prepaid by the Company pursuant to an
Optional Prepayment, the Securities will be redeemed pro rata or by lot or by
any other method utilized by the Trustee; provided that if, at the time of
prepayment, the Securities are registered as a Global Security, the Depositary
shall determine the particular Securities to be redeemed in accordance with its
procedures.

            In the event of prepayment of this Security in part only, a new
Security or Securities for the unprepaid portion hereof will be issued in the
name of the holder hereof upon the cancellation hereof.

            Notwithstanding the foregoing, any prepayment of Securities by the
Company shall be subject to the prior approval of the Board of Governors of the
Federal Reserve System (the "Federal Reserve"), if such approval is then
required under capital guidelines or policies of the Federal Reserve.


                                        7


            In case an Event of Default, as defined in the Indenture, shall have
occurred and be continuing, the principal of all of the Securities may be
declared, and upon such declaration shall become, due and payable, in the
manner, with the effect and subject to the conditions provided in the Indenture.

            The Indenture contains provisions permitting the Company and the
Trustee, with the consent of the holders of a majority in aggregate principal
amount of the Securities at the time outstanding, as defined in the Indenture,
to execute supplemental indentures for the purpose of adding any provisions to
or changing in any manner or eliminating any of the provisions of the Indenture
or of modifying in any manner the rights of the holders of the Securities;
provided, however, that no such supplemental indenture shall, without the
consent of each holder of Securities then outstanding and affected thereby, (i)
extend the Maturity Date of any Securities, or reduce the principal amount
thereof, or reduce any amount payable on prepayment thereof, or reduce the rate
or extend the time of payment of interest thereon (subject to Article XVI of the
Indenture), or make the principal of, or interest or premium on, the Securities
payable in any coin or currency other than U.S. dollars, or impair or affect the
right of any holder of Securities to institute suit for the payment thereof, or
(ii) reduce the aforesaid percentage of Securities, the holders of which are
required to consent to any such supplemental indenture. The Indenture also
contains provisions permitting the holders of a majority in aggregate principal
amount of the Securities at the time outstanding affected thereby, on behalf of
all of the holders of the Securities, to waive any past default in the
performance of any of the covenants contained in the Indenture, or established
pursuant to the Indenture, and its consequences, except a default in the payment
of the principal of or premium, if any, or interest on any of the Securities or
a default in respect of any covenant or provision under which the Indenture
cannot be modified or amended without the consent of each holder of Securities
then outstanding. Any such consent or waiver by the holder of this Security
(unless revoked as provided in the Indenture) shall be conclusive and binding
upon such Holder and upon all future holders and owners of this Security and of
any Security issued in exchange herefor or in place hereof (whether by
registration of transfer or otherwise),


                                        8


irrespective of whether or not any notation of such consent or waiver is made
upon this Security.

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

            So long as no Event of Default shall have occurred and be
continuing, the Company shall have the right, at any time and from time to time
during the term of the Securities, to defer payments of interest by extending
the interest payment period of such Securities for a period not exceeding 10
consecutive semi-annual periods, including the first such semi-annual period
during such extension period, and not extending beyond the Maturity Date of the
Securities (an "Extended Interest Payment Period") or ending on a date other
than an Interest Payment Date, at the end of which period the Company shall pay
all interest then accrued and unpaid (together with interest thereon at the rate
specified for the Securities to the extent that payment of such interest is
enforceable under applicable law). Before the termination of any such Extended
Interest Payment Period, the Company may further defer payments of interest by
further extending such Extended Interest Payment Period, provided that such
Extended Interest Payment Period, together with all such previous and further
extensions within such Extended Interest Payment Period, (i) shall not exceed 10
consecutive semi-annual periods, including the first semi-annual period during
such Extended Interest Payment Period, (ii) shall not end on any date other than
an Interest Payment Date, and (iii) shall not extend beyond the Maturity Date of
the Securities. Upon the termination of any such Extended Interest Payment
Period and the payment of all accrued and unpaid interest and any additional
amounts then due, the Company may commence a new Extended Interest Payment
Period, subject to the foregoing requirements.

            The Company has agreed that it will not (i) declare or pay any
dividends or distributions on, or redeem, purchase, acquire, or make a
liquidation payment with respect to, any of the Company's capital stock (which
includes common and preferred stock) or (ii) make any payment of principal,
interest or premium, if any, on or


                                        9


repay or repurchase or redeem any debt securities of the Company that rank pari
passu with or junior in right of payment to the Securities or (iii) make any
guarantee payments with respect to any guarantee by the Company of the debt
securities or any Subsidiary of the Company (including any other Guarantees) if
such guarantee ranks pari passu or junior in right of payment to the Securities
(other than (a) dividends or distributions in shares of, or options, warrants or
rights to subscribe for or purchase shares of, Common Stock of the Company, (b)
any declaration of a dividend in connection with the implementation of a
stockholder's rights plan, or the issuance of stock under any such plan in the
future, or the redemption or repurchase of any such rights pursuant thereto, (c)
payments under the Series B Capital Securities Guarantee, (d) as a result of a
reclassification of the Company's capital stock or the exchange or the
conversion of one class or series of the Company's capital stock, for another
class or series of the Company's capital stock, (e) the purchase of fractional
interests in shares of the Company's capital stock pursuant to the exchange or
conversion of such capital stock or the security being exchanged or converted,
and (f) purchases of Common Stock related to the issuance of Common Stock or
rights under any of the Company's benefit plans for its directors, officers or
employees or any of the Company's dividend reinvestment plans) if at such time
(i) there shall have occurred any event of which the Company has actual
knowledge that (a) is or, with the giving of notice or the lapse of time, or
both, would be, an Event of Default and (b) in respect of which the Company
shall not have taken reasonable steps to cure, (ii) if the Securities are held
by OnBank Capital Trust, the Company shall be in default with respect to its
payment obligations under the Capital Securities Guarantee or (iii) the Company
shall have given notice of its election of the exercise of its right to extend
the interest payment period and any such extension shall be continuing.

            Subject to (i) the prior approval of the Federal Reserve if such
approval is then required under capital guidelines or policies of the Federal
Reserve, and (ii) the receipt by the Company of an opinion of counsel to the
effect that such distribution will not be a taxable event to holders of Capital
Securities, the Company will have the right at any time to liquidate the OnBank
Capital Trust and cause the Securities to be distributed to the holders of the
Trust Securities in liquidation of the Trust.


                                       10


            The Securities are issuable only in registered form without coupons
in denominations of $1,000.00 and any integral multiple thereof. As provided in
the Indenture and subject to the transfer restrictions limitations as may be
contained herein and therein from time to time, this Security is transferable by
the holder hereof on the Security Register of the Company, upon surrender of
this Security for registration of transfer at the office or agency of the
Company in the City and State of New York accompanied by a written instrument or
instruments of transfer in form satisfactory to the Company or the Trustee duly
executed by the holder hereof or his attorney duly authorized in writing, and
thereupon one or more new Securities of authorized denominations and for the
same aggregate principal amount and series will be issued to the designated
transferee or transferees. No service charge will be made for any such transfer,
but the Company may require payment of a sum sufficient to cover any tax or
other governmental charge payable in relation thereto.

            Prior to due presentment for registration of transfer of this
Security, the Company, the Trustee, any authenticating agent, any paying agent,
any transfer agent and the registrar may deem and treat the holder hereof as the
absolute owner hereof (whether or not this Security shall be overdue and
notwithstanding any notice of ownership or writing hereon made by anyone other
than the Security Registrar) for the purpose of receiving payment of or on
account of the principal hereof and premium, if any, and (subject to the
Indenture) interest due hereon and for all other purposes, and neither the
Company nor the Trustee nor any authenticating agent nor any paying agent nor
any transfer agent nor any registrar shall be affected by any notice to the
contrary.

            No recourse shall be had for the payment of the principal of or
premium, if any, or interest on this Security, or for any claim based hereon, or
otherwise in respect hereof, or based on or in respect of the Indenture, against
any incorporator, stockholder, officer or director, past, present or future, as
such, of the Company or of any predecessor or successor Person, whether by
virtue of any constitution, statute or rule of law, or by the enforcement of any
assessment or penalty or otherwise, all such liability being, by the acceptance
hereof and as part of the consideration for the issuance hereof, expressly
waived and released.


                                       11


            All terms used in this Security that are defined in the Indenture
shall have the meanings assigned to them in the Indenture.

            THE INDENTURE AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO CONFLICT
OF LAW PROVISIONS THEREOF.


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