<PAGE>

                                                                     EXHIBIT 4.2

         THIS SECURITY IS NOT A DEPOSIT AND IS NOT INSURED BY THE FEDERAL
DEPOSIT INSURANCE CORPORATION OR ANY FEDERAL OR OTHER GOVERNMENTAL AGENCY.

         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 THEREOF. THIS SECURITY MAY NOT BE TRANSFERRED TO, OR REGISTERED OR
EXCHANGED FOR SECURITIES REGISTERED IN THE NAME OF, ANY PERSON OTHER THAN THE
DEPOSITARY OR A NOMINEE THEREOF OR A SUCCESSOR OF SUCH DEPOSITARY OR A NOMINEE
OF SUCH SUCCESSOR, AND NO SUCH TRANSFER MAY BE REGISTERED, EXCEPT IN THE LIMITED
CIRCUMSTANCES DESCRIBED IN THE INDENTURE. EVERY SECURITY AUTHENTICATED AND
DELIVERED UPON REGISTRATION OF TRANSFER OF, OR IN EXCHANGE FOR OR IN LIEU OF,
THIS SECURITY SHALL BE A GLOBAL SECURITY SUBJECT TO THE FOREGOING, EXCEPT IN
SUCH LIMITED CIRCUMSTANCES.

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) TO THE
COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER NAME AS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND
ANY PAYMENT HEREON MADE TO CEDE & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF
FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                              COMERICA INCORPORATED

                    4.80% Subordinated Notes due May 1, 2015

No. R-1                                                           US$300,000,000
CUSIP No.  200340 AL 1

         Comerica Incorporated, a corporation duly organized and existing under
the laws of the State of Delaware (herein called the "Company", which term
includes any successor Person under the Indenture hereinafter referred to), for
value received, hereby promises to pay to CEDE & CO., or registered assigns, the
principal sum of THREE HUNDRED MILLION DOLLARS (US$300,000,000) on May 1, 2015,
and to pay interest thereon from May 6, 2003 or from the most recent Interest
Payment Date to which interest has been paid or duly provided for, semi-annually
on May 1 and November 1 in each year, commencing November 1, 2003, at the rate
of 4.80% per annum, until the principal hereof is paid or made available for
payment. The interest so payable, and punctually paid or duly provided for, on
any Interest Payment Date will, as provided in such Indenture, be paid to the
Person in whose name this Security (or one or more Predecessor Securities) is
registered at the close of business on the Regular Record Date for such
interest, which shall be the April 15 or October 15 (whether or not a Business
Day), as the case may be, next preceding such Interest Payment Date. Any such
interest not so punctually paid or duly provided for will forthwith cease to be
payable to the Holder on such Regular Record Date and may either be paid to the
Person in whose name this Security (or one or more Predecessor Securities) is
registered at the close of business on a Special Record Date for the payment of
such Defaulted Interest to be fixed by the Trustee, notice whereof shall be
given to Holders of Securities of this series not less than 10 days prior to
such Special Record Date, or be paid at any


<PAGE>

time in any other lawful manner not inconsistent with the requirements of any
securities exchange on which the Securities of this series may be listed, and
upon such notice as may be required by such exchange, all as more fully provided
in said Indenture.

         Payment of the principal of (and premium, if any) and interest on this
Security will be made at the office or agency of the Company maintained for that
purpose in the City of New York, in such coin or currency of the United States
of America as at the time of payment is legal tender for payment of public and
private debts; provided, however, that at the option of the Company payment of
interest may be made by check mailed to the address of the Person entitled
thereto as such address shall appear in the Security Register.

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

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

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

         Dated:  May 6, 2003

                                     COMERICA INCORPORATED


                                     By:
                                        ----------------------------------------
                                           Ronald D. Marks
                                           Senior Vice President and Treasurer



         Attest:

         -------------------------
         Mark Yonkman
         Senior Vice President, Assistant Secretary
         and General Counsel - Investment Bank and Corporate Finance


<PAGE>

                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

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

                                   JPMORGAN CHASE BANK
                                   As Trustee



                                   By:
                                      ------------------------------------------
                                                     Authorized Signer



<PAGE>

                              [REVERSE OF SECURITY]

         This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities") issued and to be issued in one or more
series under a subordinated debt indenture, dated as of May 1, 2003 (herein
called the "Indenture"), between the Company and JPMorgan Chase Bank, as trustee
(herein called the "Trustee", which term includes any successor trustee under
the Indenture), to which Indenture and all indentures supplemental thereto
reference is hereby made for a statement of the respective rights, limitations
of rights, duties and immunities thereunder of the Company, the Trustee, the
holders of Senior Indebtedness, Entitled Persons and the Holders of the
Securities and of the terms upon which the Securities are, and are to be,
authenticated and delivered. This Security is one of the series designated on
the face hereof and will initially be offered in the principal amount of
$300,000,000. The Company may, without the consent of the Holders, issue
additional Securities and thereby increase such principal amount in the future,
on the same terms and conditions and with the same CUSIP number as this
Security.

         The Security is not subject to redemption prior to maturity.

         The Indenture contains provisions for defeasance at any time of (a) the
entire indebtedness evidenced by this Security and (b) certain restrictive
covenants, in each case upon compliance by the Company with certain conditions
set forth therein, which provisions apply to this Security.

         The indebtedness evidenced by this Security is, to the extent provided
in the Indenture, subordinate and subject 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. This Security is also
issued subordinate and subject to the provisions of the Indenture regarding
prior payment in full to Entitled Persons in respect of Other Financial
Obligations. The Indenture also provides that if, upon the occurrence of certain
events of bankruptcy or insolvency relating to the Company, there remains, after
giving effect to such subordination provisions, any amount of cash, property or
securities available for payment or distribution in respect of Securities of
this series ( "Excess Proceeds"), and if, at such time, any Entitled Person has
not received payment in full of all amounts due or to become due on or in
respect of Other Financial Obligations, then such Excess Proceeds shall first be
applied to pay or provide for the payment in full of such Other Financial
Obligations before any payment or distribution may be made in respect of
Securities of this series. Each Holder of this Security, by accepting the same,
(a) agrees to and shall be bound by such provisions, (b) authorizes and directs
the Trustee on his behalf to take such action as may be necessary or appropriate
to effectuate the subordination and payment of Excess Proceeds as provided in
the Indenture and (c) appoints the Trustee his attorney-in-fact for any and all
such purposes.

         The principal of this Security may not be declared due and payable upon
the occurrence of an Event of Default, except an Event of Default relating to
certain events involving the bankruptcy, insolvency or reorganization of the
Company. If an Event of Default with respect to Securities of this series
relating to certain events involving the bankruptcy, insolvency or
reorganization of the Company shall occur and be continuing, the principal of
the Securities of


<PAGE>

this series may be declared due and payable in the manner and with the effect
provided in the Indenture.

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

         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 any premium and
interest on this Security at the times, place and rate, and in the coin or
currency, herein prescribed.

         As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for registration of transfer at the
office or agency of the Company in any place where the principal of and any
premium and interest on this Security are payable, duly endorsed by, or
accompanied by a written instrument of transfer in form satisfactory to the
Company and the Security Registrar duly executed by, the Holder hereof or his
attorney duly authorized in writing, and thereupon one or more new Securities of
this series and of like tenor, of authorized denominations and for the same
aggregate principal amount, will be issued to the designated transferee or
transferees.

         The Securities of this series are issuable only in registered form
without coupons in denominations of $1,000 and any integral multiple of $1,000
in excess thereof. As provided in the Indenture and subject to certain
limitations therein set forth, Securities of this series are exchangeable for a
like aggregate principal amount of Securities of this series and of like tenor
of a different authorized denomination, as requested by the Holder surrendering
the same.

         No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Security for registration of transfer,
the Company, the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not this Security be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

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



<PAGE>


                                   ASSIGNMENT


FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s)
unto

PLEASE INSERT SOCIAL SECURITY OR
OTHER IDENTIFYING NUMBER OF ASSIGNEE

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


--------------------------------------------------------------------------------
PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE OF ASSIGNEE


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

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

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

the within Security and all rights thereunder, hereby irrevocably constituting
and appointing __________________________________ attorney to transfer said
Security on the books of the Company, with full power of substitution in the
premises.

Dated:   _______________________________

Signature: ____________________________

         NOTICE: THE SIGNATURE TO THIS ASSIGNMENT MUST CORRESPOND WITH THE NAME
AS WRITTEN UPON PAGE 1 OF THE WITHIN INSTRUMENT IN EVERY PARTICULAR, WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATEVER.