COMMONWEALTH EDISON COMPANY


                                       and


                                 CITIBANK, N.A.

              Trustee Under Indenture Dated as of September 1, 1987
                           as amended and supplemented







              Supplemental Indenture Dated as of September 20, 2000

                            Providing for Issuance of

                Floating Rate Senior Notes due September 30, 2002
                Floating Rate Senior Notes due September 30, 2003



                                       1


<PAGE>
          THIS SUPPLEMENTAL INDENTURE, dated as of the 20th day of September,
2000, between COMMONWEALTH EDISON COMPANY, a corporation duly organized and
validly existing under the laws of the State of Illinois (hereinafter called the
"Company"), and CITIBANK, N.A., a national banking association incorporated and
existing under the laws of the United States of America (hereinafter called the
"Trustee"), Trustee under the Indenture dated as of September 1, 1987, as
amended and supplemented, between the Company and the Trustee (said Indenture,
as heretofore amended and supplemented, hereinafter called the "Original
Indenture").

                              W I T N E S S E T H:

          WHEREAS, the Original Indenture provides for the issuance from time to
time thereunder, in series, of Notes of the Company to provide funds for its
corporate purposes; and

          WHEREAS, the Company desires, by this Supplemental Indenture, to
create (i) a series of Notes to be issuable under the Original Indenture and to
be known as the Company's Floating Rate Senior Notes due September 30, 2002
(hereinafter called the "2002 Notes") and (ii) a series of notes to be issuable
under the Original Indenture and to be known as the Company's Floating Rate
Senior Notes due September 30, 2003 (hereinafter called the "2003 Notes"); and
the terms and provisions of such 2002 Notes and 2003 Notes (collectively
referred to herein as the "Senior Notes") to be as hereinafter set forth; and

          WHEREAS, all things necessary to make the Senior Notes, when executed
by the Company and authenticated and delivered by the Trustee and duly issued by
the Company, the valid obligations of the Company, and to make this Supplemental
Indenture a valid agreement of the Company, in accordance with their and its
terms, have been done.

          NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

          For and in consideration of the premises and the purchase of the
Senior Notes by the Holders thereof, it is mutually covenanted and agreed, for
the equal and proportionate benefit of such Holders, as follows:

          Section 1. Defined Terms. All terms used in this Supplemental
Indenture that are defined in the Original Indenture have the meanings assigned
to them in the Original Indenture.

          Section 2. Designation and Terms of the 2002 Notes. (a) A series of
Notes created by this Supplemental Indenture shall be known and designated as
the "Floating Rate Senior Notes due September 30, 2002" of the Company and shall
be limited in aggregate principal amount to $200,000,000.00. The 2002 Notes
shall be issued in substantially the form thereof attached as Exhibit A to this
Supplemental Indenture.

          The Stated Maturity of the 2002 Notes shall be September 30, 2002. The
2002 Notes shall bear interest as provided in the form thereof attached as
Exhibit A to this Supplemental Indenture.

                                       2
<PAGE>
          (b) Payment of principal of the 2002 Notes and, unless otherwise paid
as hereinafter provided, the interest thereon will be made at the office or
agency of the Company in the Borough of Manhattan, City and State of New York,
provided, however, that payment of interest may be made at the option of the
Company by check or draft mailed to the person entitled thereto at his address
appearing in the Note Register.

          Section 3. Designation and Terms of the 2003 Notes. (a) A series of
Notes created by this Supplemental Indenture shall be known and designated as
the "Floating Rate Senior Notes due September 30, 2003" of the Company and shall
be limited in aggregate principal amount to $250,000,000.00. The 2003 Notes
shall be issued in substantially the form thereof attached as Exhibit B to this
Supplemental Indenture.

          The Stated Maturity of the 2003 Notes shall be September 30, 2003. The
2003 Notes shall bear interest as provided in the form thereof attached as
Exhibit B to this Supplemental Indenture.

          (b) Payment of principal of the 2003 Notes and, unless otherwise paid
as hereinafter provided, the interest thereon will be made at the office or
agency of the Company in the Borough of Manhattan, City and State of New York,
provided, however, that payment of interest may be made at the option of the
Company by check or draft mailed to the person entitled thereto at his address
appearing in the Note Register.

          Section 4. Issuance of Senior Notes. (a) The Senior Notes may be
issued in denominations of $100,000 and in integral multiples of $10,000 in
excess thereof.

          (b) Upon the execution of this Supplemental Indenture, the Senior
Notes may be executed by the Company and delivered to the Trustee for
authentication, and the Trustee shall, upon receipt of the documents specified
in Section 2.02 of the Original Indenture, thereupon authenticate and deliver
said Senior Notes to or upon a Company Order.

          Section 5. Redemption of Senior Notes. The Senior Notes will not be
redeemable prior to September 30, 2001; and thereafter may be redeemed at the
option of the Company, in whole or in part, beginning on September 30, 2001 and
on the last Business Day of each calendar month thereafter, at a redemption
price equal to 100% of the principal amount to be redeemed plus accrued and
unpaid interest on such Senior Notes to the date of redemption. In order to
redeem any such Senior Notes, the Company will give not less than 30 nor more
than 60 days prior notice mailed to each registered holder of the Senior Notes
to be redeemed at its registered address by first-class mail.

          Section 6. Depository System. The Senior Notes intially will be issued
pursuant to Section 4(2) of the Securities Act of 1933, as amended (the
"Securities Act"), as Depository Notes registered in the name of Cede & Co. (as
nominee for The Depository Trust Company ("DTC"), New York, New York). The
Senior Notes issued as Depository Notes shall bear the depository legend in
substantially the form set forth in Exhibits A and B, as applicable. The Senior
Notes will contain restrictions on transfer, substantially as described in the
respective forms thereof set forth in Exhibits A and B hereto. Each Senior Note,
whether issued as a Depository Note or in a certificated form, shall bear the
non-registration legend in substantially

                                       3
<PAGE>
the form set forth in the applicable form of Senior Note, unless otherwise
agreed by the Company, such agreement to be confirmed in writing to the Trustee.
Nothing in this Supplemental Indenture shall be construed to require the Company
to register any Senior Notes under the Securities Act, unless otherwise
expressly agreed by the Company, confirmed in writing to the Trustee, or to make
any transfer of any Senior Note in violation of applicable law.

          It is contemplated that beneficial interests in the Senior Notes owned
by qualified institutional buyers (as defined in Rule 144A under the Securities
Act) ("QIBs") or sold to QIBs in reliance upon Rule 144A under the Securites Act
will be represented by one or more separate Depository Notes registered in the
name of Cede & Co., as registered owner and as nominee for DTC; beneficial
interests in Senior Notes sold to foreign purchasers pursuant to Regulation S
under the Securities Act will be evidenced by one or more Depository Notes (each
a "Regulation S Depository Note") and will be registered in the name of Cede &
Co., as registered owner and as nominee for DTC for the accounts of Euroclear
and Clearstream Banking, societe anonyme ("Clearstream Luxembourg"); prior to
the 40th day after the initial issuance of the Senior Notes, beneficial
interests in a Regulation S Depository Note may be held only through Euroclear
or Clearstream Luxembourg; Senior Notes acquired by institutional "accredited
investors" (as defined in Rule 501(a)(1), (2), (3) or (7) under the Securities
Act) ("IAIs") and other eligible transferees, who are not QIBs and who are not
foreign purchasers pursuant to Regulation S under the Securities Act, will be in
certificated form.

          With respect to Notes registered in the name of DTC or its nominee,
the Company and the Trustee shall have no responsibility or obligation to any
broker-dealer, bank or other financial institution for which DTC holds such
notes from time to time as securities depository (each such broker-dealer, bank
or other financial institution being referred to herein as a "Depository
Participant") or to any person on behalf of whom such a Depository Participant
holds an interest in such notes (each such person being herein referred to as an
"Indirect Participant"). Without limiting the immediately preceding sentence,
the Company and the Trustee shall have no responsibility or obligation with
respect to (a) the accuracy of the records of DTC, its nominee or any Depository
Participant with respect to any ownership interest in the Notes, (b) the
delivery to any Depository Participant or any Indirect Participant or any other
person, other than a registered owner of a Note, of any notice with respect to
the Notes, (c) the payment to any Depository Participant or Indirect Participant
or any other person, other than a registered owner of a Note, of any amount with
respect to principal of, or interest on, the Notes, or (d) any consent given by
DTC as registered owner. So long as certificates for the Notes of a particular
series of Senior Notes are not issued, the Company and the Trustee may treat DTC
or any successor securities depository as, and deem DTC or any successor
securities depository to be, the absolute owner of such Notes for all purposes
whatsoever, including without limitation (i) the payment of principal and
interest on such Notes, (ii) giving notice of matters with respect to such Notes
and (iii) registering transfers with respect to such Notes.

          Notwithstanding any other provision of the Original Indenture to the
contrary, so long as any Note is registered in the name of DTC or its nominee,
all payments with respect to principal of and interest on such Note and all
notices with respect to such Note shall be made and given, respectively, in the
manner provided in the Representation Letter regarding the Senior Notes executed
by the Trustee, the Company and DTC.

                                       4
<PAGE>
                              T E S T I M O N I U M

          This Supplemental Indenture may be executed in any number of
counterparts, each of which so executed shall be deemed to be an original, but
all such counterparts shall together constitute but one and the same instrument.


          IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the day and year first
above written.

                                       COMMONWEALTH EDISON COMPANY


                                       By:/s/ Patricia L. Kampling
                                          ------------------------
                                          Patricia L. Kampling
                                          Treasurer

ATTEST:


/s/ John P. McGarrity
---------------------
John P. McGarrity
Secretary



                                       CITIBANK, N.A.


                                       By:/s/ P. DeFelice
                                          ---------------
                                          Name:  P. DeFelice
                                          Title:  Vice President

ATTEST:


/s/ Nancy Forte
---------------
Name:  Nancy Forte
Title:  Senior Trust Officer


                                       5
<PAGE>
                                                                       EXHIBIT A

            Form of Floating Rate Senior Note Due September 30, 2002
            --------------------------------------------------------

                               [depository legend]

          Unless this Certificate is presented by an authorized representative
of The Depository Trust Company, a New York corporation ("DTC"), 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 in such other name
as is requested by an authorized representative of DTC (and any payment 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 inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

                            [non-registration legend]

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS SECURITY,
AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE RESOLD,
PLEDGED OR OTHERWISE TRANSFERRED OTHER THAN (A) (1) TO THE COMPANY, (2) IN A
TRANSACTION ENTITLED TO AN EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144
UNDER THE SECURITIES ACT, (3) SO LONG AS THIS SECURITY IS ELIGIBLE FOR RESALE
PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE 144A"), TO A PERSON WHOM
THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE
MEANING OF RULE 144A PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A
QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR
OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A (AS INDICATED BY THE BOX
CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS
SECURITY), (4) IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 OF
REGULATION S UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY), (5)
TO AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1),
(2), (3) OR (7) UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY) THAT
IS ACQUIRING THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION, AND
A CERTIFICATE IN THE FORM ATTACHED TO THIS SECURITY IS DELIVERED BY THE
TRANSFEREE TO THE COMPANY AND THE TRUSTEE OR (6) IN ACCORDANCE WITH ANOTHER
APPLICABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT
(AND BASED UPON AN OPINION OF COUNSEL ACCEPTABLE TO THE COMPANY) AND (B) IN EACH
CASE IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF EACH STATE OF THE
UNITED STATES. AN INSTITUTIONAL ACCREDITED INVESTOR HOLDING THIS SECURITY AGREES
IT WILL FURNISH TO THE COMPANY AND THE TRUSTEE SUCH CERTIFICATES AND OTHER
INFORMATION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY TRANSFER BY IT OF
THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. tHE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A
OR (2) AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE
501(A)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT AND THAT IT IS HOLDING THIS
SECURITY FOR INVESTMENT PURPOSES AND NOT FOR


<PAGE>
DISTRIBUTION OR (3) A NON-u.S. PERSON OUTSIDE THE UNITED STATES WITHIN THE
MEANING OF, OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH (o)(2) OF
RULE 902 UNDER, REGULATION S UNDER THE SECURITIES ACT.


No. R-__                                                          Cusip No.  ___

                               [FACE OF 2002 NOTE]

                           COMMONWEALTH EDISON COMPANY

                FLOATING RATE SENIOR NOTE DUE SEPTEMBER 30, 2002

          COMMONWEALTH EDISON COMPANY, a corporation duly organized and existing
under the laws of the State of Illinois (herein referred to as the "Company",
which term includes any successor corporation under the Indenture), for value
received, hereby promises to pay to



or registered assigns, the principal sum of _________________________ Dollars
($_________) on September 30, 2002, and to pay interest on said principal sum
quarterly on March 30, June 30, September 30 and December 30 of each year,
commencing December 30, 2000 (each an "Interest Payment Date") at the per annum
interest rate determined by the Calculation Agent on each Interest Determination
Date, as such terms are defined herein, until the principal hereof is paid or
made available for payment. Interest on the Notes of this series will accrue
from September 21, 2000, to the first Interest Payment Date, and thereafter will
accrue from the last Interest Payment Date to which interest has been paid or
duly provided for. In the event that any Interest Payment Date is not a Business
Day, then payment of interest payable on such date will be made on the next
succeeding day which is a Business Day (except that if such Business Day is in
the next succeeding calendar month, payment will be made on the next preceding
Business Day) with the same force and effect as if made on the Interest Payment
Date. 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 Note (or one or more Predecessor Notes) is registered at the
close of business on the Regular Record Date for such interest, which shall be
the fifteenth day of the calendar month of such Interest Payment Date, provided,
however, that interest payable at Maturity will be paid to the Person to whom
principal is paid. 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 Note (or one or more
Predecessor Notes) 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 Notes of this series not less than
10 days prior to such Special Record Date, or be paid at any time in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Notes of this series may be listed, and upon such notice as may be
required by such exchange, all as more fully provided in the Indenture referred
to on the reverse hereof.

          Payment of the principal of and interest on this Note will be made
upon presentation at the office or agency of the Company maintained for that
purpose in The City of New York, the State 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, interest on this Note may be paid by check mailed to the address of
the person entitled thereto, as such address shall appear on the Note Register
or by wire transfer to an account designated by the person entitled thereto.

                                        2
<PAGE>
          Reference is hereby made to the further provisions of this Note 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 Note
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 Note to be duly
executed.



                                       COMMONWEALTH EDISON COMPANY

                                       By:____________________________________
                                                     Chairman

                                       By:____________________________________
                                                     Secretary


                          CERTIFICATE OF AUTHENTICATION

          This is one of the Notes of the series designated herein referred to
in the within-mentioned Indenture.

Dated:

                                       CITIBANK, N.A., as Trustee

                                       By:____________________________________
                                          Authorized Signatory

                                       3

<PAGE>
                             [Reverse of 2002 Note]

          This Note is one of a duly authorized issue of notes of the Company
(herein called the "Notes"), issued and to be issued in one or more series under
an Indenture dated as of September 1, 1987 (herein, together with any
supplements and amendments thereto, called the "Indenture") between the Company
and Citibank, N.A., as Trustee (herein called the "Trustee," which term includes
any successor trustee under the Indenture), and reference is hereby made to the
Indenture for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the Holders of
the Notes and of the terms upon which the Notes are, and are to be,
authenticated and delivered.

Interest Calculation

          The Notes of this series will bear interest at a per annum rate
("Interest Rate") determined by Citibank, N.A., or its successor appointed by
the Company as permitted by the Indenture, acting as calculation agent
("Calculation Agent"). The Interest Rate for each Interest Period will be equal
to LIBOR (as defined below) on the second London Business Day (as defined below)
immediately preceding the first day of such Interest Period ("Interest
Determination Date"), plus 0.500%; provided, however, that in certain
circumstances described below, the Interest Rate will be determined in an
alternative manner without reference to LIBOR. Promptly upon such determination,
the Calculation Agent will notify the Trustee of the Interest Rate for such
Interest Period. The determination of the Calculation Agent, absent manifest
error, shall be binding and conclusive upon the holders of this Note, the
Company and the Trustee.

          Interest on the Notes of this series will accrue from and including
September 21, 2000 ("Issue Date") to but excluding December 30, 2000 (the first
Interest Payment Date) and thereafter from and including each Interest Payment
Date to but excluding the next succeeding Interest Payment Date.

          "London Business Day" shall mean a day on which dealings in deposits
in U.S. Dollars are transacted, or with respect to any future date, are expected
to be transacted, in the London interbank market.

          "LIBOR," for any Interest Determination Date, will be the offered rate
for deposits in U.S. Dollars having an index maturity of three months for a
period commencing on the second London Business Day immediately following the
Interest Determination Date ("Three Month Deposits") in amounts of not less than
$1,000,000, as such rate appears on Telerate Page 3750 (as defined below), or a
successor reporter of such rates selected by the Calculation Agent and
acceptable to the Company, at approximately 11:00 A.M., London time, on the
Interest Determination Date ("Reported Rate").

          "Telerate Page 3750" means the display designated on page "3750" on
Dow Jones Markets Limited (or such other page as may replace the 3750 page on
that service or such other service or services as may be nominated by the
British Bankers' Association for the purpose of displaying London interbank
offered rates for U.S. Dollar deposits).

          If the following circumstances exist on any Interest Determination
Date, the Calculation Agent shall determine the Interest Rate for the Notes of
this series as follows:

                    (i) In the event no Reported Rate appears on Telerate Page
          3750 as of approximately 11:00 A.M. London time on an Interest
          Determination Date, the Calculation Agent shall request the principal
          London offices of each of four major banks in the London interbank
          market selected


<PAGE>
          by the Calculation Agent (after consultation with the Company) to
          provide a quotation of the rate ("Rate Quotation") at which Three
          Month Deposits in amounts of not less than $1,000,000 are offered by
          it to prime banks in the London interbank market, as of approximately
          11:00 A.M. London time on such Interest Determination Date, that is
          representative of single transactions at such time ("Representative
          Amounts"). If at least two Rate Quotations are provided, the Interest
          Rate will be the arithmetic mean of the Rate Quotations obtained by
          the Calculation Agent, plus 0.500%.

                    (ii) In the event no Reported Rate appears on Telerate Page
          3750 and there are fewer than two Rate Quotations, the Interest Rate
          will be the arithmetic mean of the rates quoted at approximately 11:00
          A.M. New York City time on such Interest Determination Date, by three
          major banks in New York, New York, selected by the Calculation Agent
          (after consultation with the Company), for loans in Representative
          Amounts in U.S. Dollars to leading European banks, having an index
          maturity of three months for a period commencing on the second London
          Business Day immediately following such Interest Determination Date,
          plus 0.500%; provided, however, that if fewer than three banks
          selected by the Calculation Agent are quoting such rates, the Interest
          Rate for the applicable period will be the same as the Interest Rate
          in effect for the immediately preceding Interest Period.

          Upon the request of the Holder of this Note, the Calculation Agent
will provide to such Holder the Interest Rate in effect on the date of such
request and, if determined, the Interest Rate for the next Interest Period.

          "Interest Period" shall mean the period commencing on an Interest
Payment Date and ending on the day preceding the next succeeding Interest
Payment Date, with the exception that the first Interest Period shall begin on
the Issue Date and extend through the day preceding the first Interest Payment
Date.

          If an Interest Payment Date or the Maturity Date for the Notes of this
series falls on a day that is not a Business Day in The City of New York, New
York, the related payment of interest or principal and interest may be made on
the next succeeding Business Day (except that if such Business Day is in the
next succeeding calendar month, payment will be made on the next preceding
Business Day) with the same force and effect as if it were made on the date such
payment was due.

          Interest will be computed for each Interest Period on the basis of the
actual number of days for which interest is payable in such Interest Period,
divided by 360. All percentages resulting from any calculation of any interest
rate for the Notes of this series will be rounded, if necessary, to the nearest
one hundred thousandth of a percentage point, with five one millionths of a
percentage point rounded upward and all dollar amounts will be rounded to the
nearest cent, with one-half cent being rounded upward.

Redemption

          The Notes of this series will not be redeemable prior to September 30,
2001; and thereafter may be redeemed at the option of the Company, in whole or
in part, beginning on September 30, 2001 and on the last Business Day of each
calendar month thereafter, at a redemption price equal to 100% of the principal
amount to be redeemed plus accrued and unpaid interest on such Notes to the date
of redemption. In order to redeem such Notes, Company will give not less than 30
nor more than 60 days prior notice mailed to each registered holder of the Notes
of this series to be redeemed at its registered address by first-class mail.

                                       5
<PAGE>
          If an Event of Default with respect to Notes of this series shall
occur and be continuing, the principal of the Notes of 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 under the Indenture at any time by the
Company and the Trustee with the consent of the Holders of a majority in
aggregate principal amount of the Notes at the time Outstanding of all series
which are affected by such amendment or modification, except that certain
amendments which do not adversely affect the rights of any Holder of the Notes
may be made without the approval of Holders of the Notes. The Indenture also
contains provisions permitting the Holders of a majority in aggregate principal
amount of the Notes at the time Outstanding of all series affected to waive on
behalf of the Holders of all Notes certain past defaults under the Indenture and
their consequences. Any such waiver or consent by the Holder of this Note shall
be conclusive and binding upon such Holder and upon all future Holders of this
Note and of any Note 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 Note.

          No reference herein to the Indenture and no provision of this Note 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 Note at the times, place and rate, and in the coin or currency, herein
prescribed.

          The Notes of this series are issuable only as Fully Registered Notes
in denominations of $100,000 and in integral multiples of $10,000 in excess
thereof. As provided in the Indenture and subject to certain limitations therein
set forth, Notes of this series are exchangeable for a like aggregate principal
amount of Notes of this series and of like tenor and of authorized
denominations, 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.

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

          Each Holder shall be deemed to understand that the offer and sale of
the Notes of this series have not been registered under the Securities Act and
that the Notes of this series may not be offered or sold except as permitted in
the following sentence. Each Holder shall be deemed to agree, on its own behalf
and on behalf of any accounts for which it is acting as hereinafter stated, that
if such Holder sells any Notes of this series, such Holder will do so only (A)
to the Company, (B) to a person whom it reasonably believes is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act
that purchases for its own account or for the account of a qualified
institutional buyer to whom notice is given that the resale, pledge or transfer
is being made in reliance on Rule 144A, (C) to an institutional "accredited
investor" (as defined in Rule 501(a)(1), (2), (3) or (7) under the Securities
Act) that, prior to such transfer, furnishes to the Trustee a signed letter
containing certain representations and agreements relating to the restrictions
on transfer of the Notes of this series, (D) in an offshore transaction in
accordance with Rule 904 of Regulation S under the Securities Act, (E) pursuant
to the exemption from registration provided by Rule 144 under the Securities Act
(if available), or (F) pursuant to an effective registration statement under the
Securities Act, and each Holder is further deemed to agree to provide to any

                                       6

<PAGE>
person purchasing any of the Notes of this series from it a notice advising such
purchaser that resales of the Notes of this series are restricted as stated
herein.

          Each Holder shall be deemed to understand that, on any proposed resale
of any Notes of this series pursuant to the exemption from registration under
Rule 144 under the Securities Act, any Holder making any such proposed resale
will be required to furnish to the Trustee and Company such certifications,
legal opinions and other information as the Trustee and Company may reasonably
require to confirm that the proposed sale complies with the foregoing
restrictions.

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

                                       7

<PAGE>
                             CERTIFICATE OF TRANSFER

                Floating Rate Senior Notes due September 30, 2002

          FOR VALUE RECEIVED, the undersigned sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE

     Name and address of assignee must be printed or typewritten.


the within Note of the Company and does hereby irrevocably constitute and
appoint _______________________ to transfer the said Note on the books of the
within-named Company, with full power of substitution in the premises. The
undersigned certifies that said Note is being resold, pledged or otherwise
transferred as follows: (check one)

|_|  to the Company;

|_|  to a Person whom the undersigned reasonably believes is a qualified
     institutional buyer within the meaning of Rule 144A under the Securities
     Act of 1933, as amended (the "Securities Act") purchasing for its own
     account or for the account of a qualified institutional buyer to whom
     notice is given that the resale, pledge or other transfer is being made in
     reliance on Rule 144A;

|_|  in an offshore transaction in accordance with Rule 904 of Regulation S
     under the Securities Act;

|_|  to an institution that is an "accredited investor" as defined in Rule
     501(a)(1), (2), (3) or (7) under the Securities Act that is acquiring this
     Note for investment purposes and not for distribution; (attach a copy of an
     Accredited Investor Certificate in the form annexed signed by an authorized
     officer of the transferee)

|_|  as otherwise permitted by the non-registration legend appearing on this
     Note; or

|_|  as otherwise agreed by the Company, confirmed in writing to the Trustee, as
     follows: [describe]



                                       ________________________________________
                                       Name:

                                       Title:



Dated:_________________________________________________________________________

                                       8

<PAGE>
                    [FORM OF ACCREDITED INVESTOR CERTIFICATE]



[Transferor Name and Address]

Ladies and Gentlemen:

     In connection with our proposed purchase of Floating Rate Senior Notes due
September 30, 2002 (the "Senior Notes") issued by Commonwealth Edison Company
("Issuer"), we confirm that:

          1. We have received a copy of the Offering Memorandum dated September
     14, 2000 (the "Offering Memorandum") relating to the Senior Notes and such
     other information as we deem necessary in order to make our investment
     decision. We acknowledge that we have read and agree to the matters stated
     under the caption NOTICE TO INVESTORS in such Offering Memorandum, and the
     restrictions on duplication or circulation of, or disclosure relating to,
     such Offering Memorandum.

          2. We understand that any subsequent transfer of the Senior Notes is
     subject to certain restrictions and conditions set forth in the Indenture
     dated as of September 1, 1987, as supplemented and amended (the
     "Indenture"), pursuant to which the Senior Notes have been issued, and that
     any subsequent transfer of the Senior Notes is subject to certain
     restrictions and conditions set forth under NOTICE TO INVESTORS in the
     Offering Memorandum and the undersigned agrees to be bound by, and not to
     resell, pledge or otherwise transfer the Senior Notes except in compliance
     with such restrictions and conditions and the Securities Act of 1933, as
     amended ("Securities Act").

          3. We understand that the offer and sale of the Senior Notes have not
     been registered under the Securities Act, and that the Senior Notes may not
     be offered or sold except as permitted in the following sentence. We agree,
     on our own behalf and on behalf of any accounts for which we are acting as
     hereinafter stated, that if we sell any Senior Notes, we will do so only
     (A) to the Company, (B) to a person whom we reasonably believe is a
     "qualified institutional buyer" within the meaning of Rule 144A under the
     Securities Act that purchases for its own account or for the account of a
     qualified institutional buyer to whom notice is given that the resale,
     pledge or transfer is being made in reliance on Rule 144A, (C) to an
     institutional "accredited investor"(as defined below) that, prior to such
     transfer, furnishes to the Trustee (as defined in the Indenture) a signed
     letter containing certain representations and agreements relating to the
     restrictions on transfer of the Senior Notes (substantially in the form of
     this letter), (D) in an offshore transaction in accordance with Rule 904 of
     Regulation S under the Securities Act, (E) pursuant to the exemption from
     registration provided by Rule 144 under the Securities Act (if available),
     or (F) in accordance with another applicable exemption from the
     registration requirements of the Securities Act, and we further agree to
     provide to any person purchasing any of the Senior Notes from us a notice
     advising such purchaser that resales of the Senior Notes are restricted as
     stated herein.

          4. We understand that, on any proposed resale of any Senior Note, we
     will be required to furnish to the Trustee and Issuer such certifications,
     legal opinions and other information as the Trustee and Issuer may
     reasonably require to confirm that the proposed sale complies with the
     forgoing restrictions. We further understand that the Senior Notes
     purchased by us will bear a legend to the foregoing effect.




<PAGE>
          5. We are an institutional "accredited investor" (as defined in Rule
     501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act) and
     have such knowledge and experience in financial and business matters as to
     be capable of evaluating the merits and risks of our investment in the
     Senior Notes, and we and any accounts for which are acting are each able to
     bear the economic risk of our or its investment.

          6. We are acquiring the Senior Notes purchased by us for our own
     account or for one or more accounts (each of which is an institutional
     "accredited investor") as to each of which we exercise sole investment
     discretion.

     You, the Issuer and the Trustee are entitled to rely upon this letter and
are irrevocably authorized to produce this letter or a copy hereof to any
interested party in any administrative or legal proceeding or official inquiry
with respect to the matters covered hereby.

                                       Very  truly  yours,

                                       By:_____________________________________
                                          Name:________________________________
                                          Title:_______________________________


                                       10

<PAGE>
                                                                       EXHIBIT B

            Form of Floating Rate Senior Note Due September 30, 2003
            --------------------------------------------------------

                               [depository legend]

          Unless this Certificate is presented by an authorized representative
of The Depository Trust Company, a New York corporation ("DTC"), 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 in such other name
as is requested by an authorized representative of DTC (and any payment 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 inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

                            [non-registration legend]

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS SECURITY,
AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE RESOLD,
PLEDGED OR OTHERWISE TRANSFERRED OTHER THAN (A) (1) TO THE COMPANY, (2) IN A
TRANSACTION ENTITLED TO AN EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144
UNDER THE SECURITIES ACT, (3) SO LONG AS THIS SECURITY IS ELIGIBLE FOR RESALE
PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE 144A"), TO A PERSON WHOM
THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE
MEANING OF RULE 144A PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A
QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR
OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A (AS INDICATED BY THE BOX
CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS
SECURITY), (4) IN AN OFFSHORE TRANSACTION IN ACCORDANCE WITH RULE 904 OF
REGULATION S UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY), (5)
TO AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1),
(2), (3) OR (7) UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY) THAT
IS ACQUIRING THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION, AND
A CERTIFICATE IN THE FORM ATTACHED TO THIS SECURITY IS DELIVERED BY THE
TRANSFEREE TO THE COMPANY AND THE TRUSTEE OR (6) IN ACCORDANCE WITH ANOTHER
APPLICABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT
(AND BASED UPON AN OPINION OF COUNSEL ACCEPTABLE TO THE COMPANY) AND (B) IN EACH
CASE IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF EACH STATE OF THE
UNITED STATES. AN INSTITUTIONAL ACCREDITED INVESTOR HOLDING THIS SECURITY AGREES
IT WILL FURNISH TO THE COMPANY AND THE TRUSTEE SUCH CERTIFICATES AND OTHER
INFORMATION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY TRANSFER BY IT OF
THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. tHE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A
OR (2) AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE
501(A)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT AND THAT IT IS HOLDING THIS
SECURITY FOR INVESTMENT PURPOSES AND NOT FOR




<PAGE>
DISTRIBUTION OR (3) A NON-u.S. PERSON OUTSIDE THE UNITED STATES WITHIN THE
MEANING OF, OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH (o)(2) OF
RULE 902 UNDER, REGULATION S UNDER THE SECURITIES ACT.


No. R-__                                                           Cusip No. ___

                               [FACE OF 2003 NOTE]

                           COMMONWEALTH EDISON COMPANY

                FLOATING RATE SENIOR NOTE DUE SEPTEMBER 30, 2003

          COMMONWEALTH EDISON COMPANY, a corporation duly organized and existing
under the laws of the State of Illinois (herein referred to as the "Company",
which term includes any successor corporation under the Indenture), for value
received, hereby promises to pay to



or registered assigns, the principal sum of _________________________ Dollars
($_________) on September 30, 2003, and to pay interest on said principal sum
quarterly on March 30, June 30, September 30 and December 30 of each year,
commencing December 30, 2000 (each an "Interest Payment Date") at the per annum
interest rate determined by the Calculation Agent on each Interest Determination
Date, as such terms are defined herein, until the principal hereof is paid or
made available for payment. Interest on the Notes of this series will accrue
from September 21, 2000, to the first Interest Payment Date, and thereafter will
accrue from the last Interest Payment Date to which interest has been paid or
duly provided for. In the event that any Interest Payment Date is not a Business
Day, then payment of interest payable on such date will be made on the next
succeeding day which is a Business Day (except that if such Business Day is in
the next succeeding calendar month, payment will be made on the next preceding
Business Day) with the same force and effect as if made on the Interest Payment
Date. 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 Note (or one or more Predecessor Notes) is registered at the
close of business on the Regular Record Date for such interest, which shall be
the fifteenth day of the calendar month of such Interest Payment Date, provided,
however, that interest payable at Maturity will be paid to the Person to whom
principal is paid. 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 Note (or one or more
Predecessor Notes) 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 Notes of this series not less than
10 days prior to such Special Record Date, or be paid at any time in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Notes of this series may be listed, and upon such notice as may be
required by such exchange, all as more fully provided in the Indenture referred
to on the reverse hereof.

          Payment of the principal of and interest on this Note will be made
upon presentation at the office or agency of the Company maintained for that
purpose in The City of New York, the State 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, interest on this Note may be paid by check mailed to the address of
the person entitled thereto, as such address shall appear on the Note Register
or by wire transfer to an account designated by the person entitled thereto.

                                       2
<PAGE>
          Reference is hereby made to the further provisions of this Note 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 Note
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 Note to be duly
executed.



                                       COMMONWEALTH EDISON COMPANY

                                       By:_____________________________________
                                                     Chairman

                                       By:_____________________________________
                                                     Secretary


                          CERTIFICATE OF AUTHENTICATION

          This is one of the Notes of the series designated herein referred to
in the within-mentioned Indenture.

Dated:

                                       CITIBANK, N.A., as Trustee

                                       By:_____________________________________
                                          Authorized Signatory

                                       3

<PAGE>
                             [Reverse of 2003 Note]

          This Note is one of a duly authorized issue of notes of the Company
(herein called the "Notes"), issued and to be issued in one or more series under
an Indenture dated as of September 1, 1987 (herein, together with any
supplements and amendments thereto, called the "Indenture") between the Company
and Citibank, N.A., as Trustee (herein called the "Trustee," which term includes
any successor trustee under the Indenture), and reference is hereby made to the
Indenture for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the Holders of
the Notes and of the terms upon which the Notes are, and are to be,
authenticated and delivered.

Interest Calculation

          The Notes of this series will bear interest at a per annum rate
("Interest Rate") determined by Citibank, N.A., or its successor appointed by
the Company as permitted by the Indenture, acting as calculation agent
("Calculation Agent"). The Interest Rate for each Interest Period will be equal
to LIBOR (as defined below) on the second London Business Day (as defined below)
immediately preceding the first day of such Interest Period ("Interest
Determination Date"), plus 0.625%; provided, however, that in certain
circumstances described below, the Interest Rate will be determined in an
alternative manner without reference to LIBOR. Promptly upon such determination,
the Calculation Agent will notify the Trustee of the Interest Rate for such
Interest Period. The determination of the Calculation Agent, absent manifest
error, shall be binding and conclusive upon the holders of this Note, the
Company and the Trustee.

          Interest on the Notes of this series will accrue from and including
September 21, 2000 ("Issue Date") to but excluding December 30, 2000 (the first
Interest Payment Date) and thereafter from and including each Interest Payment
Date to but excluding the next succeeding Interest Payment Date.

          "London Business Day" shall mean a day on which dealings in deposits
in U.S. Dollars are transacted, or with respect to any future date, are expected
to be transacted, in the London interbank market.

          "LIBOR," for any Interest Determination Date, will be the offered rate
for deposits in U.S. Dollars having an index maturity of three months for a
period commencing on the second London Business Day immediately following the
Interest Determination Date ("Three Month Deposits") in amounts of not less than
$1,000,000, as such rate appears on Telerate Page 3750 (as defined below), or a
successor reporter of such rates selected by the Calculation Agent and
acceptable to the Company, at approximately 11:00 A.M., London time, on the
Interest Determination Date ("Reported Rate").

          "Telerate Page 3750" means the display designated on page "3750" on
Dow Jones Markets Limited (or such other page as may replace the 3750 page on
that service or such other service or services as may be nominated by the
British Bankers' Association for the purpose of displaying London interbank
offered rates for U.S. Dollar deposits).

          If the following circumstances exist on any Interest Determination
Date, the Calculation Agent shall determine the Interest Rate for the Notes of
this series as follows:

                    (i) In the event no Reported Rate appears on Telerate Page
          3750 as of approximately 11:00 A.M. London time on an Interest
          Determination Date, the Calculation Agent shall request the principal
          London offices of each of four major banks in the London interbank
          market selected


<PAGE>
          by the Calculation Agent (after consultation with the Company) to
          provide a quotation of the rate ("Rate Quotation") at which Three
          Month Deposits in amounts of not less than $1,000,000 are offered by
          it to prime banks in the London interbank market, as of approximately
          11:00 A.M. London time on such Interest Determination Date, that is
          representative of single transactions at such time ("Representative
          Amounts"). If at least two Rate Quotations are provided, the Interest
          Rate will be the arithmetic mean of the Rate Quotations obtained by
          the Calculation Agent, plus 0.625%.

                    (ii) In the event no Reported Rate appears of Telerate Page
          3750 and there are fewer than two Rate Quotations, the Interest Rate
          will be the arithmetic mean of the rates quoted at approximately 11:00
          A.M. New York City time on such Interest Determination Date, by three
          major banks in New York, New York, selected by the Calculation Agent
          (after consultation with the Company), for loans in Representative
          Amounts in U.S. Dollars to leading European banks, having an index
          maturity of three months for a period commencing on the second London
          Business Day immediately following such Interest Determination Date,
          plus 0.625%; provided, however, that if fewer than three banks
          selected by the Calculation Agent are quoting such rates, the Interest
          Rate for the applicable period will be the same as the Interest Rate
          in effect for the immediately preceding Interest Period.

          Upon the request of the Holder of this Note, the Calculation Agent
will provide to such Holder the Interest Rate in effect on the date of such
request and, if determined, the Interest Rate for the next Interest Period.

          "Interest Period" shall mean the period commencing on an Interest
Payment Date and ending on the day preceding the next succeeding Interest
Payment Date, with the exception that the first Interest Period shall begin on
the Issue Date and extend through the day preceding the first Interest Payment
Date.

          If an Interest Payment Date or the Maturity Date for the Notes of this
series falls on a day that is not a Business Day in The City of New York, New
York, the related payment of interest or principal and interest may be made on
the next succeeding Business Day (except that if such Business Day is in the
next succeeding calendar month, payment will be made on the next preceding
Business Day) with the same force and effect as if it were made on the date such
payment was due.

          Interest will be computed for each Interest Period on the basis of the
actual number of days for which interest is payable in such Interest Period,
divided by 360. All percentages resulting from any calculation of any interest
rate for the Notes of this series will be rounded, if necessary, to the nearest
one hundred thousandth of a percentage point, with five one millionths of a
percentage point rounded upward and all dollar amounts will be rounded to the
nearest cent, with one-half cent being rounded upward.

Redemption

          The Notes of this series will not be redeemable prior to September 30,
2001; and thereafter may be redeemed at the option of the Company, in whole or
in part, beginning on September 30, 2001 and on the last Business Day of each
calendar month thereafter, at a redemption price equal to 100% of the principal
amount to be redeemed plus accrued and unpaid interest on such Notes to the date
of redemption. In order to redeem such Notes, Company will give not less than 30
nor more than 60 days prior notice mailed to each registered holder of the Notes
of this series to be redeemed at its registered address by first-class mail.

                                        5
<PAGE>
          If an Event of Default with respect to Notes of this series shall
occur and be continuing, the principal of the Notes of 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 under the Indenture at any time by the
Company and the Trustee with the consent of the Holders of a majority in
aggregate principal amount of the Notes at the time Outstanding of all series
which are affected by such amendment or modification, except that certain
amendments which do not adversely affect the rights of any Holder of the Notes
may be made without the approval of Holders of the Notes. The Indenture also
contains provisions permitting the Holders of a majority in aggregate principal
amount of the Notes at the time Outstanding of all series affected to waive on
behalf of the Holders of all Notes certain past defaults under the Indenture and
their consequences. Any such waiver or consent by the Holder of this Note shall
be conclusive and binding upon such Holder and upon all future Holders of this
Note and of any Note 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 Note.

          No reference herein to the Indenture and no provision of this Note 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 Note at the times, place and rate, and in the coin or currency, herein
prescribed.

          The Notes of this series are issuable only as Fully Registered Notes
in denominations of $100,000 and in integral multiples of $10,000 in excess
thereof. As provided in the Indenture and subject to certain limitations therein
set forth, Notes of this series are exchangeable for a like aggregate principal
amount of Notes of this series and of like tenor and of authorized
denominations, 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.

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

          Each Holder shall be deemed to understand that the offer and sale of
the Notes of this series have not been registered under the Securities Act and
that the Notes of this series may not be offered or sold except as permitted in
the following sentence. Each Holder shall be deemed to agree, on its own behalf
and on behalf of any accounts for which it is acting as hereinafter stated, that
if such Holder sells any Notes of this series, such Holder will do so only (A)
to the Company, (B) to a person whom it reasonably believes is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act
that purchases for its own account or for the account of a qualified
institutional buyer to whom notice is given that the resale, pledge or transfer
is being made in reliance on Rule 144A, (C) to an institutional "accredited
investor" (as defined in Rule 501(a)(1), (2), (3) or (7) under the Securities
Act) that, prior to such transfer, furnishes to the Trustee a signed letter
containing certain representations and agreements relating to the restrictions
on transfer of the Notes of this series, (D) in an offshore transaction in
accordance with Rule 904 of Regulation S under the Securities Act, (E) pursuant
to the exemption from registration provided by Rule 144 under the Securities Act
(if available), or (F) pursuant to an effective registration statement under the
Securities Act, and each Holder is further deemed to agree to provide to

                                       6
<PAGE>
any person purchasing any of the Notes of this series from it a notice advising
such purchaser that resales of the Notes of this series are restricted as stated
herein.

          Each Holder shall be deemed to understand that, on any proposed resale
of any Notes of this series pursuant to the exemption from registration under
Rule 144 under the Securities Act, any Holder making any such proposed resale
will be required to furnish to the Trustee and Company such certifications,
legal opinions and other information as the Trustee and Company may reasonably
require to confirm that the proposed sale complies with the foregoing
restrictions.

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

                                       7

<PAGE>
                             CERTIFICATE OF TRANSFER

                Floating Rate Senior Notes due September 30, 2003

          FOR VALUE RECEIVED, the undersigned sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE

     Name and address of assignee must be printed or typewritten.


the within Note of the Company and does hereby irrevocably constitute and
appoint _______________________ to transfer the said Note on the books of the
within-named Company, with full power of substitution in the premises. The
undersigned certifies that said Note is being resold, pledged or otherwise
transferred as follows: (check one)

|_|  to the Company;

|_|  to a Person whom the undersigned reasonably believes is a qualified
     institutional buyer within the meaning of Rule 144A under the Securities
     Act of 1933, as amended (the "Securities Act") purchasing for its own
     account or for the account of a qualified institutional buyer to whom
     notice is given that the resale, pledge or other transfer is being made in
     reliance on Rule 144A;

|_|  in an offshore transaction in accordance with Rule 904 of Regulation S
     under the Securities Act;

|_|  to an institution that is an "accredited investor" as defined in Rule
     501(a)(1), (2), (3) or (7) under the Securities Act that is acquiring this
     Note for investment purposes and not for distribution; (attach a copy of an
     Accredited Investor Certificate in the form annexed signed by an authorized
     officer of the transferee)

|_|  as otherwise permitted by the non-registration legend appearing on this
     Note; or

|_|  as otherwise agreed by the Company, confirmed in writing to the Trustee, as
     follows: [describe]

                                       ________________________________________
                                       Name:

                                       Title:



Dated:_________________________________________________________________________

                                       8

<PAGE>
                    [FORM OF ACCREDITED INVESTOR CERTIFICATE]



[Transferor Name and Address]

Ladies and Gentlemen:

     In connection with our proposed purchase of Floating Rate Senior Notes due
September 30, 2003 (the "Senior Notes") issued by Commonwealth Edison Company
("Issuer"), we confirm that:

          1. We have received a copy of the Offering Memorandum dated September
     14, 2000 (the "Offering Memorandum") relating to the Senior Notes and such
     other information as we deem necessary in order to make our investment
     decision. We acknowledge that we have read and agree to the matters stated
     under the caption NOTICE TO INVESTORS in such Offering Memorandum, and the
     restrictions on duplication or circulation of, or disclosure relating to,
     such Offering Memorandum.

          2. We understand that any subsequent transfer of the Senior Notes is
     subject to certain restrictions and conditions set forth in the Indenture
     dated as of September 1, 1987, as supplemented and amended (the
     "Indenture"), pursuant to which the Senior Notes have been issued, and that
     any subsequent transfer of the Senior Notes is subject to certain
     restrictions and conditions set forth under NOTICE TO INVESTORS in the
     Offering Memorandum and the undersigned agrees to be bound by, and not to
     resell, pledge or otherwise transfer the Senior Notes except in compliance
     with such restrictions and conditions and the Securities Act of 1933, as
     amended ("Securities Act").

          3. We understand that the offer and sale of the Senior Notes have not
     been registered under the Securities Act, and that the Senior Notes may not
     be offered or sold except as permitted in the following sentence. We agree,
     on our own behalf and on behalf of any accounts for which we are acting as
     hereinafter stated, that if we sell any Senior Notes, we will do so only
     (A) to the Company, (B) to a person whom we reasonably believe is a
     "qualified institutional buyer" within the meaning of Rule 144A under the
     Securities Act that purchases for its own account or for the account of a
     qualified institutional buyer to whom notice is given that the resale,
     pledge or transfer is being made in reliance on Rule 144A, (C) to an
     institutional "accredited investor"(as defined below) that, prior to such
     transfer, furnishes to the Trustee (as defined in the Indenture) a signed
     letter containing certain representations and agreements relating to the
     restrictions on transfer of the Senior Notes (substantially in the form of
     this letter), (D) in an offshore transaction in accordance with Rule 904 of
     Regulation S under the Securities Act, (E) pursuant to the exemption from
     registration provided by Rule 144 under the Securities Act (if available),
     or (F) in accordance with another applicable exemption from the
     registration requirements of the Securities Act, and we further agree to
     provide to any person purchasing any of the Senior Notes from us a notice
     advising such purchaser that resales of the Senior Notes are restricted as
     stated herein.

          4. We understand that, on any proposed resale of any Senior Note, we
     will be required to furnish to the Trustee and Issuer such certifications,
     legal opinions and other information as the Trustee and Issuer may
     reasonably require to confirm that the proposed sale complies with the
     forgoing restrictions. We further understand that the Senior Notes
     purchased by us will bear a legend to the foregoing effect.

<PAGE>
          5. We are an institutional "accredited investor" (as defined in Rule
     501(a)(1), (2), (3) or (7) of Regulation D under the Securities Act) and
     have such knowledge and experience in financial and business matters as to
     be capable of evaluating the merits and risks of our investment in the
     Senior Notes, and we and any accounts for which are acting are each able to
     bear the economic risk of our or its investment.

          6. We are acquiring the Senior Notes purchased by us for our own
     account or for one or more accounts (each of which is an institutional
     "accredited investor") as to each of which we exercise sole investment
     discretion.

     You, the Issuer and the Trustee are entitled to rely upon this letter and
are irrevocably authorized to produce this letter or a copy hereof to any
interested party in any administrative or legal proceeding or official inquiry
with respect to the matters covered hereby.

                                       Very  truly  yours,

                                       By:_____________________________________
                                          Name:________________________________
                                          Title:_______________________________


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