<PAGE>
                                                                     EXHIBIT 4-4



This instrument was prepared by,
and when recorded should be
returned to:


Richard W. Astle
Sidley Austin Brown & Wood
Bank One Plaza
10 South Dearborn Street
Chicago, Illinois 60603


================================================================================

                         FORM OF SUPPLEMENTAL INDENTURE

                                   ----------

                        Dated as of ___________ __, 200_

                                   ----------

                           COMMONWEALTH EDISON COMPANY

                                       to

                            BNY MIDWEST TRUST COMPANY

                                       and

                                  D. G. DONOVAN

             Trustees under Mortgage Dated July 1, 1923, and Certain
                         Indentures Supplemental Thereto

                                   ----------

                            Providing for Issuance of

                      FIRST MORTGAGE ___% BONDS, SERIES 99
                              DUE ________ __, 20__

                                       and

                      FIRST MORTGAGE __% BONDS, SERIES 100
                              DUE _______ __, 20__

================================================================================
<PAGE>
THIS SUPPLEMENTAL INDENTURE, dated as of ________ __, 200_, between COMMONWEALTH
EDISON COMPANY, a corporation organized and existing under the laws of the State
of Illinois (hereinafter called the "Company") having an address at 10 South
Dearborn Street, 37th floor, Chicago, Illinois 60603, party of the first part,
and BNY MIDWEST TRUST COMPANY, a trust company organized and existing under the
laws of the State of Illinois having an address at 2 North LaSalle Street, Suite
1020, Chicago, Illinois 60602, and D.G. DONOVAN, an individual having an address
at 2 North LaSalle Street, Suite 1020, Chicago, Illinois 60602, as Trustee and
Co-Trustee, respectively, under the Mortgage of the Company dated July 1, 1923,
as amended and supplemented by Supplemental Indenture dated August 1, 1944 and
the subsequent supplemental indentures hereinafter mentioned, parties of the
second part (said Trustee being hereinafter called the "Trustee", the Trustee
and said Co-Trustee being hereinafter together called the "Trustees", and said
Mortgage dated July 1, 1923, as amended and supplemented by said Supplemental
Indenture dated August 1, 1944 and subsequent supplemental indentures, being
hereinafter called the "Mortgage"),


                                   WITNESSETH:

     WHEREAS, the Company duly executed and delivered the Mortgage to provide
for the issue of, and to secure, its bonds, issuable in series and without limit
as to principal amount except as provided in the Mortgage; and

     WHEREAS, the Company from time to time has executed and delivered
supplemental indentures to the Mortgage to provide for (i) the creation of
additional series of bonds secured by the Mortgage, (ii) the amendment of
certain of the terms and provisions of the Mortgage and (iii) the confirmation
of the lien of the Mortgage upon property of the Company, such supplemental
indentures that are currently effective and the respective dates, parties
thereto and purposes thereof, being as follows:

<TABLE>
<CAPTION>
SUPPLEMENTAL
INDENTURE DATE         PARTIES                                PROVIDING FOR
<S>                    <C>                                    <C>
August 1, 1944         Company to Continental Illinois        Amendment and restatement
                       National Bank and Trust Company of     of Mortgage dated July 1,
                       Chicago and Edmond B. Stofft, as       1923
                       Trustee and Co-Trustee

August 1, 1946         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Edmond B. Stofft, as
                       Trustee and Co-Trustee

April 1, 1953          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Edmond B. Stofft, as
                       Trustee and Co-Trustee

March 31, 1967         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Edward J. Friedrich, as
                       Trustee and Co-Trustee
</TABLE>

                                      -1-
<PAGE>
<TABLE>
<CAPTION>
SUPPLEMENTAL
INDENTURE DATE         PARTIES                                PROVIDING FOR
<S>                    <C>                                    <C>
April 1, 1967          Company to Continental Illinois        Amendment of Sections 3.01,
                       National Bank and Trust Company of     3.02, 3.05 and 3.14 of the
                       Chicago and Edward J. Friedrich, as    Mortgage and issuance of
                       Trustee and Co-Trustee                 First Mortgage 5-3/8%
                                                              Bonds, Series Y

February 28, 1969      Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

May 29, 1970           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

June 1, 1971           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 1, 1972          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

May 31, 1972           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

June 15, 1973          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

May 31, 1974           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

June 13, 1975          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

May 28, 1976           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

June 3, 1977           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

May 17, 1978           Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

August 31, 1978        Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee
</TABLE>

                                      -2-
<PAGE>
<TABLE>
<CAPTION>
SUPPLEMENTAL
INDENTURE DATE         PARTIES                                PROVIDING FOR
<S>                    <C>                                    <C>
June 18, 1979          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

June 20, 1980          Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 16, 1981         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 30, 1982         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 15, 1983         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 13, 1984         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 15, 1985         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and Donald W. Alfvin, as
                       Trustee and Co-Trustee

April 15, 1986         Company to Continental Illinois        Confirmation of mortgage
                       National Bank and Trust Company of     lien
                       Chicago and M.J. Kruger, as Trustee
                       and Co-Trustee

June 15, 1990          Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          9-7/8% Bonds, Series 75
                       Kruger, as Trustee and Co-Trustee

October 1, 1991        Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          8-1/4% Bonds, Series 76 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 8-7/8%
                                                              Bonds, Series 77

October 15, 1991       Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          8-3/8% Bonds, Series 78 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 9-1/8%
                                                              Bonds, Series 79

February 1, 1992       Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          7% Bonds, Series 80 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 8-5/8%
                                                              Bonds, Series 81

May 15, 1992           Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          6-1/8% Bonds, Series 82 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 8% Bonds,
                                                              Series 83
</TABLE>

                                      -3-
<PAGE>
<TABLE>
<CAPTION>
SUPPLEMENTAL
INDENTURE DATE         PARTIES                                PROVIDING FOR
<S>                    <C>                                    <C>
July 15, 1992          Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          8-1/2% Bonds, Series 84
                       Kruger, as Trustee and Co-Trustee

September 15, 1992     Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          7-3/8% Bonds, Series 85 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 8-3/8%
                                                              Bonds, Series 86

February 1, 1993       Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          8-3/8% Bonds, Series 88
                       Kruger, as Trustee and Co-Trustee

April 1, 1993          Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          6-1/2% Bonds, Series 90 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 8% Bonds,
                                                              Series 91

April 15, 1993         Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          7-5/8% Bonds, Series 92
                       Kruger, as Trustee and Co-Trustee

June 15, 1993          Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          7% Bonds, Series 93 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 7-1/2%
                                                              Bonds, Series 94

July 15, 1993          Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          6-5/8% Bonds, Series 96 and
                       Kruger, as Trustee and Co-Trustee      First Mortgage 7-3/4%
                                                              Bonds, Series 97

January 15, 1994       Company to Continental Bank,           Issuance of First Mortgage
                       National Association and M.J.          Bonds, Pollution Control
                       Kruger, as Trustee and Co-Trustee      Series 1994A, 1994B and
                                                              1994C

December 1, 1994       Company to Bank of America Illinois    Issuance of First Mortgage
                       and Robert J. Donahue, as Trustee      Bonds, Pollution Control
                       and Co-Trustee                         Series 1994D

June 1, 1996           Company to Harris Trust and Savings    Issuance of First Mortgage
                       Bank and D.G. Donovan, as Trustee      Bonds, Pollution Control
                       and Co-Trustee                         Series 1996A and 1996B

March 1, 2002          Company to BNY Midwest Trust Company   Issuance of First Mortgage
                       and D.G. Donovan, as Trustee and       6.15% Bonds, Series 98
                       Co-Trustee

May 20, 2002           Company to BNY Midwest Trust Company   Issuance of First Mortgage
                       and D.G. Donovan, as Trustee and       Bonds, Pollution Control
                       Co-Trustee                             Series 2002

June 1, 2002           Company to BNY Midwest Trust Company   Issuance of additional
                       and D.G. Donovan, as Trustee and       First Mortgage 6.15% Bonds,
                       Co-Trustee                             Series 98

October 7, 2002        Company to BNY Midwest Trust Company   Issuance of registered
                       and D.G. Donovan, as Trustee and       First Mortgage 6.15% Bonds,
                       Co-Trustee                             Series 98 in exchange for
                                                              unregistered First Mortgage
                                                              6.15% Bonds, Series 98
</TABLE>

                                      -4-
<PAGE>
     WHEREAS, the respective designations, maturity dates and principal amounts
of the bonds of each series presently outstanding under, and secured by, the
Mortgage and the several supplemental indentures above referred to, are as
follows:

<TABLE>
<CAPTION>
              DESIGNATION                        MATURITY DATE             PRINCIPAL AMOUNT
<S>                                           <C>                          <C>
First Mortgage 9-7/8% Bonds, Series 75        June 15, 2020                    $54,171,000

First Mortgage 8-1/4% Bonds, Series 76        October 1, 2006                  100,000,000

First Mortgage 8-3/8% Bonds, Series 78        October 15, 2006                 125,000,000

First Mortgage 8-5/8% Bonds, Series 81        February 1, 2022                 200,000,000

First Mortgage 8% Bonds, Series 83            May 15, 2008                     140,000,000

First Mortgage 8-1/2% Bonds, Series 84        July 15, 2022                    200,000,000

First Mortgage 8-3/8% Bonds, Series 88        February 15, 2023                235,950,000

First Mortgage 8% Bonds, Series 91            April 15, 2023                   160,000,000

First Mortgage 7-5/8% Bonds, Series 92        April 15, 2013                   220,000,000

First Mortgage 7% Bonds, Series 93            July 1, 2005                     225,000,000

First Mortgage 7-1/2% Bonds, Series 94        July 1, 2013                     150,000,000

First Mortgage 6-5/8% Bonds, Series 96        July 15, 2003                    100,000,000

First Mortgage 7-3/4% Bonds, Series 97        July 15, 2023                    150,000,000

First Mortgage 5.3% Bonds, Pollution          January 15, 2004                  26,000,000
Control Series 1994A

First Mortgage 5.7% Bonds, Pollution          January 15, 2009                  20,000,000
Control Series 1994B

First Mortgage 5.85% Bonds, Pollution         January 15, 2014                  20,000,000
Control Series 1994C

First Mortgage 6.75% Bonds, Pollution         March 1, 2015                     91,000,000
Control Series 1994D

First Mortgage 4.4% Bonds, Pollution          December 1, 2006                 110,000,000
Control Series 1996A

First Mortgage 4.4% Bonds, Pollution          December 1, 2006                  89,400,000
</TABLE>

                                      -5-
<PAGE>

<TABLE>
<CAPTION>
              DESIGNATION                        MATURITY DATE             PRINCIPAL AMOUNT
<S>                                           <C>                          <C>
Control Series 1996B

First Mortgage 6.15% Bonds, Series 98         March 15, 2012                   600,000,000

First Mortgage Bonds, Pollution Control       April 15, 2013                   100,000,000
Series 2002
                                                                            --------------
                                              Total                         $3,516,521,000
                                                                            ==============
</TABLE>

     WHEREAS, the Mortgage provides for the issuance from time to time
thereunder, in series, of bonds of the Company for the purposes and subject to
the limitations therein specified; and

     WHEREAS, the Company desires, by this Supplemental Indenture, to create two
additional series of bonds to be issuable under the Mortgage, such bonds to be
designated "First Mortgage ___% Bonds, Series 99" (hereinafter called the "bonds
of Series 99") and "First Mortgage __% Bonds, Series 100" (hereinafter called
the "bonds of Series 100") and the terms and provisions to be contained in the
bonds of Series 99 or the bonds of Series 100, respectively or to be otherwise
applicable thereto to be as set forth in this Supplemental Indenture; and

     WHEREAS, the bonds of Series 99 and the Trustee's certificate to be
endorsed thereon and the bonds of Series 100 and the Trustee's certificate to be
endorsed thereon shall be substantially in the form of the General Form of
Registered Bond Without Coupons and the form of the General Form of Trustee's
Certificate set forth in Section 3.05 of the Supplemental Indenture dated August
1, 1944 to the Mortgage with such appropriate insertions, omissions and
variations in order to express the designation, date, maturity date, annual
interest rate, record dates for, and dates of, payment of interest,
denominations, terms of redemption and redemption prices, and other terms and
characteristics authorized or permitted by the Mortgage or not inconsistent
therewith; and

     WHEREAS, the Company is legally empowered and has been duly authorized by
the necessary corporate action and by order of the Illinois Commerce Commission
to make, execute and deliver this Supplemental Indenture, and to create, as an
additional series of bonds of the Company, the bonds of Series 99 and the bonds
of Series 100, and all acts and things whatsoever necessary to make this
Supplemental Indenture, when executed and delivered by the Company and the
Trustees, a valid, binding and legal instrument, and to make the bonds of Series
99 and the bonds of Series 100, when authenticated by the Trustee and issued as
in the Mortgage and in this Supplemental Indenture provided, the valid, binding
and legal obligations of the Company, entitled in all respects to the security
of the Mortgage, as amended and supplemented, have been done and performed;

                                      -6-
<PAGE>
     NOW, THEREFORE, in consideration of the premises and of the sum of one
dollar duly paid by the Trustees to the Company, and for other good and valuable
consideration, the receipt of which is hereby acknowledged, the parties hereto
do hereby agree as follows:

     SECTION 1. DESIGNATION AND ISSUANCE OF BONDS OF SERIES 99 AND BONDS OF
SERIES 100. The bonds of Series 99 shall, as hereinbefore recited, be designated
as the Company's "First Mortgage ____% Bonds, Series 99." The bonds of Series
100 shall, as hereinbefore recited, be designated as the Company's "First
Mortgage ___% Bonds, Series 100." Subject to the provisions of the Mortgage, the
bonds of Series 99 and the bonds of Series 100 shall be issuable without
limitation as to the aggregate principal amount thereof.

     SECTION 2. FORM, DATE, MATURITY DATE, INTEREST RATE AND INTEREST PAYMENT
DATES OF BONDS OF SERIES 99 AND BONDS OF SERIES 100. (a) The definitive bonds of
Series 99 and the definitive bonds of Series 100 shall be in engraved,
lithographed, printed or typewritten form and shall be registered bonds without
coupons; and such bonds and the Trustee's certificate to be endorsed thereon
shall be substantially in the forms hereinbefore recited, respectively. The
bonds of Series 99 and the bonds of Series 100 shall be dated as provided in
Section 3.01 of the Mortgage, as amended by Supplemental Indenture dated April
1, 1967.

     (b)      The bonds of Series 99 shall mature on ________ __, 20__. The
bonds of Series 100 shall mature on ______ __, 20__.

     (c)      The bonds of Series 99 shall bear interest at the rate of ____%
per annum until the principal thereof shall be paid. The bonds of Series 100
shall bear interest at the rate of ___% per annum until the principal thereof
shall be paid.

     (d)      Interest on the bonds of Series 99 and the bonds of Series 100
shall be payable semi-annually on the ______ day of _____ and the _______ day of
________ in each year, commencing ________ __, 20__. _______ __ and _______ __
in each year are hereby established as record dates for the payment of interest
payable on the next succeeding interest payment dates, respectively. The
interest on each bond of Series 99 and each bond of Series 100 so payable on any
interest payment date shall, subject to the exceptions provided in Section 3.01
of the Mortgage, as amended by said Supplemental Indenture dated April 1, 1967,
be paid to the person in whose name such bond is registered at the close of
business on the ______ __ or ________ __, as the case may be, next preceding
such interest payment date.

     SECTION 3. EXECUTION OF BONDS OF SERIES 99 AND BONDS OF SERIES 100. The
bonds of Series 99 and bonds of Series 100 shall be executed on behalf of the
Company by its President or one of its Vice Presidents, manually or by facsimile
signature, and shall have its corporate seal affixed thereto or a facsimile of
such seal imprinted thereon, attested by its Secretary or one of its Assistant
Secretaries, manually or by facsimile signature, all as may be provided by
resolution of the Board of Directors of the Company. In case any officer or
officers whose signature or signatures, manual or facsimile, shall appear upon
any bond of Series 99 or any bond of Series

                                      -7-
<PAGE>
100 shall cease to be such officer or officers before such bond shall have been
actually authenticated and delivered, such bond nevertheless may be issued,
authenticated and delivered with the same force and effect as though the person
or persons whose signature or signatures, manual or facsimile, appear thereon
had not ceased to be such officer or officers of the Company.

     SECTION 4. MEDIUM AND PLACES OF PAYMENT OF PRINCIPAL OF AND INTEREST ON
BONDS OF SERIES 99 AND BONDS OF SERIES 100; TRANSFERABILITY AND EXCHANGEABILITY.
Both the principal of and interest on the bonds of Series 99 and the bonds of
Series 100 shall be payable in any coin or currency of the United States of
America which at the time of payment is legal tender for the payment of public
and private debts, and both such principal and interest shall be payable at the
office or agency of the Company in the City of Chicago, State of Illinois, or,
at the option of the registered owner, at the office or agency of the Company in
the Borough of Manhattan, The City of New York, State of New York, and such
bonds shall be transferable and exchangeable, in the manner provided in Sections
3.09 and 3.10 of the Mortgage, at said office or agency. No charge shall be made
by the Company to the registered owner of any bond of Series 99 or any bond of
Series 100 for the transfer of such bond or for the exchange thereof for bonds
of other authorized denominations, except, in the case of transfer, a charge
sufficient to reimburse the Company for any stamp or other tax or governmental
charge required to be paid by the Company or the Trustee.

     SECTION 5. DENOMINATIONS AND NUMBERING OF BONDS OF SERIES 99 AND BONDS OF
SERIES 100. The bonds of Series 99 and bonds of Series 100 shall be issued in
the denomination of $1,000 and in such multiples of $1,000 as shall from time to
time hereafter be determined and authorized by the Board of Directors of the
Company or by any officer or officers of the Company authorized to make such
determination, the authorization of the denomination of any bond of Series 99 or
any bond of Series 100 to be conclusively evidenced by the execution thereof on
behalf of the Company. Bonds of Series 99 shall be numbered R-1 and
consecutively upwards, and bonds of Series 100 shall be numbered R-1 and
consecutively upwards.

     SECTION 6. TEMPORARY BONDS OF SERIES 99 AND BONDS OF SERIES 100. Until
definitive bonds of Series 99 or definitive bonds of Series 100 are ready for
delivery, there may be authenticated and issued in lieu of any thereof and
subject to all of the provisions, limitations and conditions set forth in
Section 3.11 of the Mortgage, temporary registered bonds without coupons of
Series 99 or temporary registered bonds without coupons of Series 100.

     SECTION 7. REDEMPTION OF BONDS OF SERIES 99 AND BONDS OF SERIES 100. (a)
The bonds of Series 99 shall be redeemable, at the option of the Company, as a
whole or in part, at any time upon notice sent by the Company through the mail,
postage prepaid, at least thirty (30) days and not more than forty-five (45)
days prior to the date fixed for redemption, to the registered holder of each
bond to be redeemed in whole or in part, addressed to such holder at his address
appearing upon the registration books, at a redemption price equal to the
greater of

                                      -8-
<PAGE>
          (1) 100% of the principal amount of the bonds of Series 99 to be
     redeemed, plus accrued interest to the redemption date, or

          (2) as determined by the Quotation Agent (as hereinafter defined), the
     sum of the present values of the remaining scheduled payments of principal
     and interest on the bonds of Series 99 to be redeemed (not including any
     portion of payments of interest accrued as of the redemption date)
     discounted to the redemption date on a semi-annual basis (assuming a
     360-day year consisting of twelve 30-day months) at the Adjusted Treasury
     Rate (as hereinafter defined) plus ______ (___) basis points, plus accrued
     interest to the redemption date.

Unless the Company defaults in payment of the redemption price, on and after the
redemption date, interest will cease to accrue on the bonds of Series 99 or
portions of the bonds of Series 99 called for redemption.

     (b) The bonds of Series 100 shall be redeemable, at the option of the
Company, as a whole or in part, at any time upon notice sent by the Company
through the mail, postage prepaid, at least thirty (30) days and not more than
forty-five (45) days prior to the date fixed for redemption, to the registered
holder of each bond to be redeemed in whole or in part, addressed to such holder
at his address appearing upon the registration books, at a redemption price
equal to the greater of

          (1) 100% of the principal amount of the bonds of Series 100 to be
     redeemed, plus accrued interest to the redemption date, or

          (2) as determined by the Quotation Agent (as hereinafter defined), the
     sum of the present values of the remaining scheduled payments of principal
     and interest on the bonds of Series 100 to be redeemed (not including any
     portion of payments of interest accrued as of the redemption date)
     discounted to the redemption date on a semi-annual basis (assuming a
     360-day year consisting of twelve 30-day months) at the Adjusted Treasury
     Rate (as hereinafter defined) plus ______ (___) basis points, plus accrued
     interest to the redemption date.

Unless the Company defaults in payment of the redemption price, on and after the
redemption date, interest will cease to accrue on the bonds of Series 100 or
portions of the bonds of Series 100 called for redemption.

     (c) For purposes of the foregoing Sections 7(a) and 7(b), the following
terms shall have the respective meanings set forth below:

          "Adjusted Treasury Rate" means, with respect to any redemption date,
     the rate per year equal to the semi-annual equivalent yield to maturity of
     the Comparable Treasury Issue, assuming a price for the Comparable Treasury
     Issue (expressed as a percentage of its principal amount) equal to the
     Comparable Treasury Price for the redemption date.

                                      -9-
<PAGE>
          "Business Day" means any day that is not a day on which banking
     institutions in New York City are authorized or required by law or
     regulation to close.

          "Comparable Treasury Issue" means the United States Treasury security
     selected by the Quotation Agent as having a maturity comparable to the
     remaining term of the bonds of Series 99 or the bonds of Series 100, as
     applicable, that would be used, at the time of selection and in accordance
     with customary financial practice, in pricing new issues of corporate debt
     securities of comparable maturity to the remaining term of the bonds of
     Series 99 or the bonds of Series 100, as applicable.

          "Comparable Treasury Price" means, with respect to any redemption
     date:

               (i) the average of the Reference Treasury Dealer Quotations for
          that redemption date, after excluding the highest and lowest of the
          Reference Treasury Dealer Quotations; or

               (ii) if the Trustee obtains fewer than three Reference Treasury
          Dealer Quotations, the average of all Reference Treasury Dealer
          Quotations so received.

          "Quotation Agent" means the Reference Treasury Dealer appointed by the
     Company.

          "Reference Treasury Dealer" means (1) each of Credit Suisse First
     Boston and Morgan Stanley & Co. Incorporated and their respective
     successors, unless any of them ceases to be a primary U.S. Government
     securities dealer in New York City (a "Primary Treasury Dealer"), in which
     case the Company shall substitute another Primary Treasury Dealer; and (2)
     any other Primary Treasury Dealer selected by the Company.

          "Reference Treasury Dealer Quotations" means, with respect to each
     Reference Treasury Dealer and any redemption date, the average, as
     determined by the Trustee, of the bid and asked prices for the Comparable
     Treasury Issue (expressed in each case as a percentage of its principal
     amount) quoted in writing to the Trustee by that Reference Treasury Dealer
     at 5:00 p.m., New York City time, on the third Business Day preceding that
     redemption date.

     (d) In case the Company shall desire to exercise such right to redeem
and pay off all or any part of such bonds of Series 99 or bonds of Series 100 as
hereinbefore provided, it shall comply with all the terms and provisions of
Article V of the Mortgage applicable thereto, and such redemption shall be made
under and subject to the terms and provisions of Article V and in the manner and
with the effect therein provided, but at the time or times and upon mailing of
notice, all as hereinbefore set forth in this Section 7. No publication of
notice of any redemption of any bonds of Series 99 or bonds of Series 100 shall
be required under Section 5.03(a) of the Mortgage.

                                      -10-
<PAGE>
     SECTION 8. BOOK-ENTRY ONLY SYSTEM. It is intended that the bonds of Series
99 and the bonds of Series 100 be registered so as to participate in the
securities depository system (the "DTC System") with The Depository Trust
Company ("DTC"), as set forth herein. The bonds of Series 99 and the bonds of
Series 100 shall be initially issued in the form of a fully registered bond or
bonds in the name of Cede & Co., or any successor thereto, as nominee for DTC.
The Company and the Trustees are authorized to execute and deliver such letters
to or agreements with DTC as shall be necessary to effectuate the DTC System,
including the Letter of Representations from the Company and the Trustees to DTC
relating to the bonds of Series 99 (the "Series 99 Representation Letter") and a
Letter of Representations from the Company and the Trustee to DTC relating to
the bonds of Series 100 (the "Series 100 Representation Letter" and together
with the Series 99 Representation Letter, the "Representation Letters"). In the
event of any conflict between the terms of the Representation Letters and the
Mortgage, the terms of the Mortgage shall control. DTC may exercise the rights
of a bondholder only in accordance with the terms hereof applicable to the
exercise of such rights.

     With respect to bonds of Series 99 and bonds of Series 100 registered in
the name of DTC or its nominee, the Company and the Trustees shall have no
responsibility or obligation to any broker-dealer, bank or other financial
institution for which DTC holds such bonds 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 bonds (each such
person being herein referred to as an "Indirect Participant"). Without limiting
the immediately preceding sentence, the Company and the Trustees shall have no
responsibility or obligation with respect to:

          (i) the accuracy of the records of DTC, its nominee or any Depository
     Participant with respect to any ownership interest in the bonds of Series
     99 or the bonds of Series 100,

          (ii) the delivery to any Depository Participant or any Indirect
     Participant or any other person, other than a registered owner of a bond of
     Series 99 or a bond of Series 100, of any notice with respect to the bonds
     of Series 99 or the bonds of Series 100, including any notice of
     redemption,

          (iii) the payment to any Depository Participant or Indirect
     Participant or any other person, other than a registered owner of a bond of
     Series 99 or a bond of Series 100, of any amount with respect to principal
     of, redemption premium, if any, on, or interest on, the bonds of Series 99
     or the bonds of Series 100, or

          (iv) any consent given by DTC as registered owner.

So long as certificates for the bonds of Series 99 or the bonds of Series 100
are not issued as hereinafter provided, the Company and the Trustees may treat
DTC or any successor securities depository as, and deem DTC or any successor
securities depository to be, the absolute owner of

                                      -11-
<PAGE>
such bonds for all purposes whatsoever, including, without limitation, (1) the
payment of principal and interest on such bonds, (2) giving notice of matters
(including redemption) with respect to such bonds and (3) registering transfers
with respect to such bonds. While a bond of Series 99 or a bond of Series 100 is
in the DTC System, no person other than DTC or its nominee shall receive a
certificate with respect to such bond.

     In the event that:

          (a) DTC notifies the Company that it is unwilling or unable to
     continue as depositary or if DTC ceases to be a clearing agency registered
     under applicable law and a successor depositary is not appointed by the
     Company within 90 days,

          (b) the Company determines that the beneficial owners of the bonds of
     Series 99 should be able to obtain certificated bonds and so notifies the
     Trustees in writing or

          (c) there shall have occurred and be continuing a completed default or
     any event which after notice or lapse of time or both would be a completed
     default with respect to the bonds of Series 99,

the bonds of Series 99 shall no longer be restricted to being registered in the
name of DTC or its nominee. In the case of clause (a) of the preceding sentence,
the Company may determine that the bonds of Series 99 shall be registered in the
name of and deposited with a successor depository operating a securities
depository system, as may be acceptable to the Company and the Trustees, or such
depository's agent or designee, and if the Company does not appoint a successor
securities depository system within 90 days, then the bonds may be registered in
whatever name or names registered owners of bonds transferring or exchanging
such bonds shall designate, in accordance with the provisions hereof.

     Notwithstanding any other provision of the Mortgage to the contrary, so
long as any bond of Series 99 is registered in the name of DTC or its nominee,
all payments with respect to principal of and interest on such bond and all
notices with respect to such bond shall be made and given, respectively, in the
manner provided in the Series 99 Representation Letter.

     In the event that:

          (a) DTC notifies the Company that it is unwilling or unable to
     continue as depositary or if DTC ceases to be a clearing agency registered
     under applicable law and a successor depositary is not appointed by the
     Company within 90 days,

          (b) the Company determines that the beneficial owners of the bonds of
     Series 100 should be able to obtain certificated bonds and so notifies the
     Trustees in writing or

                                      -12-
<PAGE>
          (c) there shall have occurred and be continuing a completed default or
     any event which after notice or lapse of time or both would be a completed
     default with respect to the bonds of Series 100,

the bonds of Series 100 shall no longer be restricted to being registered in the
name of DTC or its nominee. In the case of clause (a) of the preceding sentence,
the Company may determine that the bonds of Series 100 shall be registered in
the name of and deposited with a successor depository operating a securities
depository system, as may be acceptable to the Company and the Trustees, or such
depository's agent or designee, and if the Company does not appoint a successor
securities depository system within 90 days, then the bonds may be registered in
whatever name or names registered owners of bonds transferring or exchanging
such bonds shall designate, in accordance with the provisions hereof.

     Notwithstanding any other provision of the Mortgage to the contrary, so
long as any bond of Series 100 is registered in the name of DTC or its nominee,
all payments with respect to principal of and interest on such bond and all
notices with respect to such bond shall be made and given, respectively, in the
manner provided in the Series 100 Representation Letter.

     SECTION 9. LEGENDS. So long as the bonds of Series 99 are held by the
Depository Trust Company, such bonds of Series 99 shall, and so long as the
bonds of Series 100 are held by the Depository Trust Company, such bonds of
Series 100 shall, in each case, bear the following legend:

          Unless this bond 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 bond
     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 a person is wrongful inasmuch as the registered owner
     hereof, Cede & Co., has an interest herein.

     SECTION 10. CONFIRMATION OF LIEN. The Company, for the equal and
proportionate benefit and security of the holders of all bonds at any time
issued under the Mortgage, hereby confirms the lien of the Mortgage upon, and
hereby grants, bargains, sells, transfers, assigns, pledges, mortgages, warrants
and conveys unto the Trustees, all property of the Company and all property
hereafter acquired by the Company, other than (in each case) property which, by
virtue of any of the provisions of the Mortgage, is excluded from such lien, and
hereby confirms the title of the Trustees (as set forth in the Mortgage) in and
to all such property. Without in any way limiting or restricting the generality
of the foregoing, there is specifically included within the confirmation of lien
and title hereinabove expressed the property of the Company legally described on
Exhibit A attached hereto and made a part hereof.

                                      -13-
<PAGE>
     SECTION 11. MISCELLANEOUS. The terms and conditions of this Supplemental
Indenture shall be deemed to be a part of the terms and conditions of the
Mortgage for any and all purposes. The Mortgage, as supplemented by said
indentures supplemental thereto dated subsequent to August 1, 1944 and referred
to in the recitals of this Supplemental Indenture, and as further supplemented
by this Supplemental Indenture, is in all respects hereby ratified and
confirmed.

     This Supplemental Indenture shall bind and, subject to the provisions of
Article XIV of the Mortgage, inure to the benefit of the respective successors
and assigns of the parties hereto.

     Although this Supplemental Indenture is dated as of ________ __, 200_, it
shall be effective only from and after the actual time of its execution and
delivery by the Company and the Trustees on the date indicated by their
respective acknowledgments hereto annexed.

     This Supplemental Indenture may be simultaneously executed in any number of
counterparts, and all such counterparts executed and delivered, each as an
original, shall constitute but one and the same instrument.

                                      -14-
<PAGE>
     IN WITNESS WHEREOF, Commonwealth Edison Company has caused this
Supplemental Indenture to be executed in its name by its ______________, and
attested by one of its _________________, and BNY Midwest Trust Company, as
Trustee under the Mortgage, has caused this Supplemental Indenture to be
executed in its name by one of its ______________, and attested by one of its
_________________, and D. G. Donovan, as Co-Trustee under the Mortgage, has
hereunto affixed his signature, all as of the day and year first above written.


                                             COMMONWEALTH EDISON COMPANY


                                             By
                                                Name:
                                                Title:

ATTEST:


     Name:
     Title:

                                             BNY MIDWEST TRUST COMPANY


                                             By
                                                Name:
                                                Title:



ATTEST:


    Name:
    Title:


                                             D. G. DONOVAN

                                      -15-
<PAGE>
STATE OF ILLINOIS)
                        )SS.
COUNTY OF COOK)


     I, ___________, a Notary Public in and for said County, in the State
aforesaid, DO HEREBY CERTIFY that ________________, __________________ of
Commonwealth Edison Company, an Illinois corporation, one of the parties
described in and which executed the foregoing instrument, and _______________, a
__________________ of said corporation, who are both personally known to me to
be the same persons whose names are subscribed to the foregoing instrument as
such _________________ and ________________, respectively, and who are both
personally known to me to be ________________ and a _______________
respectively, of said corporation, appeared before me this day in person and
severally acknowledged that they signed, executed and delivered said instrument
as their free and voluntary act as such ____________ and __________________,
respectively, of said corporation, and as the free and voluntary act of said
corporation, for the uses and purposes therein set forth.

     GIVEN under my hand and notarial seal this ___ day of _____________, A.D.
200_.






                                             --------------
                                             Notary Public

(NOTARIAL SEAL)


My Commission expires __________ __, 20__.

                                      -16-
<PAGE>
STATE OF ILLINOIS)
                             )SS.
COUNTY OF COOK)


     I, ____________, a Notary Public in and for said County, in the State
aforesaid, DO HEREBY CERTIFY that ____________, a ___________ of BNY Midwest
Trust Company, an Illinois trust company, one of the parties described in and
which executed the foregoing instrument, and _____________, a ______________ of
said trust company, who are both personally known to me to be the same persons
whose names are subscribed to the foregoing instrument as such __________ and
____________, respectively, and who are both personally known to me to be a
____________ and a ____________, respectively, of said trust company, appeared
before me this day in person and severally acknowledged that they signed,
executed and delivered said instrument as their free and voluntary act as such
_____________ and _____________, respectively, of said trust company, and as the
free and voluntary act of said trust company, for the uses and purposes therein
set forth.

     GIVEN under my hand and notarial seal this ___ day of _________, A.D. 200_.





                                             ---------------
                                             Notary Public

(NOTARIAL SEAL)


My Commission expires __________ __, 20__.

                                      -17-
<PAGE>
STATE OF ILLINOIS)
                         )SS.
COUNTY OF COOK)


     I, ____________, a Notary Public in and for said County, in the State
aforesaid, DO HEREBY CERTIFY that D. G. DONOVAN, one of the parties described in
and which executed the foregoing instrument, who is personally known to me to be
the same person whose name is subscribed to the foregoing instrument, appeared
before me this day in person and acknowledged that he signed, executed and
delivered said instrument as his free and voluntary act for the uses and
purposes therein set forth.

     GIVEN under my hand and notarial seal this ___ day of _____________, A.D.
200_.






                                             --------------------
                                             Notary Public

(NOTARIAL SEAL)


My Commission expires ____________ __, 20__.

                                      -18-