<PAGE>
 
                                                     Exhibit (4)-35
                                                     Commonwealth Edison Company
                                                     Form 10-K  File No. 1-1839









                          FIRST SUPPLEMENTAL INDENTURE

                         Dated as of September 19, 1995


                                    Between


                          COMMONWEALTH EDISON COMPANY

                                      and

                            WILMINGTON TRUST COMPANY
<PAGE>
 
                                   ARTICLE I
                          DEFINITIONS . . . . . . . . . . . . . . .        2
Section 1.1.  Definition of Terms . . . . . . . . . . . . . . . . .        2
Section 1.2.  Interpretation  . . . . . . . . . . . . . . . . . . .        3

                                   ARTICLE II
                        GENERAL TERMS AND CONDITIONS OF
                           THE NOTES  . . . . . . . . . . . . . . .        3
Section 2.1.  Designation and Principal Amount  . . . . . . . . . .        3
Section 2.2.  Maturity  . . . . . . . . . . . . . . . . . . . . . .        4
Section 2.3.  Form and Payment  . . . . . . . . . . . . . . . . . .        4
Section 2.4.  Global Note . . . . . . . . . . . . . . . . . . . . .        4
Section 2.5.  Interest  . . . . . . . . . . . . . . . . . . . . . .        5

                                  ARTICLE III
                    REDEMPTION OF THE NOTES . . . . . . . . . . . .        6
Section 3.1.  Special Event Redemption  . . . . . . . . . . . . . .        6
Section 3.2.  Optional Redemption by Company  . . . . . . . . . . .        6
Section 3.3.  No Sinking Fund . . . . . . . . . . . . . . . . . . .        7

                                   ARTICLE IV
               EXTENSION OF INTEREST PAYMENT PERIOD . . . . . . . .        7
Section 4.1.  Extension of Interest Payment Period  . . . . . . . .        7
Section 4.2.  Notice of Extension . . . . . . . . . . . . . . . . .        8

                                   ARTICLE V
                             EXPENSES . . . . . . . . . . . . . . .        8
Section 5.1.  Payment of Expenses . . . . . . . . . . . . . . . . .        8

                                   ARTICLE VI
                         SUBORDINATION  . . . . . . . . . . . . . .        9
Section 6.1.  Agreement to Subordinate  . . . . . . . . . . . . . .        9
Section 6.2.  Default on Senior Indebtedness  . . . . . . . . . . .        9
Section 6.3.  Liquidation; Dissolution; Bankruptcy  . . . . . . . .       10
Section 6.4.  Subrogation . . . . . . . . . . . . . . . . . . . . .       11
Section 6.5.  Trustee to Effectuate Subordination . . . . . . . . .       12
Section 6.6.  Notice by the Company . . . . . . . . . . . . . . . .       12
Section 6.7.  Rights of the Trustee; Holders of Senior
              Indebtedness  . . . . . . . . . . . . . . . . . . . .       13
Section 6.8.  Subordination May Not Be Impaired . . . . . . . . . .       14

                                  ARTICLE VII
                   COVENANT TO LIST ON EXCHANGE . . . . . . . . . .       14
Section 7.1.  Listing on Exchange . . . . . . . . . . . . . . . . .       14

                                  ARTICLE VIII
                           FORM OF NOTE . . . . . . . . . . . . . .       15
Section 8.1.  Form of Note  . . . . . . . . . . . . . . . . . . . .       15

                                   ARTICLE IX
                    ORIGINAL ISSUE OF NOTES . . . . . . . . . . . .       21
Section 9.1.  Original Issue of Notes . . . . . . . . . . . . . . .       21

                                      -i-
<PAGE>
 
                                   ARTICLE X
                         MISCELLANEOUS  . . . . . . . . . . . . . .       22
Section 11.1.  Ratification of Indenture  . . . . . . . . . . . . .       22
Section 11.2.  Trustee Not Responsible for Recitals . . . . . . . .       22
Section 11.3.  Governing Law  . . . . . . . . . . . . . . . . . . .       22
Section 11.4.  Separability . . . . . . . . . . . . . . . . . . . .       22
Section 11.5.  Counterparts . . . . . . . . . . . . . . . . . . . .       22




                              -ii-
<PAGE>
 
            THIS FIRST SUPPLEMENTAL INDENTURE, dated as of September 19, 1995
(the "First Supplemental Indenture"), between Commonwealth Edison Company, an
Illinois corporation (the "Company"), and Wilmington Trust Company, not in its
individual capacity but solely as trustee (the "Trustee") under the Indenture
dated as of September 1, 1995 between the Company and the Trustee (the
"Indenture").

                              W I T N E S S E T H:

            WHEREAS, the Company executed and delivered the Indenture to the
Trustee to provide for the future issuance of the Company's unsecured subordi-
nated debt securities, to be issued from time to time in one or more series as
might be determined by the Company under the Indenture, in an unlimited
aggregate principal amount which may be authenticated and delivered as provided
in the Indenture; and

            WHEREAS, pursuant to the terms of the Indenture, the Company desires
to provide for the establishment of a new series of its Debt Securities to be
known as its 8.48% Subordinated Deferrable Interest Notes due September 30, 2035
(the "Notes"), the form and substance of such Notes and the terms, provisions
and conditions thereof to be set forth as provided in the Indenture and this
First Supplemental Indenture; and

            WHEREAS, ComEd Financing I, a Delaware statutory business trust (the
"Trust"), has offered to the public $200 million aggregate stated liquidation
amount of its Trust Originated Preferred Securities (the "Preferred Securities")
and has offered to the Company $6.19 million aggregate stated liquidation amount
of its Trust Originated Common Securities (the "Common Securities"), such
Preferred Securities and Common Securities representing undivided beneficial
interests in the assets of the Trust, and proposes to invest the proceeds from
such offering in $206,190,000 aggregate principal amount of the Notes; and

            WHEREAS, the Company has requested the Trustee to execute and
deliver this First Supplemental Indenture, and all requirements necessary to
make this First Supplemental Indenture a valid instrument, in accordance with
its terms, and to make the Notes, when executed by the Company and authenticated
and delivered by the Trustee, the valid obligations of the Company, have been
performed, and the execution and delivery of this First Supplemental Indenture
has been duly authorized in all respects;

            NOW, THEREFORE, in consideration of the purchase and acceptance of
the Notes by the holders thereof, and for the purpose of setting forth, as
provided in the Indenture, the form and substance of the Notes and the terms,
provisions and conditions
<PAGE>
 
thereof, the Company covenants and agrees with the Trustee as follows:


                                   ARTICLE I
                                  DEFINITIONS

            Section 1.1.  Definition of Terms.  Unless the context otherwise
requires, (a) a term defined in the Indenture has the same meaning when used in
this First Supplemental Indenture, (b)  a term defined anywhere in this First
Supplemental Indenture has the same meaning throughout and (c) the following
terms have the meanings given to them in the Declaration: (i) Clearing Agency;
(ii) Delaware Trustee; (iii) Dissolution Tax Opinion; (iv) No Recognition
Opinion; (v) Preferred Security Certificate; (vi) Property Trustee; (vii) Pro
Rata; (viii) Regular Trustees; (ix) Special Event; and (x) Tax Event.

            In addition, the following terms have the following respective
meanings:

            "Declaration" means the Amended and Restated Declaration of Trust of
      ComEd Financing I, a Delaware business trust, dated as of September 19,
      1995.

            "Dissolution Event" means that, as a result of the occurrence and
      continuation of a Special Event, the Trust is to be dissolved in
      accordance with the Declaration and the Notes held by the Property Trustee
      are to be distributed to the holders of the Trust Securities issued by the
      Trust Pro Rata in accordance with the Declaration.

            "Maturity Date" means the date on which the Notes mature and on
      which the principal shall be due and payable together with all accrued and
      unpaid interest thereon including Compounded Interest and Additional
      Interest, if any.

            "Senior Indebtedness" means (i) any payment in respect of (A)
      indebtedness of the Company for money borrowed and (B) indebtedness
      evidenced by securities, debentures, bonds, notes or other similar
      instruments issued by the Company including, without limitation,
      indebtedness evidenced by securities issued pursuant to the provisions of
      the Mortgage dated July 1, 1923, as supplemented by Supplemental Indenture
      dated August 1, 1944 and subsequent supplemental indentures, between the
      Company, as mortgagor, and Bank of America Illinois and Robert Donahue, as
      trustees; the Indenture dated as of September 1, 1987, as supplemented and
      amended, between the Company and Citibank, N.A., as trustee; the
      Indentures dated April 1, 1949, October 1, 1949, October 1, 1950, October
      1, 1954, January 1, 1958, January 1, 1959 and December 1, 1961, between
      the Company and Harris Trust and Savings Bank, as successor trustee to The
      First National Bank of Chicago; and

                                      -2-
<PAGE>
 
      the Indenture dated February 15, 1973, as supplemented, between the
      Company and LaSalle National Bank, as successor trustee to The First
      National Bank of Chicago; (ii) all capital lease obligations of the
      Company; (iii) all obligations of the Company issued or assumed as the
      deferred purchase price of property, all conditional sale obligations of
      the Company and all obligations of such obligor under any title retention
      agreement (but excluding trade accounts payable arising in the ordinary
      course of business); (iv) all obligations of the Company for reimbursement
      on any letter of credit, banker's acceptance, security purchase facility
      or similar credit transaction; (v) all obligations of the type referred to
      in clauses (i) through (iv) of other persons for the payment of which the
      Company is responsible or liable as obligor, guarantor or otherwise; and
      (vi) all obligations of the type referred to in clauses (i) through (v) of
      other persons secured by any lien on any property or asset of the Company
      (whether or not such obligation is assumed by such obligor), except for
      (1) any such indebtedness that is by its terms subordinated to or pari
      passu with the Notes, as the case may be, including all other debt
      securities and guarantees in respect of those debt securities, issued to
      any other trusts, partnerships or any other entity affiliated with the
      Company which is a financing vehicle of the Company ("Financing Entity")
      in connection with an issuance of preferred securities by such Financing
      Entity or other securities which rank pari passu with, or junior to, the
      Preferred Securities, and (2) any indebtedness between or among the
      Company and its Affiliates.

            Section 1.2.  Interpretation.  Each definition in this First
Supplemental Indenture includes the singular and the plural, and references to
the neuter gender include the masculine and feminine where appropriate.  Terms
which relate to accounting matters shall be interpreted in accordance with
generally accepted accounting principles in effect from time to time. References
to any statute mean such statute as amended at the time and include any
successor legislation.  The word "or" is not exclusive, and the words "herein,"
"hereof" and "hereunder" refer to this First Supplemental Indenture as a whole.
The headings to the Articles and Sections are for convenience of reference and
shall not affect the meaning or interpretation of this First Supplemental
Indenture.  References to Articles and Sections  mean the Articles and Sections
of this First Supplemental Indenture.


                                   ARTICLE II
                        GENERAL TERMS AND CONDITIONS OF
                                   THE NOTES

            Section 2.1.  Designation and Principal Amount.  There is hereby
authorized a series of Debt Securities designated the "8.48% Subordinated
Deferrable Interest Notes due September 30, 2035,"

                                      -3-
<PAGE>
 
limited in aggregate principal amount to $206,190,000, which amount shall be as
set forth in any written order of the Company for the authentication and
delivery of Notes pursuant to Section 2.04 of the Indenture.

            Section 2.2.  Maturity.  The Maturity Date will be September 30,
2035.

            Section 2.3.  Form and Payment.  Except as provided in Section 2.4,
the Notes shall be issued in fully registered certificated form without interest
coupons.  Principal and interest on the Notes issued in certificated form will
be payable, the transfer of such Notes will be registrable and such Notes will
be exchangeable for Notes bearing identical terms and provisions at the office
or agency of the Trustee in Wilmington, Delaware, provided, however, that
payment of interest may be made at the option of the Company by check mailed to
the registered holder at such address as shall appear in the Security Register.
Notwithstanding the foregoing, so long as the registered holder of any Notes is
the Property Trustee, the payment of the principal of and interest (including
Compounded Interest and Additional Interest, if any) on such Notes held by the
Property Trustee will be made at such place and to such account as may be
designated by the Property Trustee.

            Section 2.4.  Global Note.  In connection with a Dissolution Event:

            (a)  the Notes in certificated form may be presented to the Trustee
      by the Property Trustee in exchange for a Global Security in an aggregate
      principal amount equal to the aggregate principal amount of the Notes so
      presented, to be registered in the name of the Depositary, or its nominee,
      and delivered by the Trustee to the Depositary for crediting to the
      accounts of its participants pursuant to the instructions of the Regular
      Trustees.  The Company, upon any such presentation, shall execute a Global
      Security in such aggregate principal amount and deliver the same to the
      Trustee for authentication and delivery in accordance with the Indenture
      and this First Supplemental Indenture.  Payments on the Notes issued as a
      Global security will be made to the Depositary; and

            (b)  if any Preferred Securities are held in non book-entry
      certificated form, the Notes in certificated form may be presented to the
      Trustee by the Property Trustee and any Preferred Security Certificate
      which represents Preferred Securities other than Preferred Securities held
      by the Clearing Agency or its nominee ("Non Book-Entry Preferred
      Securities") will be deemed to represent beneficial interests in Notes
      presented to the Trustee by the Property Trustee having an aggregate
      principal amount equal to the aggregate stated liquidation amount of the
      Non Book-Entry Preferred

                                      -4-
<PAGE>
 
      Securities until such Preferred Security Certificates are presented to the
      Security Registrar for transfer or reissuance at which time such Preferred
      Security Certificates will be cancelled and a Note, registered in the name
      of the holder of the Preferred Security Certificate or the transferee of
      the holder of such Preferred Security Certificate, as the case may be,
      with an aggregate principal amount equal to the aggregate stated
      liquidation amount of the Preferred Security Certificate cancelled, will
      be executed by the Company and delivered to the Trustee for authentication
      and delivery in accordance with the Indenture and this First Supplemental
      Indenture.  On issue of such Notes, Notes with an equivalent aggregate
      principal amount that were presented by the Property Trustee to the
      Trustee will be deemed to have been cancelled.

            Section 2.5.  Interest.  (a)  Each Note will bear interest at the
rate of 8.48% per annum (the "Coupon Rate") from the original date of issuance
until the principal thereof becomes due and payable, and on any overdue
principal and (to the extent that payment of such interest is enforceable under
applicable law) on any overdue installment of interest at the Coupon Rate,
compounded quarterly, payable (subject to the provisions of Article IV)
quarterly in arrears on March 31, June 30, September 30 and December 31 of each
year (each, an "Interest Payment Date"), commencing on September 30, 1995, to
the Person in whose name such Note or any predecessor Note is registered, at the
close of business on the regular record date for such interest installment,
which shall be the close of business on the Business Day next preceding that
Interest Payment Date.  If pursuant to the provisions of Section 2.11(c) of the
Indenture the Notes are no longer represented by a Global Security, the Company
may select a regular record date for such interest installment which shall be
any date at least fifteen days before an Interest Payment Date.

            (b)  The amount of interest payable for any period will be computed
on the basis of a 360-day year of twelve 30-day months.  In the event that any
date on which interest is payable on the Notes 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 (and without any interest or other payment in respect of
any such delay), except that, if such Business Day is in the next succeeding
calendar year, such payment shall be made on the immediately preceding Business
Day, in each case with the same force and effect as if made on such date.  The
amount of interest payable for any period shorter than a full quarterly period
for which interest is computed, will be computed on the basis of the actual
number of days elapsed in such a 90-day quarter.

            (c)  If at any time while the Property Trustee is the holder of any
Notes, the Trust or the Property Trustee is required to pay any taxes, duties,
assessments or governmental charges of whatever nature (other than withholding
taxes) imposed by the United States, or any other taxing authority, then, in any
case,

                                      -5-
<PAGE>
 
the Company will pay as additional interest ("Additional Interest") on the Notes
held by the Property Trustee, such additional amounts as shall be required so
that the net amounts received and retained by the Trust and the Property Trustee
after paying such taxes, duties, assessments or other governmental charges will
be equal to the amounts the Trust and the Property Trustee would have received
had no such taxes, duties, assessments or other government charges been imposed.


                                  ARTICLE III
                            REDEMPTION OF THE NOTES

            Section 3.1.  Special Event Redemption.  If a Tax Event has occurred
and is continuing and:

            (a)  the Company has received a Redemption Tax Opinion; or

            (b)  after receiving a Dissolution Tax Opinion, the Regular Trustees
      shall have been informed by tax counsel rendering the Dissolution Tax
      Opinion that a No Recognition Opinion cannot be delivered to the Trust,

then, notwithstanding Section 3.2(a) but subject to Section 3.2(b), the Company
shall have the right upon not less than 30 days' nor more than 60 days' notice
to the registered holders of the Notes to redeem the Notes, in whole or in part,
for cash within 90 days following the occurrence of such Tax Event (the "90 Day
Period") at a redemption price equal to 100% of the principal amount to be
redeemed plus any accrued and unpaid interest thereon to the date of such
redemption (the "Special Redemption Price"), provided that, if at the time there
is available to the Company the opportunity to eliminate, within the 90 Day
Period, the Tax Event by taking some ministerial action ("Ministerial Action"),
such as filing a form or making an election, or pursuing some other similar
reasonable measure that has no adverse effect on the Company, the Trust or the
Holders of the Trust Securities issued by the Trust, the Company shall pursue
such Ministerial Action in lieu of redemption; and provided further, that the
Company shall have no right to redeem the Notes while the Trust is pursuing any
Ministerial Action pursuant to its obligations under the Declaration.  The
Special Redemption Price shall be paid prior to 12:00 noon, New York time, on
the date of such redemption or at such earlier time as the Company determines
and specifies in the notice of redemption, provided the Company shall deposit
with the Trustee an amount sufficient to pay the Special Redemption Price by
11:00 a.m. on the date such Special Redemption Price is to be paid.

            Section 3.2.  Optional Redemption by Company.  (a)    Subject to the
provisions of Article III of the Indenture and to Section 3.2(b), the Company
shall have the right to redeem the Notes, in whole or in part, from time to
time, on or after

                                      -6-
<PAGE>
 
September 30, 2000, at a redemption price equal to 100% of the principal amount
to be redeemed plus any accrued and unpaid interest thereon to the date of such
redemption (the "Optional Redemption Price").  Any redemption pursuant to this
paragraph will be made upon not less than 30 days' nor more than 60 days' notice
to the registered holder of the Notes, at the Optional Redemption Price.  If the
Notes are only partially redeemed pursuant to this Section 3.2, the Notes will
be redeemed pro rata or by lot or by any other method utilized by the Trustee;
provided, that if at the time of redemption, the Notes are registered as a
Global Security, the Depositary shall determine by lot the principal amount of
such Notes held by each Noteholder to be redeemed.  The Optional Redemption
Price shall be paid prior to 12:00 noon, New York time, on the date of such
redemption or at such earlier time as the Company determines and specifies in
the notice of redemption, provided the Company shall deposit with the Trustee an
amount sufficient to pay the Optional Redemption Price by 11:00 a.m. on the date
such Optional Redemption Price is to be paid.

            (b)  If a partial redemption of the Notes would result in the
delisting of the Preferred Securities issued by the Trust from any national
securities exchange or other organization on which the Preferred Securities are
then listed, the Company shall not be permitted to effect such partial
redemption and may only redeem the Notes in whole.

            Section 3.3.  No Sinking Fund.  The Notes are not entitled to the
benefit of any sinking fund.


                                   ARTICLE IV
                      EXTENSION OF INTEREST PAYMENT PERIOD

            Section 4.1.  Extension of Interest Payment Period.  The Company
shall have the right, at any time and from time to time during the term of the
Notes, to extend the interest payment period of such Notes for up to twenty (20)
consecutive quarters (the "Extended Interest Payment Period").  To the extent
permitted by applicable law, interest, the payment of which has been deferred
because of the extension of the interest payment period pursuant to this Section
4.1, will bear interest compounded quarterly at the Coupon Rate for each quarter
of the Extended Interest Payment Period ("Compounded Interest").  At the end of
the Extended Interest Payment Period, the Company shall pay all interest accrued
and unpaid on the Notes, including any Compounded Interest and Additional
Interest ("Deferred Interest") which shall be payable to the holders of the
Notes in whose names the Notes are registered in the Security Register on the
first record date after the end of the Extended Interest Payment Period.  Before
the termination of any Extended Interest Payment Period, the Company may further
extend such period, provided that such period together with all such further
extensions thereof shall not exceed twenty (20) consecutive quarters or extend
beyond the maturity of the Notes.  Upon the

                                      -7-
<PAGE>
 
termination of any Extended Interest Payment Period and upon the payment of all
Deferred Interest then due, the Company may select a new Extended Interest
Payment Period, subject to the foregoing requirements.  No interest shall be due
and payable during an Extended Interest Payment Period, except at the end
thereof.

            Section 4.2.  Notice of Extension.  (a)  If the Property Trustee is
the only registered holder of the Notes at the time the Company selects an
Extended Interest Payment Period, the Company shall give written notice to both
the Regular Trustees and the Property Trustee of its selection of such Extended
Interest Payment Period one Business Day before the earlier of (i) the next
succeeding date on which Distributions on the Trust Securities issued by the
Trust are payable, or (ii) the date the Trust is required to give notice of the
record or payment date for such Distributions to the New York Stock Exchange or
other applicable self-regulatory organization or to holders of the Preferred
Securities issued by the Trust, but in any event at least one Business Day
before such record date.

            (b)  If the Property Trustee is not the only holder of the Notes at
the time the Company selects an Extended Interest Payment Period, the Company
shall give the holders of the Notes and the Trustee written notice of its
selection of such Extended Interest Payment Period ten (10) Business Days before
the earlier of (i) the next succeeding Interest Payment Date, or (ii) the date
the Company is  required to give notice of the record or payment date of such
interest payment to the New York Stock Exchange or other applicable
self-regulatory organization or to holders of the Notes, but in any event at
least two Business Days before such record date.

            (c)  The quarter in which any notice is given pursuant to paragraphs
(a) or (b) of this Section 4.2 shall be counted as one of the twenty quarters
permitted in the maximum Extended Interest Payment Period permitted under
Section 4.1.


                                   ARTICLE V
                                    EXPENSES

            Section 5.1.  Payment of Expenses.  In connection with the offering,
sale and issuance of the Notes to the Property Trustee in connection with the
sale of the Trust Securities by the Trust, the Company shall:

            (a)  pay all costs and expenses relating to the offering, sale and
      issuance of the Notes, including commissions to the underwriters payable
      pursuant to the Underwriting Agreement and the Pricing Agreement and
      compensation of the Trustee under the Indenture in accordance with the
      provisions of Section 7.06 of the Indenture;

                                      -8-
<PAGE>
 
            (b)  pay all costs and expenses of the Trust (including, but not
      limited to, costs and expenses relating to the organization of the Trust,
      the offering, sale and issuance of the Trust Securities (including
      commissions to the underwriters in connection therewith), the fees and
      expenses of the Property Trustee and the Delaware Trustee, the costs and
      expenses relating to the operation of the Trust, including without
      limitation, costs and expenses of accountants, attorneys, statistical or
      bookkeeping services, expenses for printing and engraving and computing or
      accounting equipment, paying agent(s), registrar(s), transfer agent(s),
      duplicating, travel and telephone and other telecommunications expenses
      and costs and expenses incurred in connection with the acquisition,
      financing, and disposition of Trust assets); and

            (c)  pay any and all taxes (other than United States withholding
      taxes attributable to the Trust or its assets) and all liabilities, costs
      and expenses with respect to such taxes of the Trust.


                                   ARTICLE VI
                                 SUBORDINATION

            Section 6.1.  Agreement to Subordinate.  The Company covenants and
agrees, and each holder of Notes issued hereunder by such holder's acceptance
thereof likewise covenants and agrees, that all Notes shall be issued subject to
the provisions of this Article VI; and each holder of a Note, whether upon
original issue or upon transfer or assignment thereof, accepts and agrees to be
bound by such provisions.

            The payment by the Company of the principal of, premium, if any, and
interest on all Notes issued hereunder shall, to the extent and in the manner
hereinafter set forth, be subordinated and subject in right of payment to the
prior payment in full of all Senior Indebtedness of the Company, whether
outstanding at the date of this First Supplemental Indenture or thereafter
incurred.

            No provision of this Article VI shall prevent the occurrence of any
default or Event of Default hereunder.

            Section 6.2.  Default on Senior Indebtedness.  In the event and
during the continuation of any default by the Company in the payment of
principal, premium, interest or any other payment due on any Senior Indebtedness
of the Company, or in the event that the maturity of any Senior Indebtedness of
the Company has been accelerated because of a default, then, in either case, no
payment shall be made by the Company with respect to the principal (including
redemption and sinking fund payments) of, or premium, if any, or interest on the
Notes.

                                      -9-
<PAGE>
 
            In the event that, notwithstanding the foregoing, any payment shall
be received by the Trustee or any holder when such payment is prohibited by the
preceding paragraph of this Section 6.2, such payment shall be held in trust for
the benefit of, and shall be paid over or delivered to, the holders of Senior
Indebtedness or their respective representatives, or to the trustee or trustees
under any indenture pursuant to which any of such Senior Indebtedness may have
been issued, as their respective interests may appear, but only to the extent
that the holders of the Senior Indebtedness (or their representative or
representatives or a trustee) notify the Trustee within 90 days of such payment
of the amounts then due and owing on the Senior Indebtedness and only the
amounts specified in such notice to the Trustee shall be paid to the holders of
Senior Indebtedness.

            Section 6.3.  Liquidation; Dissolution; Bankruptcy.  Upon any
payment by the Company, or distribution of assets of the Company of any kind or
character, whether in cash, property or securities, to creditors upon any
dissolution or winding-up or liquidation or reorganization of the Company,
whether voluntary or involuntary or in bankruptcy, insolvency, receivership or
other proceedings, all amounts due upon all Senior Indebtedness of the Company
shall first be paid in full, or payment thereof provided for in money in
accordance with its terms, before any payment is made by the Company on account
of the principal (and premium, if any) or interest on the Notes; and upon any
such dissolution or winding-up or liquidation or reorganization, any payment by
the Company, or distribution of assets of the Company of any kind or character,
whether in cash, property or securities, to which the holders of the Notes or
the Trustee would be entitled to receive from the Company, except for the
provisions of this Article VI, shall be paid by the Company or by any receiver,
trustee in bankruptcy, liquidating trustee, agent or other Person making such
payment or distribution, or by the holders of the Notes or by the Trustee under
this Indenture if received by them or it, directly to the holders of Senior
Indebtedness of the Company (pro rata to such holders on the basis of the
respective amounts of Senior Indebtedness held by such holders, as calculated by
the Company) or their representative or representatives, or to the trustee or
trustees under any indenture pursuant to which any instruments evidencing such
Senior Indebtedness may have been issued, as their respective interests may
appear, to the extent necessary to pay such Senior Indebtedness in full, in
money or money's worth, after giving effect to any concurrent payment or
distribution to or for the holders of such Senior Indebtedness, before any
payment or distribution is made to the holders of Notes or to the Trustee.

            In the event that, notwithstanding the foregoing, any payment or
distribution of assets of the Company of any kind or character, whether in cash,
property or securities, prohibited by the foregoing, shall be received by the
Trustee or the holders of the Notes before all Senior Indebtedness of the
Company is paid in full, or provision is made for such payment in money in
accordance

                                      -10-
<PAGE>
 
with its terms, such payment or distribution shall be held in trust for the
benefit of and shall be paid over or delivered to the holders of such Senior
Indebtedness or their representative or representatives, or to the trustee or
trustees under any indenture pursuant to which any instruments evidencing such
Senior Indebtedness may have been issued, as their respective interests may
appear, as calculated by the Company, for application to the payment of all
Senior Indebtedness of the Company remaining unpaid to the extent necessary to
pay such Senior Indebtedness in full in money in accordance with its terms,
after giving effect to any concurrent payment or distribution to or for the
benefit of the holders of such Senior Indebtedness.

            For purposes of this Article VI, the words "cash, property or
securities" shall not be deemed to include shares of stock of the Company as
reorganized or readjusted, or securities of the Company or any other corporation
provided for by a plan of reorganization or readjustment, the payment of which
is subordinated at least to the extent provided in this Article VI with respect
to the Notes to the payment of all Senior Indebtedness of the Company that may
at the time be outstanding, provided that (i) such Senior Indebtedness is
assumed by the new corporation, if any, resulting from any such reorganization
or readjustment, and (ii) the rights of the holders of such Senior Indebtedness
are not, without the consent of such holders, altered by such reorganization or
readjustment.  The consolidation of the Company with, or the merger of the
Company into, another corporation or the liquidation or dissolution of the
Company following the conveyance or transfer of its property as an entirety, or
substantially as an entirety, to another corporation upon the terms and
conditions provided for in Article X of the Indenture shall not be deemed a
dissolution, winding-up, liquidation or reorganization for the purposes of this
Section 6.3 if such other corporation shall, as a part of such consolidation,
merger, conveyance or transfer, comply with the conditions stated in Article X
of the Indenture.  Nothing in Section 6.2 or in this Section 6.3 shall apply to
claims of, or payments to, the Trustee under or pursuant to Section 7.06 of the
Indenture.

            Section 6.4.  Subrogation.  Subject to the payment in full of all
Senior Indebtedness of the Company, the rights of the holders of the Notes shall
be subrogated to the rights of the holders of such Senior Indebtedness to
receive payments or distributions of cash, property or securities of the Company
applicable to such Senior Indebtedness until the principal of (and premium, if
any) and interest on the Notes shall be paid in full; and, for the purposes of
such subrogation, no payments or distributions to the holders for such Senior
Indebtedness of any cash, property or securities to which the holders of the
Notes or the Trustee would be entitled except for the provisions of this Article
VI, and no payment over pursuant to the provisions of this Article VI, to or for
the benefit of the holders of such Senior Indebtedness by holders of the Notes
or the Trustee, shall, as

                                      -11-
<PAGE>
 
between the Company, its creditors other than holders of Senior Indebtedness of
the Company, and the holders of the Notes be deemed to be a payment by the
Company to or on account of such Senior Indebtedness.  It is understood that the
provisions of this Article VI are and are intended solely for the purposes of
defining the relative rights of the holders of the Notes, on the one hand, and
the holders of such Senior Indebtedness on the other hand.

            Nothing contained in this Article VI or elsewhere in this Indenture
or in the Notes is intended to or shall impair, as between the Company, its
creditors other than the holders of Senior Indebtedness of the Company, and the
holders of the Notes, the obligation of the Company which is absolute and
unconditional, to pay to the holders of the Notes the principal of (and premium,
if any) and interest on the Notes as and when the same shall become due and
payable in accordance with their terms, or is intended to or shall affect the
relative rights of the holders of the Notes and creditors of the Company, other
than the holders of Senior Indebtedness of the Company, nor shall anything
herein or therein prevent the Trustee or the holder of any Note from exercising
all remedies otherwise permitted by applicable law upon default under the
Indenture, subject to the rights, if any, under this Article VI of the holders
of such Senior Indebtedness in respect of cash, property or securities of the
Company, received upon the exercise of any such remedy.

            Upon any payment or distribution of assets of the Company referred
to in this Article VI, the Trustee, subject to the provisions of Section 7.01 of
the Indenture, and the holders of the Notes, shall be entitled to rely upon any
order or decree made by any court of competent jurisdiction in which such
dissolution, winding-up, liquidation or reorganization proceedings are pending,
or a certificate of the receiver, trustee in bankruptcy, liquidation trustee,
agent or other Person making such payment or distribution, delivered to the
Trustee or to the holders of the Notes, for the purposes of ascertaining the
Persons entitled to participate in such distribution, the holders of Senior
Indebtedness and other indebtedness of the Company, the amount thereof or
payable thereon, the amount or amounts paid or distributed thereon and all other
facts pertinent thereto or to this Article VI.

            Section 6.5.  Trustee to Effectuate Subordination.  Each holder of
a Note by such holder's acceptance thereof authorizes and directs the Trustee on
such holder's behalf to take such action as may be necessary or appropriate to
effectuate the subordination provided in this Article VI and appoints the
Trustee such holder's attorney-in-fact for any and all such purposes.

            Section 6.6.  Notice by the Company.  The Company shall give prompt
written notice to a Responsible Officer of the Trustee of any fact known to the
Company that would prohibit the making of any payment of monies to or by the
Trustee in respect of the Notes

                                      -12-
<PAGE>
 
pursuant to the provisions of this Article VI.  Notwithstanding the provisions
of this Article VI or any other provision of the Indenture and this First
Supplemental Indenture, the Trustee shall not be charged with knowledge of the
existence of any facts that would prohibit the making of any payment of monies
to or by the Trustee in respect of the Notes pursuant to the provisions of this
Article VI unless and until a Responsible Officer of the Trustee shall have
received written notice thereof at the Principal Office of the Trustee from the
Company or a holder or holders of Senior Indebtedness or from any trustee
therefor; and before the receipt of any such written notice, the Trustee,
subject to the provisions of Section 7.01 of the Indenture, shall be entitled in
all respects to assume that no such facts exist; provided, however, that if the
Trustee shall not have received the notice provided for in this Section 6.6 at
least two Business Days prior to the date upon which by the terms hereof any
money may become payable for any purpose (including, without limitation, the
payment of the principal of (or premium, if any) or interest on any Note), then,
anything herein contained to the contrary notwithstanding, the Trustee shall
have full power and authority to receive such money and to apply the same to the
pur- poses for which they were received, and shall not be affected by any notice
to the contrary that may be received by it within two Business Days prior to
such date.

            The Trustee, subject to the provisions of Section 7.01 of the
Indenture, shall be entitled to rely on the delivery to it of a written notice
by a Person representing himself to be a holder of Senior Indebtedness of the
Company (or a trustee on behalf of such holder) to establish that such notice
has been given by a holder of such Senior indebtedness or a trustee on behalf of
any such holder or holders.  In the event that the Trustee determines in good
faith that further evidence is required with respect to the right of any Person
as a holder of such Senior Indebtedness to participate in any payment or
distribution pursuant to this Article VI, the Trustee may request such Person to
furnish evidence to the reasonable satisfaction of the Trustee as to the amount
of such Senior Indebtedness held by such Person, the extent to which such Person
is entitled to participate in such payment or distribution and any other facts
pertinent to the rights of such Person under this Article VI, and if such
evidence is not furnished, the Trustee may defer any payment to such Person
pending judicial determination as to the right of such Person to receive such
payment.

            Section 6.7.  Rights of the Trustee; Holders of Senior Indebtedness.
The Trustee in its individual capacity shall be entitled to all the rights set
forth in this Article VI in respect of any Senior Indebtedness at any time held
by it, to the same extent as any other holder of Senior Indebtedness, and
nothing in this Indenture shall deprive the Trustee of any of its rights as such
holder.

            With respect to the holders of Senior Indebtedness of the Company,
the Trustee undertakes to perform or to observe only such

                                      -13-
<PAGE>
 
of its covenants and obligations as are specifically set forth in this Article
VI, and no implied covenants or obligations with respect to the holders of such
Senior Indebtedness shall be read into this Indenture against the Trustee.  The
Trustee shall not be deemed to owe any fiduciary duty to the holders of such
Senior Indebtedness and, subject to the provisions of Section 7.01 of the
Indenture, the Trustee shall not be liable to any holder of such Senior
Indebtedness if it shall pay over or deliver to holders of Notes, the Company or
any other Person money or assets to which any holder of such Senior Indebtedness
shall be entitled by virtue of this Article VI or otherwise.

            Section 6.8.  Subordination May Not Be Impaired.  No right of any
present or future holder of any Senior Indebtedness of the Company to enforce
subordination as herein provided shall at any time in any way be prejudiced or
impaired by any act or failure to act on the part of the Company or by any act
or failure to act, in good faith, by any such holder, or by any noncompliance by
the Company with the terms, provisions and covenants of the Indenture,
regardless of any knowledge thereof that any such holder may have or otherwise
be charged with.

            Without in any way limiting the generality of the foregoing
paragraph, the holders of Senior Indebtedness of the Company may, at any time
and from time to time, without the consent of or notice to the Trustee or the
holders of the Notes, without incurring responsibility to the holders of the
Notes and without impairing or releasing the subordination provided in this
Article VI or the obligations hereunder of the holders of the Notes to the
holders of such Senior Indebtedness, do any one or more the following: (i)
change the manner, place or terms of payment or extend the time of payment of,
or renew or alter, such Senior Indebtedness, or otherwise amend or supplement in
any manner such Senior Indebtedness or any instrument evidencing the same or any
agreement under which such Senior Indebtedness is outstanding; (ii) sell,
exchange, release or otherwise deal with any property pledged, mortgaged or
otherwise securing such Senior Indebtedness; (iii) release any Person liable in
any manner for the collection of such Senior Indebtedness; and (iv) exercise or
refrain from exercising any rights against the Company and any other Person.


                                  ARTICLE VII
                          COVENANT TO LIST ON EXCHANGE

            Section 7.1.  Listing on Exchange.  If the Notes are to be issued as
a Global Security in connection with the distribution of the Notes to the
holders of the Preferred Securities issued by the Trust upon a Dissolution
Event, the Company will use its best efforts to list such Notes on the New York
Stock Exchange or on such other exchange as the Preferred Securities are then
listed.

                                      -14-
<PAGE>
 
                                  ARTICLE VIII
                                  FORM OF NOTE

            Section 8.1.  Form of Note.  The Notes and the Trustee's Certificate
of Authentication to be endorsed thereon are to be substantially in the
following forms:

                             (FORM OF FACE OF NOTE)

            [IF THE NOTE IS TO BE A GLOBAL SECURITY, INSERT:  This Note is a
Global Security within the meaning of the Indenture hereinafter referred to and
is registered in the name of a Depository or a nominee of a Depository. This
Note is exchangeable for Notes registered in the name of a person other than the
Depository or its nominee only in the limited circumstances described in the
Indenture, and no transfer of this Note (other than a transfer of this Note as a
whole by the Depository to a nominee of the Depository or by a nominee of the
Depository to the Depository or another nominee of the Depository) may be
registered except in limited circumstances.

            Unless this Note is presented by an authorized representative of The
Depository Trust Company (55 Water Street, New York, New York) to the issuer or
its agent for registration of transfer, exchange or payment, and any Note issued
is registered in the name of Cede & Co. or such other name as requested by an
authorized representative of The Depository Trust Company and any payment hereon
is made to Cede & Co., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY A PERSON IS WRONGFUL since the registered owner hereof, Cede & Co.,
has an interest herein.]




                                      -15-
<PAGE>
 
No.                                                 $

CUSIP No.


                          COMMONWEALTH EDISON COMPANY

                  8.48% SUBORDINATED DEFERRABLE INTEREST NOTE
                             DUE SEPTEMBER 30, 2035


            COMMONWEALTH EDISON COMPANY, an Illinois corporation (the "Company",
which term includes any successor corporation under the Indenture hereinafter
referred to), for value received, hereby promises to pay to _______ or
registered assigns, the principal sum of ____________  Dollars on September 30,
2035, and to pay interest on said principal sum from September 26, 1995 or from
the most recent interest payment date (each such date, an "Interest Payment
Date") to which interest has been paid or duly provided for, quarterly (subject
to deferral as set forth herein) in arrears on March 31, June 30, September 30
and December 31 of each year commencing, September 30, 1995, at the rate of
8.48% per annum until the principal hereof shall have become due and payable,
and on any overdue principal and premium, if any, and (without duplication and
to the extent that payment of such interest is enforceable under applicable law)
on any overdue installment of interest compounded quarterly at the same rate per
annum.  The amount of interest payable on any Interest Payment Date shall be
computed on the basis of a 360-day year of twelve 30-day months.  In the event
that any date on which interest is payable on this Note 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 (and without any interest or other
payment in respect of any such delay), except that, if such Business Day is in
the next succeeding calendar year, such payment shall be made on the immediately
preceding Business Day, in each case with the same force and effect as if made
on such date.  The interest installment so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the person in whose name this Note (or one or more Predecessor
Securities, as defined in said Indenture) is registered at the close of business
on the regular record date for such interest installment [which shall be the
close of business on the Business Day next preceding such Interest Payment
Date.] [IF PURSUANT TO THE PROVISIONS OF Section 2.11(C) OF THE INDENTURE THE
NOTES ARE NO LONGER REPRESENTED BY A GLOBAL SECURITY -- which shall be the close
of business on the ________ day preceding such Interest Payment Date.] Any such
interest installment not punctually paid or duly provided for shall forthwith
cease to be payable to the registered holders on such regular record date, and
may be paid to the person in whose name this Note (or one or more Predecessor
Securities) is registered at the close of business on a special record date to
be fixed by the Trustee for the payment of such defaulted interest,

                                      -16-
<PAGE>
 
notice whereof shall be given to the registered holders of this series of Notes
not less than ten (10) days prior to such special record date, or may be paid at
any time in any other lawful manner not inconsistent with the requirements of
any securities exchange on which the Notes may be listed, and upon such notice
as may be required by such exchange, all as more fully provided in the
Indenture.  The principal of (and premium, if any) and the interest on this Note
shall be payable at the office or agency of the Trustee maintained for that
purpose in Wilmington, Delaware, in any coin or currency of the United States of
America which at the time of payment is legal tender for payment of public and
private debts; provided, however, that payment of interest may be made at the
option of the Company by check mailed to the registered holder at such address
as shall appear in the Security Register.  Notwithstanding the foregoing, so
long as the Holder of this Note is the Property Trustee, the payment of the
principal of (and premium, if any) and interest on this Note will be made at
such place and to such account as may be designated by the Property Trustee.

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

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

            Unless the Certificate of Authentication hereon has been executed by
the Trustee referred to on the reverse side hereof, this Note shall not be
entitled to any benefit under the Indenture or be valid or obligatory for any
purpose.

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

                                      -17-
<PAGE>
 
            IN WITNESS WHEREOF, the Company has caused this instrument to be
executed.


Dated
                                       COMMONWEALTH EDISON COMPANY

                                       By

                                             [Title]

Attest:


By
      Secretary


                    (FORM OF CERTIFICATE OF AUTHENTICATION)

                         CERTIFICATE OF AUTHENTICATION

      This is one of the Notes of the series of Notes described in the within-
mentioned Indenture.



            WILMINGTON TRUST COMPANY,      _____________________
            Not in Its Individual          as Authentication Agent
            Capacity But Solely
            as Trustee

            By                             By
                 Authorized Signatory           Authorized Signatory



                           (FORM OF REVERSE OF NOTE)

            This Note is one of a duly authorized series of Notes of the Company
(herein sometimes referred to as the "Notes"), specified in the Indenture, all
issued or to be issued in one or more series under and pursuant to an Indenture
dated as of September 1, 1995, duly executed and delivered between the Company
and Wilmington Trust Company, not in its individual capacity but solely as
trustee (the "Trustee"), as supplemented by the First Supplemental Indenture
dated as of September 19, 1995 between the Company and the Trustee (the
Indenture as so supplemented, the "Indenture"), to which Indenture and all
indentures supplemental thereto reference is hereby made for a description of
the rights, limitations of rights, obligations, duties and immunities thereunder
of the Trustee, the Company and the holders of the Notes.  By the terms of the
Indenture, the Notes are issuable in

                                      -18-
<PAGE>
 
series which may vary as to amount, date of maturity, rate of interest and in
other respects as in the Indenture provided.  This series of Notes is limited in
aggregate principal amount as specified in said First Supplemental Indenture.

            Because of the occurrence and continuation of a Tax Event, in
certain circumstances this Note will become due and payable at the principal
amount together with any interest accrued thereon (the "Redemption Price"). The
Redemption Price shall be paid prior to 12:00 noon, New York time, on the date
of such redemption or at such earlier time as the Company determines. The
Company shall have the right to redeem this Note at the option of the Company,
without premium or penalty, in whole or in part at any time on or after
September 30, 2000 (an "Optional Redemption"), at a redemption price equal to
100% of the principal amount plus any accrued but unpaid interest to the date of
such redemption (the "Optional Redemption Price").  Any optional redemption
pursuant to this paragraph will be made upon not less than 30 days' nor more
than 60 days' notice, at the Optional Redemption Price.  If the Notes are only
partially redeemed by the Company pursuant to an Optional Redemption, the Notes
will be redeemed pro rata or by lot or by any other method utilized by the
Trustee; provided that if at the time of redemption, the Notes are registered as
a Global Security, the Depositary shall determine by lot the principal amount of
such Notes held by each Noteholder to be redeemed.

            In the event of redemption of this Note in part only, a new Note or
Notes of this series for the unredeemed portion hereof will be issued in the
name of the Holder hereof upon the cancellation hereof.

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

            The Indenture contains provisions permitting the Company and the
Trustee, with the consent of the Holders of not less than a majority in
aggregate principal amount of the Notes of each series affected at the time
outstanding, as defined in the Indenture, to execute supplemental indentures for
the purpose of adding any provisions to or changing in any manner or eliminating
any of the provisions of the Indenture or of any supplemental indenture or of
modifying in any manner the rights of the Holders of the Notes; provided,
however, that no such supplemental indenture shall (i) extend the fixed maturity
of any Notes of any series, or reduce the principal amount thereof, or reduce
the rate or extend the time of payment of interest thereon, or reduce any
premium payable upon the redemption thereof, without the consent of the Holder
of each Note so affected or (ii) reduce the aforesaid percentage of Notes, the
Holders of which are required to consent to any such supplemental indenture,
without the consent of the

                                      -19-
<PAGE>
 
Holders of each Note then outstanding and affected thereby.  The Indenture also
contains provisions permitting the Holders of a majority in aggregate principal
amount of the Notes of any series at the time outstanding affected thereby, on
behalf of all of the Holders of the Notes of such series, to waive any past
default in the performance of any of the covenants contained in the Indenture,
or established pursuant to the Indenture with respect to such series, and its
consequences, except a default in the payment of the principal of or premium, if
any, or interest on any of the Notes of such series.  Any such consent or waiver
by the registered Holder of this Note (unless revoked as provided in the
Indenture) shall be conclusive and binding upon such Holder and upon all future
Holders and owners of this Note and of any Note issued in exchange herefor or in
place hereof (whether by registration of transfer or otherwise), irrespective of
whether or not any 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 premium, if any, and
interest on this Note at the time and place and at the rate and in the money
herein prescribed.

            The Company shall have the right at any time during the term of the
Notes, from time to time to extend the interest payment period of such Notes for
up to twenty (20) consecutive quarters (an "Extended Interest Payment Period"),
at the end of which period the Company shall pay all interest then accrued and
unpaid (together with interest thereon at the rate specified for the Notes to
the extent that payment of such interest is enforceable under applicable law).
Before the termination of any such Extended Interest Payment Period, the Company
may further extend such Extended Interest Payment Period, provided that such
Extended Interest Payment Period together with all such further extensions
thereof shall not exceed twenty (20) consecutive quarters or extend beyond the
maturity of the Notes.  At the termination of any such Extended Interest Payment
Period and upon the payment of all accrued and unpaid interest and any
additional amounts then due, the Company may select a new Extended Interest
Payment Period.

            As provided in the Indenture and subject to certain limitations
therein set forth, this Note is transferable by the registered holder hereof on
the Security Register of the Company, upon surrender of this Note for
registration of transfer at the office or agency of the Trustee in Wilmington,
Delaware accompanied by a written instrument or instruments of transfer in form
satisfactory to the Company or the Trustee duly executed by the registered
holder hereof or his attorney duly authorized in writing, and thereupon one or
more new Notes of authorized denominations and for the same aggregate principal
amount and series will be issued to the designated transferee or transferees. No
service charge will be made for any such transfer, but the

                                      -20-
<PAGE>
 
Company may require payment of a sum sufficient to cover any tax or other
governmental charge payable in relation thereto.

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

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

            [The Notes of this series are issuable only in registered form
without coupons in denominations of $25 and any integral multiple thereof.]
[This Global Security is exchangeable for Notes in definitive form only under
certain limited circumstances set forth in the Indenture.  Notes of this series
so issued are issuable only in registered form without coupons in denominations
of $25 and any integral multiple thereof.] As provided in the Indenture and
subject to certain limitations [herein and] therein set forth, Notes of this
series [so issued] are exchangeable for a like aggregate principal amount of
Notes of this series of a different authorized denomination, as requested by the
Holder surrendering the same.

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


                                   ARTICLE IX
                            ORIGINAL ISSUE OF NOTES

            Section 9.1.  Original Issue of Notes.  Notes in the aggregate
principal amount of $206,190,000 may, upon execution of this First Supplemental
Indenture, be executed by the Company and delivered to the Trustee for
authentication, and the Trustee shall thereupon authenticate and deliver said
Notes to or upon the written order of the Company, signed by its Chairman, its

                                      -21-
<PAGE>
 
President, or any Vice President and its Treasurer or an Assistant Treasurer,
without any further action by the Company.


                                   ARTICLE X
                                 MISCELLANEOUS

            Section 11.1.  Ratification of Indenture.  The Indenture, as
supplemented by this First Supplemental Indenture, is in all respects ratified
and confirmed, and this First Supplemental Indenture shall be deemed part of the
Indenture in the manner and to the extent herein and therein provided.

            Section 11.2.  Trustee Not Responsible for Recitals.  The recitals
herein contained are made by the Company and not by the Trustee, and the Trustee
assumes no responsibility for the correctness thereof.  The Trustee makes no
representation as to the validity or sufficiency of this First Supplemental
Indenture.

            Section 11.3.  Governing Law.  This First Supplemental Indenture and
each Note shall be deemed to be a contract made under the internal laws of the
State of New York, and for all purposes shall be construed in accordance with
the laws of said State.

            Section 11.4.  Separability.  In case any one or more of the
provisions contained in this First Supplemental Indenture or in the Notes shall
for any reason be held to be invalid, illegal or unenforceable in any respect,
such invalidity, illegality or unenforceability shall not affect any other
provisions of this First Supplemental Indenture or of the Notes, but this First
Supplemental Indenture and the Notes shall be construed as if such invalid or
illegal or unenforceable provision had never been contained herein or therein.

            Section 11.5.  Counterparts.  This First Supplemental Indenture may
be executed in any number of counterparts each of which shall be an original;
but such counterparts shall together constitute but one and the same instrument.



                                      -22-
<PAGE>
 
            IN WITNESS WHEREOF, the parties hereto have caused this First
Supplemental Indenture to be duly executed, and their respective corporate seals
to be hereunto affixed and attested, on the date or dates indicated in the
acknowledgements and as of the day and year first above written.


                                       COMMONWEALTH EDISON COMPANY


                                       By:  John C. Bukovski
                                            --------------------------
                                            Vice President


[Corporate Seal]

Attest:

      David A Scholz
      -----------------------
      Secretary


                                       WILMINGTON TRUST COMPANY,
                                       Not in Its Individual Capacity But
                                       Solely as Trustee


                                       By:  W. Chris Sponenberg
                                            --------------------------
                                            Title: Financial Services
                                            Officer

[Corporate Seal]

Attest: Patricia A. Evans
        -----------------------

      Title: Financial Services Officer
<PAGE>
 
STATE OF ILLINOIS )
COUNTY OF COOK    ) ss:


            On the 25th day of September, 1995, before me personally came John
C. Bukovski, to me known, who, being by me duly sworn, did depose and say that
he is a Vice President of COMMONWEALTH EDISON COMPANY, one of the corporations
described in and which executed the above instrument; that he knows the
corporate seal of said corporation; that the seal affixed to the said instrument
is such corporate seal; that it was so affixed by authority of the Board of
Directors of said corporation, and that he signed his name thereto by like
authority.


                                       NOTARY PUBLIC
                                       Lupe Luna
                                       --------------------
[seal]                                 Commission expires
                                       November 9, 1997

STATE OF DELAWARE   )
COUNTY OF New Castle):


            On the 22nd day of September, 1995, before me personally came W.
Chris Sponenberg, to me known, who, being by me duly sworn, did depose and say
that he is the Financial Service Officer of WILMINGTON TRUST COMPANY, one of the
corporations described in and which executed the above instrument; that he knows
the corporate seal of said corporation; that the seal affixed to the said
instrument is such corporate seal; that it was so affixed by authority of the
Board of Directors of said corporation, and that he signed his name thereto by
like authority.

                                       NOTARY PUBLIC
                                       Kathleen A. Pedelini
                                       --------------------
[seal]                                 Commission expires
                                       October 31, 1998