Document:

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                          PECO ENERGY TRANSITION TRUST,

                                     Issuer

                                       and

                              THE BANK OF NEW YORK,

                                  Bond Trustee

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

                                SERIES SUPPLEMENT

                            Dated as of March 1, 2001

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

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

<PAGE>

                                TABLE OF CONTENTS
                                -----------------

                                                                            Page
                                                                            ----

SECTION 1.  Definitions......................................................  3
SECTION 2.  Designation; Series Issuance Dates...............................  5
SECTION 3.  Initial Principal Amount; Bond Rate; Special Payment Date;
            Expected Final Payment Date; Series Termination Date; Class
            Termination Date.................................................  5
SECTION 4.  Payment Dates; Expected Amortization Schedule or Principal;
            Interest; Overcollateralization Amount; Monthly Allocated
            Balances.........................................................  5
SECTION 5.  Authorized Initial Denominations.................................  7
SECTION 6.  Redemption.......................................................  7
SECTION 7.  Credit Enhancement...............................................  8
SECTION 8.  Delivery and Payment for the Series 2000-A Transition Bonds;
            Form of the Series 2000-A Transition Bonds.......................  8
SECTION 09. Indemnity Amounts................................................  8
SECTION 10. Confirmation of Indenture........................................  8
SECTION 11. Counterparts.....................................................  8
SECTION 12. Governing Law....................................................  8
SECTION 13. Issuer Obligation................................................  9

Schedule A  Expected Amortization Schedule
Schedule B  Monthly Allocated Balances

Exhibit A   Form of Transition Bond

                                       i

<PAGE>

                    SERIES SUPPLEMENT dated as of March 1, 2001 (this
               "Supplement"), by and between PECO ENERGY TRANSITION TRUST, a
               Delaware statutory business trust (the "Issuer"), and THE BANK OF
               NEW YORK, a New York banking corporation (the "Bond Trustee"), as
               Bond Trustee under the Indenture dated as of March 1, 1999,
               between the Issuer and the Bond Trustee, as amended and
               supplemented by the Series Supplement thereto dated as of May 2,
               2000, between the Issuer and the Bond Trustee (the "Indenture").

                              PRELIMINARY STATEMENT

         Section 9.01 of the Indenture provides, among other things, that the
Issuer and the Bond Trustee may at any time and from time to time enter into one
or more indentures supplemental to the Indenture for the purposes of authorizing
the issuance by the Issuer of a Series of Transition Bonds and specifying the
terms thereof and for modifying certain provisions of the Indenture. The Issuer
has duly authorized the execution and delivery of this Supplement and the
creation of a Series of Transition Bonds with an initial aggregate principal
amount of $805,460,000 to be known as the Issuer's Transition Bonds, Series
2001-A (the "Series 2001-A Transition Bonds"). All acts and all things necessary
to make the Series 2001-A Transition Bonds, when duly executed by the Issuer and
authenticated by the Bond Trustee as provided in the Indenture and this
Supplement and issued by the Issuer, the valid, binding and legal obligations of
the Issuer and to make this Supplement a valid and enforceable supplement to the
Indenture have been done, performed and fulfilled and the execution and delivery
hereof have been in all respects duly and lawfully authorized. The Issuer and
the Bond Trustee are executing and delivering this Supplement in order to
provide for the Series 2001-A Transition Bonds.

         In order to secure the payment of principal of and interest on the
Series 2001-A Transition Bonds, and to further secure the payment of principal
of and interest on the Series 1999-A Bonds issued on March 25, 1999, and the
Series 2000-A Bonds issued on May 2, 2000, in each case issued and to be issued

<PAGE>

under the Indenture and/or any Series Supplement, the Issuer hereby Grants, and
confirms its prior Grants on March 25, 1999 and May 2, 2000, in connection with
the issuance of the Series 1999-A Bonds and the Series 2000-A Bonds,
respectively, to the Bond Trustee as trustee for the benefit of the Holders of
the Transition Bonds from time to time issued and outstanding, all of the
Issuer's right, title and interest in and to (a) the Intangible Transition
Property transferred by the Seller to the Issuer from time to time pursuant to
the Sale Agreement and all proceeds thereof, (b) the Sale Agreement except for
Section 5.01 thereof solely to the extent such Section provides for
indemnification of the Issuer, (c) all Bills of Sale delivered by the Seller
pursuant to the Sale Agreement, (d) the Servicing Agreement except for Section
5.02(b) thereof solely to the extent such Section provides for indemnification
of the Issuer, (e) the Collection Account and all amounts on deposit therein
from time to time, (f) all Swap Agreements with respect to the Transition Bonds,
(g) all other property of whatever kind owned from time to time by the Issuer
including all accounts, accounts receivable, chattel paper and general
intangibles, (h) all present and future claims, demands, causes and choses in
action in respect of any or all of the foregoing and (i) all payments on or
under and all proceeds of every kind and nature whatsoever in respect of any or
all of the foregoing, including all proceeds of the conversion, voluntary or
involuntary, into cash or other liquid property, all cash proceeds, accounts,
accounts receivable, general intangibles, notes, drafts, acceptances, chattel
paper, checks, deposit accounts, insurance proceeds, condemnation awards, rights
to payment of any and every kind, and other forms of obligations and
receivables, instruments and other property which at any time constitute all or
part of or are included in the proceeds of any of the foregoing (collectively,
the "Collateral").

         To have and to hold in trust to secure the payment of principal of and
premium, if any, and interest on, and any other amounts (including all fees,
expenses, counsel fees and other amounts due and owing to the Bond Trustee)
owing in respect of, the Transition Bonds equally and ratably without prejudice,
preference, priority or distinction, except as expressly provided in the

                                       2

<PAGE>

Indenture or any Series Supplement and to secure performance by the Issuer of
all of the Issuer's obligations under the Indenture and all Series Supplements
with respect to the Transition Bonds, all as provided in the Indenture.

         The Bond Trustee, as trustee on behalf of the Holders of the Transition
Bonds, acknowledges such Grant, accepts the trusts hereunder in accordance with
the provisions hereof and agrees to perform its duties required in the Indenture
and this Supplement.

         SECTION 1. Definitions. (a) Article One of the Indenture provides that
the meanings of certain defined terms used in the Indenture shall, when applied
to the Transition Bonds of a particular Series, be as defined in Article One but
with such additional provisions as are specified in the related Series
Supplement. With respect to the Series 2001-A Transition Bonds, the following
definitions shall apply:

         "Adjustment Date" shall mean initially each August 12th, until August
12, 2009, and commencing on February 14, 2010, such date and the 14th day of
each month thereafter until the Series Termination Date.

         "Authorized Initial Denominations" shall mean $1,000 and integral
multiples thereof.

         "Bond Rate" has the meaning set forth in Section 3 of this Supplement.

         "Calculation Date" means initially each May 14th, until May 14, 2010,
and commencing on January 14, 2010, such date and the 14th day of each month
thereafter until the Series Termination Date.

         "Class Termination Date" means, with respect to Class A-1 of the Series
2001-A Transition Bonds, the termination date therefor, as specified in Section
3 of this Supplement.

         "Expected Amortization Schedule" means Schedule A to this Supplement.

                                       3

<PAGE>

         "Expected Final Payment Date" means, with respect to Class A-1 of the
Series 2001-A Transition Bonds, the expected final payment date therefor, as
specified in Section 3 of this Supplement.

         "Interest Accrual Period" means, with respect to any Payment Date, the
period from and including the preceding Payment Date (or, in the case of the
first Payment Date, from and including the Series Issuance Date) to and
excluding such Payment Date.

         "Monthly Allocated Interest Balance" has the meaning set forth in
Section 4(e) of this Supplement.

         "Monthly Allocated Principal Balance" has the meaning set forth in
Section 4(e) of this Supplement.

         "Overcollateralization Amount" has the meaning set forth in Section
4(d) of this Supplement.

         "Payment Date" has the meaning set forth in Section 4(a) of this
Supplement.

         "Record Date" shall mean, with respect to any Payment Date, the close
of business on the day prior to such Payment Date.

         "Series Issuance Date" has the meaning set forth in Section 2(b) of
this Supplement.

         "Series Termination Date" has the meaning set forth in Section 3 of
this Supplement.

         "Servicing Fee Rate" shall mean 0.25% per annum so long as ITC Charges
are included in electric bills otherwise sent to Customers or, if ITC Charges
are not included in such bills, 1.50% per annum.

         "Special Payment Date" means December 31, 2010.

         (b) All terms used in this Supplement that are defined in the
Indenture, either directly or by reference therein, have the meanings assigned
to them therein, except to the extent such terms are defined or modified in this
Supplement or the context clearly requires otherwise.

                                       4

<PAGE>

         SECTION 2. Designation; Series Issuance Dates. (a) Designation. The
Series 2001-A Transition Bonds shall be designated generally as the Issuer's
Transition Bonds, Series 2001-A and further denominated as Class A-1.

         (b) Series Issuance Date. The Series 2001-A Transition Bonds that are
authenticated and delivered by the Bond Trustee to or upon the order of the
Issuer on March 1, 2001 (the "Series Issuance Date") shall have as their date of
authentication March 1, 2001. Each other Series 2001-A Transition Bond shall be
dated the date of its authentication.

         SECTION 3. Initial Principal Amount; Bond Rate; Special Payment Date;
Expected Final Payment Date; Series Termination Date; Class Termination Dates.
The Transition Bonds of Class A-1 of the Series 2001-A Transition Bonds shall
have the initial principal amount, bear interest at the rate per annum and shall
have Special Payment Date, Expected Final Payment Date and Class Termination
Date as set forth below:

<TABLE>
<CAPTION>
               Initial
              Principal       Bond            Special              Expected Final                 Class
  Class        Amount         Rate         Payment Date             Payment Date             Termination Date
               ------         ----         ------------             ------------             ----------------
<S>          <C>               <C>          <C>                     <C>                        <C>
   A-1       805,460,000      6.52%      December 31,2010         September 1, 2010         December 31, 2010

</TABLE>

         The Bond Rate for Class A-1 shall be computed on the basis of a 360-day
year of twelve 30-day months.

         SECTION 4. Payment Dates; Expected Amortization Schedule for Principal;
Interest; Overcollateralization Amount; Monthly Allocated Balances. (a) Payment
Dates. The Payment Dates for the Class A-1 Series 2001-A Transition Bonds are
March 1 and September 1 of each year and the Special Payment Date or, if any
such date is not a Business Day, the next succeeding Business Day, commencing on
September 1, 2001 and continuing until the earlier of repayment of such Class in
full and the Class Termination Date.

         (b) Expected Amortization Schedule for Principal. Unless an Event of
Default shall have occurred and be continuing and the unpaid principal amount of

                                       5
<PAGE>

all Series of Transition Bonds has been declared to be due and payable together
with accrued and unpaid interest thereon, on each Payment Date, the Bond Trustee
shall distribute to the Series 2001-A Transition Bondholders of record as of the
related Record Date amounts payable in respect of the Series 2001-A Transition
Bonds pursuant to Section 8.02(e) of the Indenture as principal, in accordance
with the Expected Amortization Schedule. Available funds in the Series 2001-A
Subaccount will be allocated, to the extent funds are available, to the holders
of the Series 2001-A Transition Bonds, Class A-1, until this Class is retired in
full. Other than in the event of an acceleration of payments following an Event
of Default or a redemption, in no event shall a principal payment pursuant to
this Section 4(b) on Class A-1 on a Payment Date be greater than the amount that
reduces the Outstanding Amount of such Class of Series 2001-A Transition Bonds
to the amount specified in the Expected Amortization Schedule which is attached
as Schedule A hereto for such Class and Payment Date.

         (c) Interest. Interest will be payable on the Class A-1 Series 2001-A
Transition Bonds on each Payment Date in an amount equal to one-half (one-third
minus one day, in the case of the Special Payment Date) of the product of (i)
the applicable Bond Rate and (ii) the Outstanding Amount of the related Class of
Transition Bonds as of the close of business on the preceding Payment Date after
giving effect to all payments of principal made to the holders of the Class A-1
Series 2001-A Transition Bonds on such preceding Payment Date; and provided,
further, that with respect to the initial Payment Date or, if no payment has yet
been made, interest on the outstanding principal balance will accrue from and
including the Series Issuance Date to, but excluding, the following Payment
Date.

         (d) Overcollateralization Amount. The Overcollateralization Amount for
the Series 2001-A Transition Bonds shall be $100,000,000.

         (e) Monthly Allocated Balances. The Monthly Allocated Interest Balance
and Monthly Allocated Principal Balance for any Monthly Allocation Date and the
Series 2001-A Transition Bonds shall be as set forth in Schedule B hereto.

                                       6
<PAGE>

         Not later than each Schedule Revision Date, the Issuer shall deliver to
the Bond Trustee replacement Schedules A and B hereto, adjusted to reflect the
event giving rise to such Schedule Revision Date and setting forth the Expected
Amortization Schedule for each Payment Date and the Monthly Allocated Interest
Balance and Monthly Allocated Principal Balance for each Monthly Allocation
Date; provided, however, that no such replacement schedules shall be required if
the event giving rise to such Schedule Revision Date is a redemption of the
Series 2001-A Transition Bonds in whole.

         SECTION 5. Authorized Initial Denominations. The Series 2001-A
Transition Bonds shall be issuable in the Authorized Initial Denominations.

         SECTION 6. Redemption. (a) Mandatory Redemption. The Series 2001-A
Transition Bonds shall not be subject to mandatory redemption except as provided
in Section 10.02 of the Indenture in the event that the Issuer receives
Liquidated Damages. If the Issuer receives Liquidated Damages from the Seller as
a result of a breach of a representation and warranty under the Sale Agreement
which relates to one or more of the Qualified Rate Orders, but not all of the
Qualified Rate Orders, then (i) only the Affected Transition Bonds will be
redeemed and (ii) the Redemption Price shall be equal to the then outstanding
principal amount of the Affected Transition Bonds as of the Liquidated Damages
Redemption Date plus accrued interest to such Redemption Date.

         (b) Optional Redemption. The Series 2001-A Transition Bonds shall not
be subject to optional redemption by the Issuer except that the Series 2001-A
Transition Bonds may be redeemed in whole at a Redemption Price equal to the
principal amount thereof plus interest at the applicable Bond Rate accrued to
the Redemption Date on any Payment Date on which the Outstanding Amount thereof
(after giving effect to payments that would otherwise be made on such Payment
Date) has been reduced to less than or equal to 5% of the initial principal
balance thereof. Notwithstanding Section 10.01 of the Indenture, with respect to
an optional redemption pursuant to this Section 6(b), the Issuer shall deposit

                                       7

<PAGE>

with the Bond Trustee the Redemption Price of the Transition Bonds to be
redeemed plus accrued interest thereon to the Redemption Date on or prior to the
date that notice of such redemption is furnished.

         SECTION 7. Credit Enhancement. No credit enhancement (other than the
Overcollateralization Amount) is provided for the Series 2001-A Transition
Bonds.

         SECTION 8. Delivery and Payment for the Series 2001-A Transition Bonds;
Form of the Series 2001-A Transition Bonds. The Bond Trustee shall deliver the
Series 2001-A Transition Bonds to the Issuer when authenticated in accordance
with Section 2.02 of the Indenture. The Series 2001-A Transition Bonds of each
Class shall be in the form of Exhibit A.

         SECTION 9. Indemnity Amounts. Notwithstanding the definition of
Indemnity Amounts in Section 1.01(a) of the Indenture, Indemnity Amounts means
any amounts paid by the Seller or the Servicer to the Bond Trustee, for itself
or on behalf of the Transition Bondholders, pursuant to Section 5.01(b),
5.0l(c)(ii) and 5.01(e) of the Sale Agreement or Section 5.02(b) of the
Servicing Agreement or by the Issuer to the Bond Trustee pursuant to Section
6.07 of this Indenture; provided, however, that Indemnity Amounts shall exclude
Liquidated Damages paid pursuant to Section 5.01(c)(ii) of the Sale Agreement.

         SECTION 10. Confirmation of Indenture. As supplemented by this
Supplement, the Indenture is in all respects ratified and confirmed and the
Indenture, as so supplemented by this Supplement, shall be read, taken, and
construed as one and the same instrument.

         SECTION 11. Counterparts. This Supplement may be executed in any number
of counterparts, each of which so executed shall be deemed to be an original,
but all of such counterparts shall together constitute but one and the same
instrument.

         SECTION 12. Governing Law. This Supplement shall be construed in
accordance with the laws of the Commonwealth of Pennsylvania, without reference

                                       8

<PAGE>

to its conflict of law provisions, and the obligations, rights and remedies of
the parties hereunder shall be determined in accordance with such laws.

         SECTION 13. Issuer Obligation. No recourse may be taken, directly or
indirectly, with respect to the obligations of the Issuer or the Bond Trustee on
the Transition Bonds or under this Supplement or any certificate or other
writing delivered in connection herewith or therewith, against (i) any owner of
a beneficial interest in the Issuer or (ii) any partner, owner, beneficiary,
agent, officer, director or employee of the Bond Trustee, any holder of a
beneficial interest in the Issuer or the Bond Trustee or of any successor or
assign of the Bond Trustee, except as any such Person may have expressly agreed
(it being understood that none of the Bond Trustee's obligations are in its
individual capacity).

                                       9
<PAGE>

         IN WITNESS WHEREOF, the Issuer and the Bond Trustee have caused this
Supplement to be duly executed by their respective officers thereunto duly
authorized as of the first day of the month and year first above written.

                                  PECO ENERGY TRANSITION TRUST,

                                  by  First Union Trust Company,
                                      National Association, not
                                      in its individual capacity
                                      but solely as Issuer
                                      Trustee, Delaware Trustee
                                      and Independent Trustee

                                  by /s/ Michael W. Orendorf
                                     ---------------------------
                                     Name:  Michael W. Orendorf
                                     Title: Vice President

                                  THE BANK OF NEW YORK, not in
                                  its individual capacity but
                                  solely as Bond Trustee on
                                  behalf of the Transition
                                  Bondholders,

                                  by /s/ Thomas J. Provenzano
                                     ---------------------------
                                     Name:  Thomas J. Provenzano
                                     Title: Vice President

                                       10

<PAGE>

                                                                      SCHEDULE A

                         Expected Amortization Schedule
                         -------------------------------

                          Outstanding Principal Balance

--------------------------------------------------------------------------------
Payment Date                                            Series 2001-A
--------------------------------------------------------------------------------

Series Issuance Date                                     805,460,000

September 1, 2001                                        805,460,000

March 1, 2002                                            805,460,000

September 1, 2002                                        805,460,000

March 1, 2003                                            805,460,000

September 1, 2003                                        805,460,000

March 1, 2004                                            805,460,000

September 1, 2004                                        805,460,000

March 1, 2005                                            805,460,000

September 1, 2005                                        805,460,000

March 1, 2006                                            805,460,000

September 1, 2006                                        805,460,000

March 1, 2007                                            805,460,000

September 1, 2007                                        805,460,000

March 1, 2008                                            805,460,000

September 1, 2008                                        805,460,000

March 1, 2009                                            805,460,000

September 1, 2009                                        805,460,000

March 1, 2010                                            403,783,303

September 1, 2010                                                  0

<PAGE>

                                                                      SCHEDULE B

                           Monthly Allocated Balances

                                 Monthly Allocated            Monthly Allocated
Monthly Allocation Date           Interest Balance            Principal Balance
-----------------------          ------------------           -----------------

April 1, 2001................         5,218,497                             0
May 1, 2001..................         9,602,441                             0
June 1, 2001.................        13,505,563                             0
July 1, 2001.................        17,379,054                             0
August 1, 2001...............        21,575,662                             0
September 1, 2001............        26,257,996                             0
October 1, 2001..............         4,301,908                             0
November 1, 2001.............         8,763,876                             0
December 1, 2001.............        12,949,543                             0
January 1, 2002..............        17,053,380                             0
February 1, 2002.............        21,534,271                             0
March 1, 2002................        26,257,996                             0
April 1, 2002................         4,554,311                             0
May 1, 2002..................         8,886,115                             0
June 1, 2002.................        12,922,435                             0
July 1, 2002.................        16,960,616                             0
August 1, 2002...............        21,348,103                             0
September 1, 2002............        26,257,996                             0
October 1, 2002..............         5,523,345                             0
November 1, 2002.............        10,132,289                             0
December 1, 2002.............        14,120,908                             0
January 1, 2003..............        17,955,757                             0
February 1, 2003.............        22,030,336                             0
March 1, 2003................        26,257,996                             0
April 1, 2003................         4,548,667                             0
May 1, 2003..................         8,877,960                             0
June 1, 2003.................        12,913,356                             0
July 1, 2003.................        16,956,336                             0
August 1, 2003...............        21,348,466                             0
September 1, 2003............        26,257,996                             0
October 1, 2003..............         4,633,575                             0

<PAGE>

                                 Monthly Allocated            Monthly Allocated
Monthly Allocation Date           Interest Balance            Principal Balance
-----------------------          ------------------           -----------------

November 1, 2003.............         9,196,624                             0
December 1, 2003.............        13,388,617                             0
January 1, 2004..............        17,476,370                             0
February 1, 2004.............        21,802,391                             0
March 1, 2004................        26,257,996                             0
April 1, 2004................         4,552,230                             0
May 1, 2004..................         8,882,482                             0
June 1, 2004.................        12,917,852                             0
July 1, 2004.................        16,958,812                             0
August 1, 2004...............        21,348,897                             0
September 1, 2004............        26,257,996                             0
October 1, 2004..............         4,403,436                             0
November 1, 2004.............         8,936,275                             0
December 1, 2004.............        13,155,991                             0
January 1, 2005..............        17,282,853                             0
February 1, 2005.............        21,686,354                             0
March 1, 2005................        26,257,996                             0
April 1, 2005................         4,549,488                             0
May 1, 2005..................         8,879,099                             0
June 1, 2005.................        12,914,567                             0
July 1, 2005.................        16,956,706                             0
August 1, 2005...............        21,348,144                             0
September 1, 2005............        26,257,996                             0
October 1, 2005..............         4,770,891                             0
November 1, 2005.............         9,245,862                             0
December 1, 2005.............        13,295,855                             0
January 1, 2006..............        17,233,052                             0
February 1, 2006.............        21,569,015                             0
March 1, 2006................        26,257,996                             0
April 1, 2006................         4,545,809                             0
May 1, 2006..................         8,878,589                             0
June 1, 2006.................        12,916,764                             0
July 1, 2006.................        16,955,524                             0
August 1, 2006...............        21,344,240                             0

                                       2
<PAGE>

                                 Monthly Allocated            Monthly Allocated
Monthly Allocation Date           Interest Balance            Principal Balance
-----------------------          ------------------           -----------------

September 1, 2006............       26,257,996                             0
October 1, 2006..............        4,653,842                             0
November 1, 2006.............        9,195,782                             0
December 1, 2006.............       13,357,259                             0
January 1, 2007..............       17,414,724                             0
February 1, 2007.............       21,746,472                             0
March 1, 2007................       26,257,996                             0
April 1, 2007................        4,563,350                             0
May 1, 2007..................        8,898,744                             0
June 1, 2007.................       12,935,042                             0
July 1, 2007.................       16,964,037                             0
August 1, 2007...............       21,344,006                             0
September 1, 2007............       26,257,996                             0
October 1, 2007..............        5,129,428                             0
November 1, 2007.............        9,697,830                             0
December 1, 2007.............       13,746,003                             0
January 1, 2008..............       17,661,708                             0
February 1, 2008.............       21,860,697                             0
March 1, 2008................       26,257,996                             0
April 1, 2008................        4,563,963                             0
May 1, 2008..................        8,899,532                             0
June 1, 2008.................       12,935,753                             0
July 1, 2008.................       16,963,481                             0
August 1, 2008...............       21,342,697                             0
September 1, 2008............       26,257,996                             0
October 1, 2008..............        4,773,943                             0
November 1, 2008.............        9,322,614                             0
December 1, 2008.............       13,448,801                             0
January 1, 2009..............       17,462,022                             0
February 1, 2009.............       21,764,143                             0
March 1, 2009................       26,257,996                             0
April 1, 2009................        4,564,998                             0
May 1, 2009..................        8,900,540                             0
June 1, 2009.................       12,936,581                             0

                                       3

<PAGE>

                                 Monthly Allocated            Monthly Allocated
Monthly Allocation Date           Interest Balance            Principal Balance
-----------------------          ------------------           -----------------

July 1, 2009.................        16,964,445                            0
August 1, 2009...............        21,343,547                            0
September 1, 2009............        26,257,996                            0
October 1, 2009..............         4,749,414                   72,653,263
November 1, 2009.............         9,295,735                  142,199,742
December 1, 2009.............        13,426,928                  205,395,876
January 1, 2010..............        17,446,750                  266,888,337
February 1,2010..............        21,756,343                  332,813,515
March 1, 2010................        26,257,996                  401,676,697
April 1, 2010................         2,288,482                   70,198,844
May 1, 2010..................         4,461,927                  136,868,935
June 1, 2010.................         6,485,225                  198,933,284
July 1, 2010.................         8,504,414                  260,871,608
August 1, 2010...............        10,699,683                  328,211,143
September 1, 2010............        13,163,336                  403,783,303

                                       4

<PAGE>

                                                  Exhibit A to Series Supplement

REGISTERED                                                                 $ ___
No. ___

                       SEE REVERSE FOR CERTAIN DEFINITIONS

                                                                  CUSIP NO. ___

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

         THE PRINCIPAL OF THIS CLASS A-1 TRANSITION BOND WILL BE PAID IN
INSTALMENTS AS SET FORTH HEREIN. ACCORDINGLY, THE OUTSTANDING PRINCIPAL AMOUNT
OF THIS CLASS A-1 TRANSITION BOND AT ANY TIME MAY BE LESS THAN THE AMOUNT SHOWN
ON THE FACE HEREOF.

                          PECO ENERGY TRANSITION TRUST

                   TRANSITION BONDS, SERIES 2001-A, Class A-1.

   Bond                        Original Principal            Expected Final
   Rate                              Amount                   Payment Date
   ----                        ------------------            --------------
      %                             $

         PECO Energy Transition Trust, a statutory business trust organized and
existing under the laws of the State of Delaware (herein referred to as the
"Issuer"), for value received, hereby promises to pay to the Registered Holder
hereof, or registered assigns, the Original Principal Amount shown above in
instalments on the Payment Dates and in the amounts specified on the reverse

<PAGE>

hereof or, if less, the amounts determined pursuant to Section 8.02(e) of the
Indenture, in each year, commencing on the date determined as provided on the
reverse hereof and ending on or before the Class A-1 Termination Date, to pay
the entire unpaid principal hereof on the Class A-1 Termination Date and to pay
interest, at the Bond Rate shown above, on each March 1 and September 1 and the
Special Payment Date or if any such day is not a Business Day, the next
succeeding Business Day, commencing on September 1, 2001 and continuing until
the earlier of the payment of the principal hereof and the Class A-1 Termination
Date (each a "Payment Date"), on the principal amount of this Class A-1
Transition Bond outstanding from time to time. Interest on this Class A-1
Transition Bond will accrue for each Payment Date from the most recent Payment
Date on which interest has been paid to but excluding such Payment Date or, if
no interest has yet been paid, from March 1, 2001. Interest will be computed on
the basis of a 360-day year of twelve 30-day months. Such principal of and
interest on this Class A-1 Transition Bond shall be paid in the manner specified
on the reverse hereof.

         The principal of and interest on this Class A-1 Transition Bond are
payable in such coin or currency of the United States of America as at the time
of payment is legal tender for payment of public and private debts. All payments
made by the Issuer with respect to this Class A-1 Transition Bond shall be
applied first to interest due and payable on this Class A-1 Transition Bond as
provided above and then to the unpaid principal of and premium, if any, on this
Class A-1 Transition Bond, all in the manner set forth in Section 8.02(e) of the
Indenture.

         Reference is made to the further provisions of this Class A-1
Transition Bond set forth on the reverse hereof, which shall have the same
effect as though fully set forth on the face of this Class A-1 Transition Bond.

         Unless the certificate of authentication hereon has been executed by
the Bond Trustee whose name appears below by manual signature, this Class A-1
Transition Bond shall not be entitled to any benefit under the Indenture
referred to on the reverse hereof, or be valid or obligatory for any purpose.

                                       2

<PAGE>

         IN WITNESS WHEREOF, the Issuer has caused this instrument to be signed,
manually or in facsimile, by an Authorized Officer of the Issuer Trustee.

Date:

                                       PECO ENERGY TRANSITION TRUST,

                                            by First Union Trust Company,
                                               National Association, not in
                                               its individual capacity but
                                               solely as Issuer Trustee,

                                             by
                                                ---------------------------
                                                Name:
                                                Title:

                                       3

<PAGE>

                  BOND TRUSTEE'S CERTIFICATE OF AUTHENTICATION

Dated:  March 1, 2001

         This is one of the Class A-1 Transition Bonds of the Series 2001-A
Transition Bonds, designated above and referred to in the within-mentioned
Indenture.

                                      THE BANK OF NEWYORK, not in its
                                      individual capacity but solely as
                                      Bond Trustee on behalf of the
                                      Transition Bondholders,

                                        by
                                          --------------------------
                                          Authorized Signatory

                                       4

<PAGE>

                          [REVERSE OF TRANSITION BOND]

         This Series 2001-A, Class A-1 Transition Bond is one of a duly
authorized issue of Transition Bonds of the Issuer, designated as its Transition
Bonds (herein called the "Transition Bonds"), issued and to be issued in one or
more Series, which Series are issuable in one or more Classes, and this Series
2001-A Transition Bond, in which this Class A-1 Transition Bond represents an
interest, consists of one Class, the Class A-1 Transition Bonds (herein called
the "Class A-1 Transition Bonds"), all issued and to be issued under an
indenture dated as of March 1, 1999, and a series supplement thereto dated as of
March 1, 2001 (such series supplement, as supplemented or amended, the
"Supplement" and, collectively with such indenture, as supplemented or amended,
the "Indenture"), each between the Issuer and The Bank of New York, as Bond
Trustee (the "Bond Trustee", which term includes any successor bond trustee
under the Indenture), to which Indenture and all indentures supplemental thereto
reference is hereby made for a statement of the Collateral property pledged, the
nature and extent of the security, the respective rights, obligations and
immunities thereunder of the Issuer, the Bond Trustee and the Holders of the
Transition Bonds and the terms and conditions under which additional Transition
Bonds may be issued. All terms used in this Class A-1 Transition Bond that are
defined in the Indenture, as supplemented or amended, shall have the meanings
assigned to them in the Indenture.

         The Class A-1 Transition Bonds of the Series 2001-A Transition Bonds
and any other Series of Transition Bonds issued by the Issuer are and will be
equally and ratably secured by the Collateral pledged as security therefor as
provided in the Indenture.

         The principal of this Class A-1 Transition Bond shall be payable on
each Payment Date only to the extent that amounts in the Collection Account are
available therefor, and only until the outstanding principal balance thereof on
such Payment Date (after giving effect to all payments of principal, if any,
made on such Payment Date) has been reduced to the principal balance specified
in the Expected Amortization Schedule which is attached to the Supplement as
Schedule A, unless payable earlier either because (i) an Event of Default shall
have occurred and be continuing and the Bond Trustee or the Holders of

                                       5

<PAGE>

Transition Bonds representing not less than a majority of the Outstanding Amount
of the Transition Bonds of all Series have declared the Transition Bonds to be
immediately due and payable in accordance with Section 5.02 of the Indenture,
(ii) the Issuer, at its option, shall have called for the redemption of the
Series 2001-A Transition Bonds in whole or from time to time in part pursuant to
Section 10.01 of the Indenture, (iii) the Issuer shall have called for the
redemption of the Series 2001-A Transition Bonds pursuant to Section 10.02 of
the Indenture if the Seller is required to pay Liquidated Damages pursuant to
Section 5.01(d) of the Sale Agreement or (iv) the Issuer, at its option, shall
have called for the redemption of the Series 2001-A Transition Bonds in whole
pursuant to Section 6(b) of the Supplement. However, actual principal payments
may be made in lesser than expected amounts and at later than expected times as
determined pursuant to Section 8.02(e) of the Indenture. The entire unpaid
principal amount of this Class A-1 Transition Bond shall be due and payable on
the earlier of the Class A-1 Termination Date hereof and the Redemption Date, if
any, herefor. Notwithstanding the foregoing, the entire unpaid principal amount
of the Transition Bonds shall be due and payable, if not then previously paid,
on the date on which an Event of Default shall have occurred and be continuing
and the Bond Trustee or the Holders of the Transition Bonds representing not
less than a majority of the Outstanding Amount of the Transition Bonds have
declared the Transition Bonds to be immediately due and payable in the manner
provided in Section 5.02 of the Indenture. All principal payments on the Class
A-1 Transition Bonds shall be made pro rata to the Class A-1 Transition
Bondholders entitled thereto based on the respective principal amounts of the
Class A-1 Transition Bonds held by them.

         Payments of interest on this Class A-1 Transition Bond due and payable
on each Payment Date, together with the instalment of principal or premium, if
any, due on this Class A-1 Transition Bond on such Payment Date shall be made by
check mailed first-class, postage prepaid, to the Person whose name appears as
the Registered Holder of this Class A-1 Transition Bond (or one or more
Predecessor Transition Bonds) in the Transition Bond Register as of the close of
business on the Record Date or in such other manner as may be provided in the
Supplement, except that with respect to Class A-1 Transition Bonds registered on
the Record Date in the name of a Clearing Agency, payments will be made by wire
transfer in immediately available funds to the account designated by such
Clearing Agency and except for the final

                                       6

<PAGE>

instalment of principal and premium, if any, payable with respect to this Class
A-1 Transition Bond on a Payment Date which shall be payable as provided below.
Such checks shall be mailed to the Person entitled thereto at the address of
such Person as it appears in the Transition Bond Register as of the applicable
Record Date without requiring that this Class A-1 Transition Bond be submitted
for notation of payment. Any reduction in the principal amount of this Class A-1
Transition Bond (or any one or more Predecessor Transition Bonds) effected by
any payments made on any Payment Date shall be binding upon all future Holders
of this Class A-1 Transition Bond and of any Class A-1 Transition Bond issued
upon the registration of transfer hereof or in exchange hereof or in lieu
hereof, whether or not noted hereon. If funds are expected to be available, as
provided in the Indenture, for payment in full of the then remaining unpaid
principal amount of this Class A-1 Transition Bond on a Payment Date, then the
Bond Trustee, in the name of and on behalf of the Issuer, will notify the Person
who was the Registered Holder hereof as of the second preceding Record Date to
such Payment Date by notice mailed no later than fivedays prior to such final
Payment Date and shall specify that such final instalment will be payable to the
Registered Holder hereof as of the Record Date immediately preceding such final
Payment Date and only upon presentation and surrender of this Class A-1
Transition Bond and shall specify the place where this Class A-1 Transition Bond
may be presented and surrendered for payment of such instalment.

         The Issuer shall pay interest on overdue instalments of interest on
this Class A-1 Transition Bond at the Class A-1 Bond Rate to the extent lawful.

         As provided in the Indenture, the Class A-1 Transition Bonds may be
redeemed, in whole or from time to time in part, at the option of the Issuer on
any Redemption Date at the Redemption Price. In addition, as provided in the
Indenture, if the Seller is required to pay Liquidated Damages pursuant to
Section 5.01(d) of the Sale Agreement, the Issuer will be required to redeem all
outstanding Series of Transition Bonds, including the Class A-1 Transition
Bonds, on the Liquidated Damages Redemption Date.

         As provided in the Indenture and subject to certain limitations set
forth therein, the transfer of this Class A-1 Transition Bond may be registered
in the Transition Bond Register upon surrender of this Class A-1

                                       7

<PAGE>

Transition Bond for registration of transfer at the office or agency designated
by the Issuer pursuant to the Indenture, duly endorsed by, or accompanied by a
written instrument of transfer in form satisfactory to the Bond Trustee duly
executed by the Holder hereof or his attorney duly authorized in writing, with
such signature guaranteed by an Eligible Guarantor Institution, and thereupon
one or more new Class A-1 Transition Bonds of any Authorized Initial
Denominations and in the same aggregate initial principal amount will be issued
to the designated transferee or transferees. No service charge will be charged
for any registration of transfer or exchange of this Class A-1 Transition Bond,
but the transferor may be required to pay a sum sufficient to cover any tax or
other governmental charge that may be imposed in connection with any
registration of transfer or exchange.

         Each Class A-1 Transition Bondholder, by acceptance of a Class A-1
Transition Bond, covenants and agrees that no recourse may be taken, directly or
indirectly, with respect to the obligations of the Issuer or the Bond Trustee on
the Class A-1 Transition Bonds or under the Indenture or any certificate or
other writing delivered in connection herewith or therewith, against (i) any
owner of a beneficial interest in the Issuer or (ii) any partner, owner,
beneficiary, agent, officer, director or employee of the Bond Trustee, any
holder of a beneficial interest in the Issuer or the Bond Trustee or of any
successor or assign of the Bond Trustee, except as any such Person may have
expressly agreed (it being understood that all of the Bond Trustee's obligations
are in its individual capacity).

         Prior to the due presentment for registration of transfer of this Class
A-1 Transition Bond, the Issuer, the Bond Trustee and any agent of the Issuer or
the Bond Trustee may treat the Person in whose name this Class A-1 Transition
Bond is registered (as of the day of determination) as the owner hereof for the
purpose of receiving payments of principal of and premium, if any, and interest
on this Class A-1 Transition Bond and for all other purposes whatsoever, whether
or not this Class A-1 Transition Bond be overdue, and neither the Issuer, the
Bond Trustee nor any such agent shall be affected by notice to the contrary.

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Issuer and the rights of the Holders of the Transition Bonds under the Indenture

                                       8

<PAGE>

at any time by the Issuer with the consent of the Holders of Transition Bonds
representing a majority of the Outstanding Amount of all Transition Bonds at the
time Outstanding of each Series or Class to be affected. The Indenture also
contains provisions permitting the Holders of Transition Bonds representing
specified percentages of the Outstanding Amount of the Transition Bonds of all
Series, on behalf of the Holders of all the Transition Bonds, to waive
compliance by the Issuer with certain provisions of the Indenture and certain
past defaults under the Indenture and their consequences. Any such consent or
waiver by the Holder of this Class A-1 Transition Bond (or any one of more
Predecessor Transition Bonds) shall be conclusive and binding upon such Holder
and upon all future Holders of this Class A-1 Transition Bond and of any Class
A-1 Transition Bond issued upon the registration of transfer hereof or in
exchange hereof or in lieu hereof whether or not notation of such consent or
waiver is made upon this Class A-1 Transition Bond. The Indenture also permits
the Bond Trustee to amend or waive certain terms and conditions set forth in the
Indenture without the consent of Holders of the Transition Bonds issued
thereunder.

         The term "Issuer" as used in this Class A-1 Transition Bond includes
any successor to the Issuer under the Indenture.

         The Issuer is permitted by the Indenture, under certain circumstances,
to merge or consolidate, subject to the rights of the Bond Trustee and the
Holders of Transition Bonds under the Indenture.

         The Class A-1 Transition Bonds are issuable only in registered form in
Authorized Initial Denominations as provided in the Indenture and the
Supplement, subject to certain limitations therein set forth.

         This Class A-1 Transition Bond, the Indenture and the Supplement shall
be construed in accordance with the laws of the Commonwealth of Pennsylvania,
without reference to its conflict of law provisions, and the obligations, rights
and remedies of the parties hereunder and thereunder shall be determined in
accordance with such laws.

         No reference herein to the Indenture and no provision of this Class A-1
Transition Bond or of the Indenture shall alter or impair the obligation of the
Issuer, which is absolute and unconditional, to pay the principal of and
interest on this Class A-1 Transition Bond at the times, place, and rate, and in
the coin or currency herein prescribed.

                                       9

<PAGE>

                                   ASSIGNMENT

Social Security or taxpayer I.D. or other identifying number of assignee

________________________

                  FOR VALUE RECEIVED, the undersigned hereby sells, assigns and
transfers unto__________________________________________________________________

________________________________________________________________________________
                         (name and address of assignee)

the within Class A-1 Transition Bond and all rights thereunder, and hereby
irrevocably constitutes and appoints____________________________________________

_______________________________________________________________________________,
attorney, to transfer said Class A-1 Transition Bond on the books kept for
registration thereof, with full power of substitution in the premises.

Dated:____________________             ________________________________________*
                                       Signature Guaranteed:

__________________________             _________________________________________

-------------------
         * NOTE: The signature to this assignment must correspond with the name
of the registered owner as it appears on the face of the within Class A-1
Transition Bond in every particular, without alteration, enlargement or any
change whatsoever.

                                       10<PAGE>

                           AMENDMENT dated as of March 1, 2001 to the INTANGIBLE
                  TRANSITION PROPERTY SALE AGREEMENT dated as of March 25, 1999,
                  as amended and restated as of May 2, 2000 (the "Existing
                  Agreement"), between PECO ENERGY TRANSITION TRUST, a Delaware
                  business trust (the "Issuer"), and PECO ENERGY COMPANY, a
                  Pennsylvania corporation, and its successors in interest to
                  the extent permitted under the Existing Agreement, as Seller
                  (the "Seller").

                  WHEREAS the Issuer and the Seller desire to amend the Existing
Agreement in connection with the issuance by the Issuer of the Series 2001-A
Transition Bonds.

                  NOW, THEREFORE, in consideration of the premises and the
mutual covenants herein contained and intending to be legally bound hereby, the
parties hereto agree as follows:

                  SECTION 1. Definitions. Capitalized terms used but not defined
in this Amendment shall have the meanings assigned to them in the Existing
Agreement.

                  SECTION 2. Amendment of Existing Agreement. The first two
sentences of Article III of the Existing Agreement are hereby amended to read in
their entirety as follows:

         "As of the Initial Transfer Date, as of any Subsequent Transfer Date
         and as of any other date on which the Issuer issues any Series of
         Transition Bonds, as applicable, the Seller makes the following
         representations and warranties on which the Issuer has relied and will
         rely in acquiring Transferred Intangible Transition Property and
         issuing any Series of Transition Bonds. The representations and
         warranties shall survive the sale of Transferred Intangible Transition
         Property to the Issuer and the pledge thereof to the Bond Trustee
         pursuant to the Indenture and the issuance by the Issuer of any Series
         of Transition Bonds."

                  SECTION 3. Agreement. Except as specifically amended hereby,
the Existing Agreement shall continue in full force and effect in accordance
with the provisions thereof as in existence on the date hereof. On and after the
date hereof, any reference to the Existing Agreement shall mean the Existing
Agreement as amended hereby.
<PAGE>

                  SECTION 4. Separate Counterparts. This Amendment may be
executed by the parties hereto in separate counterparts, each of which when so
executed and delivered shall be an original, but all such counterparts shall
together constitute but one and the same instrument.

                  SECTION 5. Governing Law. This Amendment shall be construed in
accordance with the laws of the Commonwealth of Pennsylvania, without reference
to its conflict of law provisions, and the obligations, rights and remedies of
the parties hereunder shall be determined in accordance with such laws.

                  SECTION 6. Limitation of Liability of Issuer Trustee.
Notwithstanding anything contained herein to the contrary, this Amendment has
been countersigned by First Union Trust Company, National Association, not in
its individual capacity but solely in its capacity as Issuer Trustee of the
Issuer and in no event shall First Union Trust Company, National Association, in
its individual capacity have any liability for warranties, covenants, agreements
or other obligations of the Issuer hereunder or in any of the certificates,
notices or agreements delivered pursuant hereto, as to all of which recourse
shall be had solely to the assets of the Issuer. For all purposes of this
Amendment, in the performance of its duties or obligations hereunder or in the
performance of any duties or obligations of the Issuer hereunder, the Issuer
Trustee shall be subject to, and entitled to the benefits of, the terms and
provisions of Articles VI, VII, VIII and IX of the Trust Agreement.

<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have caused this
Amendment to be duly executed by their respective officers as of the day and
year first above written.

                                       PECO ENERGY TRANSITION TRUST,

                                         by First Union Trust
                                            Company, National
                                            Association, not in its
                                            individual capacity but
                                            solely as Issuer Trustee
                                            on behalf of the Trust,

                                         by: /s/ Michael W. Orendorf
                                             ----------------------------------
                                             Title: Vice President

                                      PECO ENERGY COMPANY, Seller

                                         by: /s/ J. Barry Mitchell
                                             ----------------------------------
                                             Title: Vice President and Treasurer

Acknowledged and Accepted:

THE BANK OF NEW YORK, not
in its individual capacity
but solely as Bond Trustee
on behalf of the Transition
Bondholders,

  by /s/ Thomas J. Provenzano
     --------------------------------
     Title: Vice President

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