UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-Q/A

[X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

For the Quarterly Period Ended September 30, 2003

[ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Commission Name of Registrant; State of Incorporation; IRS Employer
File Number Address of Principal Executive Offices; and Identification
Telephone Number Number
- --------------------- --------------------------------------------------------- ------------------------

1-16169 EXELON CORPORATION 23-2990190
(a Pennsylvania corporation)
10 South Dearborn Street - 37th Floor
P.O. Box 805379
Chicago, Illinois 60680-5379
(312) 394-7398
1-1839 COMMONWEALTH EDISON COMPANY 36-0938600
(an Illinois corporation)
10 South Dearborn Street - 37th Floor
P.O. Box 805379
Chicago, Illinois 60680-5379
(312) 394-4321
1-1401 PECO ENERGY COMPANY 23-0970240
(a Pennsylvania corporation)
P.O. Box 8699 2301 Market Street
Philadelphia, Pennsylvania 19101-8699
(215) 841-4000
333-85496 EXELON GENERATION COMPANY, LLC 23-3064219
(a Pennsylvania limited liability company)
300 Exelon Way
Kennett Square, Pennsylvania 19348
(610) 765-6900

Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes [X] No [_].

The number of shares outstanding of each registrant's common stock as of
September 30, 2003 was:

Exelon Corporation Common Stock, without par value 327,021,190
Commonwealth Edison Company Common Stock, $12.50 par value 127,016,483
PECO Energy Company Common Stock, without par value 170,478,507
Exelon Generation Company, LLC not applicable

Indicate by check mark whether the registrant is an accelerated filer (as
defined in Rule 12b-2 of the Act). Exelon Corporation Yes [X] No [ ]
Commonwealth Edison Company, PECO Energy Company and Exelon Generation Company,
LLC Yes [ ] No [X].

TABLE OF CONTENTS

Page No.
--------
FILING FORMAT 3
EXPLANATORY NOTE 3

PART I. FINANCIAL INFORMATION 4
ITEM 4. CONTROLS AND PROCEDURES 4
PART II. OTHER INFORMATION 7
ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K 7

SIGNATURES 10

FILING FORMAT
This combined Form 10-Q/A is being filed separately by Exelon Corporation
(Exelon), Commonwealth Edison Company (ComEd), PECO Energy Company (PECO) and
Exelon Generation Company, LLC (Generation) (Registrants). Information contained
herein relating to any individual registrant has been filed by such registrant
on its own behalf. No registrant makes any representation as to information
relating to any other registrant.

EXPLANATORY NOTE
Exelon, ComEd, PECO and Generation are filing this amendment on Form 10-Q
/A in response to comments received from the staff of the Securities and
Exchange Commission (SEC) in connection with its review of Exelon's Registration
Statement on Form S-3 (File No. 333-108546).

This amendment makes changes to Part I, Item 4. Controls and Procedures to
clarify that each Registrant's access and ability to apply its disclosure
controls and procedures to entities that it does not control or manage are more
limited than subsidiaries that it controls and manages.

Unless otherwise stated, all information contained in this amendment is as
of October 29, 2003, the filing date of our original Quarterly Report on Form
10-Q for the quarter ended September 30, 2003.

PART I. FINANCIAL INFORMATION
ITEM 4. CONTROLS AND PROCEDURES

Exelon

During the third quarter of 2003, Exelon's management, including the
principal executive officer and principal financial officer, evaluated Exelon's
disclosure controls and procedures related to the recording, processing,
summarization and reporting of information in Exelon's periodic reports that it
files with the SEC. These disclosure controls and procedures have been designed
to ensure that (a) material information relating to Exelon, including its
consolidated subsidiaries, is made known to Exelon's management, including these
officers, by other employees of Exelon and its subsidiaries, and (b) this
information is recorded, processed, summarized, evaluated and reported, as
applicable, within the time periods specified in the SEC's rules and forms. Due
to the inherent limitations of control systems, not all misstatements may be
detected. These inherent limitations include the realities that judgments in
decision-making can be faulty and that breakdowns can occur because of simple
error or mistake. Additionally, controls could be circumvented by the individual
acts of some persons or by collusion of two or more people. Exelon's controls
and procedures can only provide reasonable, not absolute, assurance that the
above objectives have been met. Exelon does not control or manage certain of its
unconsolidated entities and thus its access and ability to apply its disclosure
controls and procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

Accordingly, as of September 30, 2003, these officers (principal executive
officer and principal financial officer) concluded that Exelon's disclosure
controls and procedures were effective to accomplish their objectives. Exelon
continually strives to improve its disclosure controls and procedures to enhance
the quality of its financial reporting and to maintain dynamic systems that
change as conditions warrant.

ComEd

During the third quarter of 2003, ComEd's management, including the
principal executive officer and principal financial officer, evaluated ComEd's
disclosure controls and procedures related to the recording, processing,
summarization and reporting of information in ComEd's periodic reports that it
files with the SEC. These disclosure controls and procedures have been designed
to ensure that (a) material information relating to ComEd, including its
consolidated subsidiaries, is made known to ComEd's management, including these
officers, by other employees of ComEd and its subsidiaries, and (b) this
information is recorded, processed, summarized, evaluated and reported, as
applicable, within the time periods specified in the SEC's rules and forms. Due
to the inherent limitations of control systems, not all misstatements may be
detected. These inherent limitations include the realities that judgments in
decision-making can be faulty and that breakdowns can occur because of simple
error or mistake. Additionally, controls could be circumvented by the individual
acts of some persons or by collusion of two or more people. ComEd's controls and
procedures can only provide reasonable, not absolute, assurance that the above
objectives have been met. ComEd does not control or manage certain of its
unconsolidated entities and thus its access and ability to apply its disclosure

controls and procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

Accordingly, as of September 30, 2003, these officers (principal executive
officer and principal financial officer) concluded that ComEd's disclosure
controls and procedures were effective to accomplish their objectives. ComEd
continually strives to improve its disclosure controls and procedures to enhance
the quality of its financial reporting and to maintain dynamic systems that
change as conditions warrant.

PECO
During the third quarter of 2003, PECO's management, including the
principal executive officer and principal financial officer, evaluated PECO's
disclosure controls and procedures related to the recording, processing,
summarization and reporting of information in PECO's periodic reports that it
files with the SEC. These disclosure controls and procedures have been designed
to ensure that (a) material information relating to PECO, including its
consolidated subsidiaries, is made known to PECO's management, including these
officers, by other employees of PECO and its subsidiaries, and (b) this
information is recorded, processed, summarized, evaluated and reported, as
applicable, within the time periods specified in the SEC's rules and forms. Due
to the inherent limitations of control systems, not all misstatements may be
detected. These inherent limitations include the realities that judgments in
decision-making can be faulty and that breakdowns can occur because of simple
error or mistake. Additionally, controls could be circumvented by the individual
acts of some persons or by collusion of two or more people. PECO's controls and
procedures can only provide reasonable, not absolute, assurance that the above
objectives have been met. PECO does not control or manage certain of its
unconsolidated entities and thus its access and ability to apply its disclosure
controls and procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

Accordingly, as of September 30, 2003, these officers (principal executive
officer and principal financial officer) concluded that PECO's disclosure
controls and procedures were effective to accomplish their objectives. PECO
continually strives to improve its disclosure controls and procedures to enhance
the quality of its financial reporting and to maintain dynamic systems that
change as conditions warrant.

Generation

During the third quarter of 2003, Generation's management, including the
principal executive officer and principal financial officer, evaluated
Generation's disclosure controls and procedures related to the recording,
processing, summarization and reporting of information in Generation's periodic
reports that it files with the SEC. These disclosure controls and procedures
have been designed to ensure that (a) material information relating to
Generation, including its consolidated subsidiaries, is made known to
Generation's management, including these officers, by other employees of
Generation and its subsidiaries, and (b) this information is recorded,
processed, summarized, evaluated and reported, as applicable, within the time
periods specified in the SEC's rules and forms. Due to the inherent limitations
of control systems, not all misstatements may be detected. These inherent
limitations include the realities that judgments in decision-making can be
faulty and that breakdowns can occur because of simple error or

mistake. Additionally, controls could be circumvented by the individual acts of
some persons or by collusion of two or more people. Generation's controls and
procedures can only provide reasonable, not absolute, assurance that the above
objectives have been met. Generation does not control or manage certain of its
unconsolidated entities and thus its access and ability to apply its disclosure
controls and procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

Accordingly, as of September 30, 2003, these officers (principal executive
officer and principal financial officer) concluded that Generation's disclosure
controls and procedures were effective to accomplish their objectives.
Generation continually strives to improve its disclosure controls and procedures
to enhance the quality of its financial reporting and to maintain dynamic
systems that change as conditions warrant.

PART II. OTHER INFORMATION
ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K

(a) Exhibits:

10-1 - Retirement and Separation between Exelon Corporation, PECO
Energy Company and Kenneth G. Lawrence, dated as of May 11,
2003. Filed on behalf of PECO.*

10-2 - Purchase and Sale Agreement dated as of October 10, 2003
between British Energy Investment Ltd. and Exelon Generation
Company, LLC relating to the sale and purchase of 100% of the
shares of British Energy US Holdings Inc. Filed on behalf of
Exelon and Generation.*
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Certifications Pursuant to Rule 13a-14(a) and 15d-14(a) of the Securities
and Exchange Act of 1934 as to the Quarterly Report on Form 10-Q/A for the
quarterly period ended September 30, 2003 filed by the following officers
for the following companies:
---------------------------------------------------------------------------

31-1 - Filed by John W. Rowe for Exelon Corporation
31-2 - Filed by Robert S. Shapard for Exelon Corporation
31-3 - Filed by Michael B. Bemis for Commonwealth Edison Company
31-4 - Filed by J. Barry Mitchell for Commonwealth Edison Company
31-5 - Filed by Michael B. Bemis for PECO Energy Company
31-6 - Filed by J. Barry Mitchell for PECO Energy Company
31-7 - Filed by Oliver D. Kingsley Jr. for Exelon Generation Company, LLC
31-8 - Filed by J. Barry Mitchell for Exelon Generation Company, LLC
---------------------------------------------------------------------------

Certifications Pursuant to Section 1350 of Chapter 63 of Title 18 United
States Code (Sarbanes - Oxley Act of 2002) as to the Quarterly Report on
Form 10-Q for the quarterly period ended September 30, 2003 filed by the
following officers for the following companies:*
---------------------------------------------------------------------------

32-1 - Filed by John W. Rowe for Exelon Corporation
32-2 - Filed by Robert S. Shapard for Exelon Corporation
32-3 - Filed by Michael B. Bemis for Commonwealth Edison Company
32-4 - Filed by Robert S. Shapard for Commonwealth Edison Company
32-5 - Filed by Michael B. Bemis for PECO Energy Company
32-6 - Filed by Robert S. Shapard for PECO Energy Company
32-7 - Filed by Oliver D. Kingsley Jr. for Exelon Generation Company,
LLC
32-8 - Filed by Robert S. Shapard for Exelon Generation Company, LLC
---------------------------------------------------------------------------

* Exhibits were filed with the Form 10-Q for the quarterly period ended
September 30, 2003 filed on October 29, 2003 (File No. 1-16169, September
30, 2003 Form 10-Q, Exhibits 10-1 through 32-8).

(b) Reports on Form 8-K:

Exelon, ComEd, PECO and/or Generation filed Current Reports on Form 8-K
during the three months ended September 30, 2003 regarding the following items:

Date of Earliest
Event Reported Description of Item Reported
- ------------------------------------------------------------------------------------------------------------

July 3, 2003 "ITEM 5. OTHER EVENTS" filed for Exelon and Generation regarding
the fact that EBG did not anticipate that the construction of the
Mystic 8 and 9 and Fore River generating stations would achieve
Project Completion as defined in EBG's credit facility by July 11,
2003.

July 29, 2003 "ITEM 5. OTHER EVENTS" filed for Exelon and Generation announcing
that Exelon commenced the process of an orderly transition out of
the ownership of EBG and the projects.

August 6, 2003 "ITEM 5. OTHER EVENTS" filed for Exelon, ComEd, PECO and Generation
reaffirming Exelon's 2003 earnings guidance and announcing
workforce reductions related to The Exelon Way.

August 13, 2003 "ITEM 5. OTHER EVENTS" filed for Exelon and Generation regarding a
note to Exelon's financial community announcing an agreement with
entities controlled by Reservoir to sell 50% of Sithe, after
closing on a call transaction announced in May 2003. In a separate
transaction, Sithe has entered into an agreement with Resevoir to
sell entities holding six U.S. generating facilities and an entity
holding Sithe's Canadian assets.

August 25, 2003 "ITEM 5. OTHER EVENTS" filed for ComEd regarding ComEd's sale of
$250 million of First Mortgage Bonds. "ITEM 7. FINANCIAL
STATEMENTS AND EXHIBITS" including exhibits to ComEd's Form S-3,
Registration No. 333-99363.

August 29, 2003 "ITEM 5. OTHER EVENTS" filed for Exelon and Generation regarding
the fact that the period during which the lenders were precluded
from exercising any remedies resulting from the failure of the EBG
projects to achieve Project Completion had expired. Exelon was
continuing discussions with the lenders regarding the orderly
transition of the projects. Exelon has informed the lenders that
Generation will not provide additional funding to the projects
beyond its existing contractual obligations.

September 12, 2003 "ITEM 5. OTHER EVENTS" filed
for Exelon and ComEd regarding a filing
with the Federal Energy Regulatory
Commission

to seek an adjustment in transmission
rates. The exhibit includes the press
release announcing the filing.

September 24, 2003 "ITEM 5. OTHER EVENTS" filed
for Exelon announcing that it had
finalized the sale of InfraSource, Inc.

September 26, 2003 "ITEM 5. OTHER EVENTS" filed
for Exelon and ComEd announcing that
Exelon is exploring the possibility of
acquiring Illinois Power Company from
Dynegy Inc.
- ------------------------------------------------------------------------------------------------------------

SIGNATURES
- --------------------------------------------------------------------------------

Pursuant to requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

EXELON CORPORATION

/s/ John W. Rowe /s/ Robert S. Shapard
---------------------------- ----------------------------------
JOHN W. ROWE ROBERT S. SHAPARD
Chairman and Executive Vice President and Chief
Chief Executive Officer Financial Officer
(Principal Executive Officer) (Principal Financial Officer)

/s/ Matthew F. Hilzinger
---------------------------------------
MATTHEW F. HILZINGER
Vice President and Corporate Controller
(Principal Accounting Officer)

December 15, 2003

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

Pursuant to requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

COMMONWEALTH EDISON COMPANY

/s/ Michael B. Bemis /s/ J. Barry Mitchell
--------------------------------- -------------------------------
MICHAEL B. BEMIS J. BARRY MITCHELL
President, Exelon Energy Delivery Chief Financial Officer
(Principal Executive Officer) (Principal Financial Officer)

/s/ Duane M. DesParte /s/ Frank M. Clark
------------------------------ ------------------
DUANE M. DESPARTE FRANK M. CLARK
Vice President and Controller, President, ComEd
Exelon Energy Delivery
(Principal Accounting Officer)

December 15, 2003

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

Pursuant to requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

PECO ENERGY COMPANY

/s/ Duane M. DesParte /s/ Denis P. O'Brien
------------------------------ ---------------------
DUANE M. DESPARTE DENIS P. O'BRIEN
Vice President and Controller, President, PECO
Exelon Energy Delivery
(Principal Accounting Officer)

December 15, 2003

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

Pursuant to requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

EXELON GENERATION COMPANY, LLC

/s/ Oliver D. Kingsley Jr. /s/ J. Barry Mitchell
----------------------------- -------------------------------
OLIVER D. KINGSLEY JR. J. BARRY MITCHELL
Chief Executive Officer and Chief Financial Officer
President (Principal Financial Officer)
(Principal Executive Officer)

/s/ Matthew F. Hilzinger
-----------------------------------------------
MATTHEW F. HILZINGER
Vice President and Corporate Controller, Exelon
(Principal Accounting Officer)

December 15, 2003