<TABLE> <S> <C>

<PAGE>

<ARTICLE> UT
<LEGEND> This schedule contains summary financial information extracted from
the Consolidated Balance Sheet and Statement of Consolidated Capitalization as
of September 30, 1999 and the related Statement of Consolidated Operations,
Retained Earnings and Cash Flow for the nine months ended September 30, 1999
and is qualified in its entirety by reference to such financial statements.
</LEGEND>
<CIK>      0000022606
<NAME>     Commonwealth Edison Company
<MULTIPLIER> 1,000

<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1999
<PERIOD-START>                             JAN-01-1999
<PERIOD-END>                               SEP-30-1999
<BOOK-VALUE>                                  PER-BOOK
<TOTAL-NET-UTILITY-PLANT>                   13,615,698
<OTHER-PROPERTY-AND-INVEST>                  2,454,837
<TOTAL-CURRENT-ASSETS>                       3,126,868
<TOTAL-DEFERRED-CHARGES>                             0<F1>
<OTHER-ASSETS>                               4,564,775
<TOTAL-ASSETS>                              23,762,178
<COMMON>                                     2,677,979
<CAPITAL-SURPLUS-PAID-IN>                    2,207,264
<RETAINED-EARNINGS>                            408,520
<TOTAL-COMMON-STOCKHOLDERS-EQ>               5,270,861<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                     18,820
<LONG-TERM-DEBT-NET>                         7,049,748<F3>
<SHORT-TERM-NOTES>                                   0<F1>
<LONG-TERM-NOTES-PAYABLE>                            0<F3>
<COMMERCIAL-PAPER-OBLIGATIONS>                       0<F1>
<LONG-TERM-DEBT-CURRENT-PORT>                  876,387
<PREFERRED-STOCK-CURRENT>                       69,475
<CAPITAL-LEASE-OBLIGATIONS>                    213,725
<LEASES-CURRENT>                               158,291
<OTHER-ITEMS-CAPITAL-AND-LIAB>              10,104,871<F4>
<TOT-CAPITALIZATION-AND-LIAB>               23,762,178
<GROSS-OPERATING-REVENUE>                    5,271,794
<INCOME-TAX-EXPENSE>                           302,684<F5>
<OTHER-OPERATING-EXPENSES>                   4,040,785
<TOTAL-OPERATING-EXPENSES>                   4,341,421
<OPERATING-INCOME-LOSS>                        930,373
<OTHER-INCOME-NET>                             (3,066)<F5><F6><F7>
<INCOME-BEFORE-INTEREST-EXPEN>                 925,259
<TOTAL-INTEREST-EXPENSE>                       413,824
<NET-INCOME>                                   511,435
<PREFERRED-STOCK-DIVIDENDS>                     20,170
<EARNINGS-AVAILABLE-FOR-COMM>                  491,265
<COMMON-STOCK-DIVIDENDS>                       256,695
<TOTAL-INTEREST-ON-BONDS>                            0<F8>
<CASH-FLOW-OPERATIONS>                       1,432,210
<EPS-BASIC>                                          0<F8>
<EPS-DILUTED>                                        0<F8>
<FN>
<F1> This item is not disclosed as a separate line item on the Consolidated
     Balance Sheet.
<F2> Includes a deduction of $10,365 thousand for treasury stock.
<F3> $3,700,953 thousand of notes, guaranteed senior notes and transitional
     trust notes are included in LONG-TERM-DEBT-NET.
<F4> Includes $350,000 thousand of Company-obligated mandatorily redeemable
     preferred securities of subsidiary trusts holding solely the Company's
     subordinated debt securities.
<F5> Income tax expense of $2,048 thousand related to nonoperating activities
     is included in INCOME-TAX-EXPENSE.
<F6> Includes $22,283 thousand of provision for preferred securities dividends
     of subsidiary trusts holding solely the Company's subordinated debt
     securities.
<F7> Includes an extraordinary loss of $27,579 thousand related to the early
     redemption of long-term debt during the first nine months of 1999.
<F8> This item is not disclosed as a separate line item on the Statement of
     Consolidated Operations.
</FN>


</TABLE>