<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, 1997 and the related Statements of Consolidated Income, 
Retained Earnings and Cash Flows for the nine months ended September 30, 1997
and is qualified in its entirety by reference to such financial statements. 
</LEGEND>
<CIK>      0000918040
<NAME>     Unicom Corporation
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               SEP-30-1997
<BOOK-VALUE>                                  PER-BOOK 
<TOTAL-NET-UTILITY-PLANT>                   16,935,815
<OTHER-PROPERTY-AND-INVEST>                  2,140,875
<TOTAL-CURRENT-ASSETS>                       1,433,267
<TOTAL-DEFERRED-CHARGES>                             0<F1>
<OTHER-ASSETS>                               2,965,565
<TOTAL-ASSETS>                              23,475,522
<COMMON>                                     4,936,918
<CAPITAL-SURPLUS-PAID-IN>                            0
<RETAINED-EARNINGS>                          1,277,979
<TOTAL-COMMON-STOCKHOLDERS-EQ>               6,211,539<F2>
<PREFERRED-MANDATORY>                          177,899<F3>
<PREFERRED>                                    507,053<F3>
<LONG-TERM-DEBT-NET>                         5,811,166<F4>
<SHORT-TERM-NOTES>                               7,750
<LONG-TERM-NOTES-PAYABLE>                            0<F4>
<COMMERCIAL-PAPER-OBLIGATIONS>                  35,000
<LONG-TERM-DEBT-CURRENT-PORT>                  484,077
<PREFERRED-STOCK-CURRENT>                       30,688<F3>
<CAPITAL-LEASE-OBLIGATIONS>                    497,259
<LEASES-CURRENT>                               140,960
<OTHER-ITEMS-CAPITAL-AND-LIAB>               9,572,131<F5>
<TOT-CAPITALIZATION-AND-LIAB>               23,475,522
<GROSS-OPERATING-REVENUE>                    5,508,864
<INCOME-TAX-EXPENSE>                           289,271<F6>
<OTHER-OPERATING-EXPENSES>                   4,411,963
<TOTAL-OPERATING-EXPENSES>                   4,705,326
<OPERATING-INCOME-LOSS>                        803,538
<OTHER-INCOME-NET>                            (70,358)<F6><F7>
<INCOME-BEFORE-INTEREST-EXPEN>                 737,272
<TOTAL-INTEREST-EXPENSE>                       377,561
<NET-INCOME>                                   359,711
<PREFERRED-STOCK-DIVIDENDS>                          0<F7>
<EARNINGS-AVAILABLE-FOR-COMM>                  359,711
<COMMON-STOCK-DIVIDENDS>                       259,615
<TOTAL-INTEREST-ON-BONDS>                            0<F8>
<CASH-FLOW-OPERATIONS>                       1,570,702
<EPS-PRIMARY>                                     1.66
<EPS-DILUTED>                                        0
<FN>

<F1> This item is not disclosed as a separate line item on the Consolidated
     Balance Sheet.

<F2> Includes a deduction of $3,358 thousand for preference stock expense of
     ComEd.

<F3> Preferred and Preference Stocks of ComEd.

<F4> $996,197 thousand of notes and long-term notes payable to banks is included
     in LONG-TERM-DEBT-NET.

<F5> Includes $350,000 thousand of ComEd-obligated mandatorily redeemable 
     preferred securities of subsidiary trusts.

<F6> A tax benefit of $4,092 thousand related to nonoperating activities is 
     included in INCOME-TAX-EXPENSE.

<F7> A $45,914 thousand provision for preferred and preference stock dividends
     of ComEd and $21,433 thousand provision for preferred securities dividends 
     of subsidiary trusts are included in OTHER-INCOME-NET.

<F8> This item is not disclosed as a separate line item on the Statement of
     Consolidated Income.
</FN>
        

</TABLE>