<PAGE>
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM T-1
                                    --------

                            STATEMENT OF ELIGIBILITY
                     UNDER THE TRUST INDENTURE ACT OF 1939
                 OF A CORPORATION DESIGNATED TO ACT AS TRUSTEE

                CHECK IF AN APPLICATION TO DETERMINE ELIGIBILITY
                OF A TRUSTEE PURSUANT TO SECTION 305(B)(2) _____

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

                       THE FIRST NATIONAL BANK OF CHICAGO
              (EXACT NAME OF TRUSTEE AS SPECIFIED IN ITS CHARTER)

     A NATIONAL BANKING ASSOCIATION                36-0899825
                                              (I.R.S. EMPLOYER
                                              IDENTIFICATION NUMBER)

     ONE FIRST NATIONAL PLAZA, CHICAGO, ILLINOIS        60670-0126
     (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)           (ZIP CODE)

                       THE FIRST NATIONAL BANK OF CHICAGO
                      ONE FIRST NATIONAL PLAZA, SUITE 0286
                         CHICAGO, ILLINOIS   60670-0286
            ATTN:  LYNN A. GOLDSTEIN, LAW DEPARTMENT (312) 732-6919
           (NAME, ADDRESS AND TELEPHONE NUMBER OF AGENT FOR SERVICE)

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

                        HOUSTON INDUSTRIES INCORPORATED
              (EXACT NAME OF OBLIGOR AS SPECIFIED IN ITS CHARTER)

                TEXAS                                           74-1885573
     (STATE OR OTHER JURISDICTION OF                         (I.R.S. EMPLOYER
     INCORPORATION OR ORGANIZATION)                     IDENTIFICATION NUMBER)


             1111 LOUISIANA
             HOUSTON, TEXAS                                77002
     (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)           (ZIP CODE)


                                DEBT SECURITIES
                        (TITLE OF INDENTURE SECURITIES)
<PAGE>
 
ITEM 1.   GENERAL INFORMATION.  FURNISH THE FOLLOWING
          INFORMATION AS TO THE TRUSTEE:

          (A) NAME AND ADDRESS OF EACH EXAMINING OR
          SUPERVISING AUTHORITY TO WHICH IT IS SUBJECT.

          Comptroller of Currency, Washington, D.C.,
          Federal Deposit Insurance Corporation,
          Washington, D.C., The Board of Governors of
          the Federal Reserve System, Washington D.C.

          (B) WHETHER IT IS AUTHORIZED TO EXERCISE
          CORPORATE TRUST POWERS.

          The trustee is authorized to exercise corporate
          trust powers.

ITEM 2.   AFFILIATIONS WITH THE OBLIGOR.  IF THE OBLIGOR
          IS AN AFFILIATE OF THE TRUSTEE, DESCRIBE EACH
          SUCH AFFILIATION.

          No such affiliation exists with the trustee.

 
ITEM 16.  LIST OF EXHIBITS.   LIST BELOW ALL EXHIBITS FILED AS A
          PART OF THIS STATEMENT OF ELIGIBILITY.

          1.  A copy of the articles of association of the
              trustee now in effect.*
 
          2.  A copy of the certificates of authority of the
              trustee to commence business.*

          3.  A copy of the authorization of the trustee to
              exercise corporate trust powers.*

          4.  A copy of the existing by-laws of the trustee.*

          5.  Not Applicable.

          6.  The consent of the trustee required by
              Section 321(b) of the Act.

          7. A copy of the latest report of condition of the
             trustee published pursuant to law or the
             requirements of its supervising or examining
             authority.

                                       2
<PAGE>
 
          8.  Not Applicable.

          9.  Not Applicable.


     Pursuant to the requirements of the Trust Indenture Act of 1939, as
amended, the trustee, The First National Bank of Chicago, a national banking
association organized and existing under the laws of the United States of
America, has duly caused this Statement of Eligibility to be signed on its
behalf by the undersigned, thereunto duly authorized, all in the City of Chicago
and the State of Illinois, on this 26th day of June, 1997.


            THE FIRST NATIONAL BANK OF CHICAGO,
            TRUSTEE

            By  /s/ John R. Prendiville
                --------------------------------
               John R. Prendiville
               Vice President

 


* EXHIBIT 1, 2, 3 AND 4 ARE HEREIN INCORPORATED BY REFERENCE TO EXHIBITS BEARING
IDENTICAL NUMBERS IN ITEM 16 OF THE FORM T-1 OF THE FIRST NATIONAL BANK OF
CHICAGO, FILED AS EXHIBIT 25.1 TO THE REGISTRATION STATEMENT ON FORM S-3 OF
SUNAMERICA, INC., FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON OCTOBER
25, 1996 (REGISTRATION NO. 333-14201).

                                       3
<PAGE>
 
                                   EXHIBIT 6


                      THE CONSENT OF THE TRUSTEE REQUIRED
                          BY SECTION 321(b) OF THE ACT


 
                                                 June 26, 1997


Securities and Exchange Commission
Washington, D.C.  20549

Gentlemen:

     In connection with the qualification of an indenture between Houston
Industries Incorporated and The First National Bank of Chicago, the undersigned,
in accordance with Section 321(b) of the Trust Indenture Act of 1939, as
amended, hereby consents that the reports of examinations of the undersigned,
made by Federal or State authorities authorized to make such examinations, may
be furnished by such authorities to the Securities and Exchange Commission upon
its request therefor.


                                 Very truly yours,

                                 THE FIRST NATIONAL BANK OF CHICAGO
 
                                 By   /s/ John R. Prendiville
                                      ---------------------------------  
                                      John R. Prendiville
                                      Vice President

                                       4
<PAGE>
 
                                   EXHIBIT 7
<TABLE>
<CAPTION>
 
Legal Title of Bank:              The First National Bank of Chicago            Call Date: 03/31/97  ST-BK:  17-1630 FFIEC 031
Address:                          One First National Plaza, Ste 0303                                                 Page RC-1
City, State  Zip:                 Chicago, IL  60670
FDIC Certificate No.:   0/3/6/1/8
                        ---------

CONSOLIDATED REPORT OF CONDITION FOR INSURED COMMERCIAL
AND STATE-CHARTERED SAVINGS BANKS FOR MARCH 31, 1997

All schedules are to be reported in thousands of dollars.  Unless otherwise indicated, report the amount
outstanding of the last business day of the quarter.

SCHEDULE RC--BALANCE SHEET

                                                                                                             C400   
                                                                         DOLLAR AMOUNTS IN                   ----
                                                                             THOUSANDS          RCFD      BIL MIL THOU
                                                                         ------------------     ----      ------------
<S>                                                                      <C>                    <C>        <C>               <C>    

ASSETS
1.  Cash and balances due from depository institutions (from Schedule
    RC-A):
    a. Noninterest-bearing balances and currency and coin(1).............                         0081        3,871,170       1.a.
    b. Interest-bearing balances(2)......................................                         0071        6,498,314       1.b.
2.  Securities
    a. Held-to-maturity securities(from Schedule RC-B, column A).........                         1754                0       2.a.
    b. Available-for-sale securities (from Schedule RC-B, column D)......                         1773        3,901,208       2.b.
3.  Federal funds sold and securities purchased under agreements to
    resell...............................................................                         1350        4,612,975       3.
4.  Loans and lease financing receivables:
    a. Loans and leases, net of unearned income (from Schedule
    RC-C)................................................................  RCFD 2122 23,345,201                               4.a.
    b. LESS: Allowance for loan and lease losses.........................  RCFD 3123    420,963                               4.b.
    c. LESS: Allocated transfer risk reserve.............................  RCFD 3128          0                               4.c.
    d. Loans and leases, net of unearned income, allowance, and
       reserve (item 4.a minus 4.b and 4.c)..............................                         2125       22,924,238       4.d.
5.  Trading assets (from Schedule RD-D)..................................                         3545        8,792,158       5.
6.  Premises and fixed assets (including capitalized leases).............                         2145          706,928       6.
7.  Other real estate owned (from Schedule RC-M).........................                         2150            6,563       7.
8.  Investments in unconsolidated subsidiaries and associated
    companies (from Schedule RC-M).......................................                         2130           61,551       8.
9.  Customers' liability to this bank on acceptances outstanding.........                         2155          488,866       9.
10. Intangible assets (from Schedule RC-M)...............................                         2143          291,569       10.
11. Other assets (from Schedule RC-F)....................................                         2160        1,775,283       11.
12. Total assets (sum of items 1 through 11).............................                         2170       53,930,823       12.
 
------------------
</TABLE>

(1)  Includes cash items in process of collection and unposted debits.
(2)  Includes time certificates of deposit not held for trading.
 
 

                                       5
<PAGE>
 
<TABLE>
<CAPTION>
 
Legal Title of Bank:                      The First National Bank of Chicago       Call Date:  03/31/97 ST-BK:  17-1630 FFIEC 031
Address:                                  One First National Plaza, Ste 0303                                              Page RC-2
City, State  Zip:                         Chicago, IL  60670
FDIC Certificate No.:                     0/3/6/1/8
                                          ---------
 
SCHEDULE RC-CONTINUED
                                                                           DOLLAR AMOUNTS IN
                                                                               Thousands                  BIL MIL THOU
                                                                           -----------------              ------------
LIABILITIES
<S>                                                                     <C>                   <C>          <C>              <C> 
13.  Deposits:
     a. In domestic offices (sum of totals of columns A and C
        from Schedule RC-E, part 1).................................                           RCON 2200    21,550,056      13.a.
        (1) Noninterest-bearing(1)..................................    RCON 6631  8,895,137                                13.a.1
        (2) Interest-bearing........................................    RCON 6636 12,654,919                                13.a.2
     b. In foreign offices, Edge and Agreement subsidiaries, and
        IBFs (from Schedule RC-E, part II)..........................                          RCFN 2200     12,364,650      13.b.
        (1) Noninterest bearing.....................................    RCFN 6631    287,496                                13.b.1
        (2) Interest-bearing........................................    RCFN 6636 12,077,154                                13.b.2
14.  Federal funds purchased and securities sold under agreements
     to repurchase:.................................................                          RCFD 2800      3.817,421      14
15.  a. Demand notes issued to the U.S. Treasury....................                          RCON 2840         63,621      15.a.
     b. Trading Liabilities (from Sechedule RC-D)...................                          RCFD 3548      5,872,831      15b.
16.  Other borrowed money:
     a. With original maturity of one year or less..................                          RCFD 2332      2,607,549      16.a.
     b. With original maturity of more than one year................                          RCFD 2333        322,414      16b.
17.  Not applicable
18.  Bank's liability on acceptance executed and outstanding........                          RCFD 2920        488,866      18.
19.  Subordinated notes and debentures..............................                          RCFD 3200      1,550,000      19.
20.  Other liabilities (from Schedule RC-G).........................                          RCFD 2930      1,196,229      20.
21.  Total liabilities (sum of items 13 through 20).................                          RCFD 2948    49 ,833,637      21.
22.  Not applicable
EQUITY CAPITAL
23.  Perpetual preferred stock and related surplus..................                          RCFD 3838              0      23.
24.  Common stock...................................................                          RCFD 3230        200,858      24.
25.  Surplus (exclude all surplus related to preferred stock).......                          RCFD 3839      2,944,244      25.
26.  a. Undivided profits and capital reserves......................                          RCFD 3632        954,885      26.a.
     b. Net unrealized holding gains (losses) on available-for-sale
        securities..................................................                          RCFD 8434         (1,089)     26.b.
27.  Cumulative foreign currency translation adjustments............                          RCFD 3284         (1,712)     27.
28.  Total equity capital (sum of items 23 through 27)..............                          RCFD 3210      4,097,186      28.
29.  Total liabilities, limited-life preferred stock, and equity
     capital (sum of items 21, 22, and 28)..........................                          RCFD 3300     53,930,823      29.

</TABLE>

<TABLE> 
<CAPTION> 

Memorandum
To be reported only with the March Report of Condition.
1. Indicate in the box at the right the number of the statement below that best describes the  most                 
   comprehensive level of auditing work performed for the bank by independent external                                Number 
                                                                                                                    ---------    
   auditors as of any date during 1996 .......................................................RCFD 6724.............   2        M.1.

<S>                                                                    <C>        
  
1 =  Independent audit of the bank conducted in accordance              4. = Directors' examination of the bank performed by other 
     with generally accepted auditing standards by a certified               external auditors (may be required by state chartering
     public accounting firm which submits a report on the bank               authority)                                         
2 =  Independent audit of the bank's parent holding company             5 =  Review of the bank's financial statements by external 
     conducted in accordance with generally accepted auditing                auditors
     standards by a certified public accounting firm which              6 =  Compilation of the bank's financial statements by 
     submits a report on the consolidated holding company                    external auditors 
     (but not on the bank separately)                                   7 =  Other audit procedures (excluding tax preparation work)
3 =  Directors' examination of the bank conducted in                    8 =  No external audit work
     accordance with generally accepted auditing standards
     by a certified public accounting firm (may be required by
     state chartering authority)

-------------------
(1) Includes total demand deposits and noninterest-bearing time and savings deposits.
</TABLE> 

                                       6