EXHIBIT 99(b)

                                 TXU GAS COMPANY

                       Certificate Pursuant to Section 906
                         of Sarbanes - Oxley Act of 2002

     The undersigned, Earl Nye, Chairman of the Board and Chief Executive of TXU
Gas Company (the "Company"), DOES HEREBY CERTIFY that:

     1.   The Company's Quarterly Report on Form 10-Q for the quarter ended June
          30, 2002 (the "Report") fully complies with the requirements of
          section 13(a) or 15(d) of the Securities Exchange Act of 1934, as
          amended; and

     2.   Information contained in the Report fairly presents, in all material
          respects, the financial condition and results of operation of the
          Company.

     IN WITNESS WHEREOF, the undersigned has caused this instrument to be
executed this 14th day of August, 2002.

                                                        /s/ Erle Nye
                                                --------------------------------
                                                Name:  Erle Nye
                                                Title: Chairman of the Board and
                                                       Chief Executive