Exhibit 32.1

                              CERTIFICATION OF THE
                      CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                             PURSUANT TO SECTION 906
                        OF THE SARBANES-OXLEY ACT OF 2002

     In  connection  with the Report on Form 10-Q for the period ended March 31,
2007 of KeySpan  Corporation (the  "Corporation"),  as filed with the Securities
and Exchange Commission on the date hereof (the "Report"),  I, Robert B. Catell,
Chairman and Chief Executive Officer of the Corporation, certify, pursuant to 18
U.S.C.  Section 1350, as adopted  pursuant to Section 906 of the  Sarbanes-Oxley
Act of 2002, that:

     (1)  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)  The  information  contained  in the  Report  fairly  presents,  in all
          material respects,  the financial  condition and results of operations
          of the Corporation.


Date: April 27, 2007


                                             /s/ Robert B. Catell
                                             --------------------
                                             Robert B. Catell
                                             Chairman of the Board of Directors
                                             and Chief Executive Officer