UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                     FORM 15

 CERTIFICATION AND NOTICE OF TERMINATION OF REGISTRATION UNDER SECTION 12(G) OF
        THE SECURITIES EXCHANGE ACT OF 1934 OR SUSPENSION OF DUTY TO FILE
   REPORTS UNDER SECTIONS 13 AND 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934.


                                    001-07211
                             Commission File Number


                              IONICS, INCORPORATED
             (Exact name of registrant as specified in its charter)


                                 65 GROVE STREET
                       WATERTOWN, MASSACHUSETTS 02472-2882
                            TELEPHONE: (617) 926-2500
               (Address, including zip code, and telephone number,
       including area code, of registrant's principal executive offices)


                     COMMON STOCK, PAR VALUE $1.00 PER SHARE
            (Title of each class of securities covered by this Form)


                                      NONE
             (Titles of all other classes of securities for which a
           duty to file reports under section 13(a) or 15(d) remains)


       Please place an X in the box(es) to designate the appropriate rule
provision(s) relied upon to terminate or suspend the duty to file reports:


     Rule 12g-4(a)(1)(i)   [X]          Rule 12h-3(b)(1)(i)   [X]
     Rule 12g-4(a)(1)(ii)  [ ]          Rule 12h-3(b)(1)(ii)  [ ]
     Rule 12g-4(a)(2)(i)   [ ]          Rule 12h-3(b)(2)(i)   [ ]
     Rule 12g-4(a)(2)(ii)  [ ]          Rule 12h-3(b)(2)(ii)  [ ]
                                        Rule 15d-6            [ ]


           Approximate number of holders of record as of the certification or
notice date: One (1)
             -------

           Pursuant to the requirements of the Securities Exchange Act of 1934,
IONICS, INCORPORATED has caused this certification/notice to be signed on its
behalf by the undersigned duly authorized person.


Date:  February 22, 2005              By: /s/ Douglas R. Brown
       ------------------------           --------------------------------------
                                          Name: Douglas R. Brown
                                          Title: President and Chief Executive
                                                 Officer