As filed with the Securities and Exchange Commission on July 25, 2003 Registration No. 333-61196 SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 ---------------------------------------- POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-3 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ---------------------------------------- Ionics, Incorporated (Exact name of Registrant as specified in its charter) ----------------------------- Massachusetts 04-2068530 (State or other jurisdiction (I.R.S. Employer of incorporation or organization) Identification Number) 65 Grove Street Watertown, MA 02472-2882 (617) 926-2510 (Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices) ---------------------------------------- Douglas R. Brown President and Chief Executive Officer Ionics, Incorporated 65 Grove Street Watertown, MA 02472-2882 (617) 926-2500 (Name, address, including zip code, and telephone number, including area code, of agent for service) ---------------------------------------- Copies of all communications, including all communications sent to the agent for service, should be sent to: Stephen Korn, Esq. Mark H. Burnett, Esq. Vice President and General Counsel Testa, Hurwitz & Thibeault, LLP Ionics, Incorporated Oliver Street Tower 65 Grove Street 125 High Street Watertown, MA 02472-2882 Boston, Massachusetts 02110 (617) 926-2510 (617) 248-7000 Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective. ---------------------------------------- The Registrant hereby removes from registration under this Registration Statement (333-61196) the 574,800 shares of Common Stock, $1.00 par value per share, registered hereunder (all shares originally registered hereunder being referred to as the "Offered Shares") that have not been sold pursuant to this Registration Statement. By the terms of this Registration Statement and an agreement by and among the Registrant and certain holders of Offered Shares, the Registrant was required to keep this Registration Statement effective until the earliest of (i) the date on which all of the Offered Shares have been sold, (ii) the date on which all of the Offered Shares are able to be sold in a single transaction under Rule 144 of the Securities Act of 1933 or (iii) April 18, 2003. A total of 300,200 Offered Shares have been sold or otherwise transferred by selling stockholders under this Registration Statement. Pursuant to the Registrant's Undertaking in Item 17 of this Registration Statement, the Registrant hereby removes from registration the 574,800 Offered Shares that have not been sold pursuant to this Registration Statement prior to the date hereof. Signatures Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Post-Effective Amendment No.1 to this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Watertown and Commonwealth of Massachusetts on the 25th day of July, 2003. IONICS, INCORPORATED By: /s/ Douglas R. Brown ----------------------- Douglas R. Brown, President and Chief Executive Officer Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 1 to this Registration Statement has been signed by the following persons in the capacities and on the dates indicated. Signature Title Date President, Chief Executive Officer and Director /s/ Douglas R. Brown (Principal Executive Officer) July 25, 2003 --------------------------- Douglas R. Brown Vice President and Chief Financial Officer /s/ Daniel M. Kuzmak (Principal Financial Officer) July 25, 2003 --------------------------- Daniel M. Kuzmak Vice President and Corporate Controller /s/ Anthony Di Paola (Principal Accounting Officer) July 25, 2003 --------------------------- Anthony Di Paola /s/ * Director July 25, 2003 --------------------------- Stephen L. Brown Chairman of the Board and /s/ * Director July 25, 2003 --------------------------- Arthur L. Goldstein /s/ * Director July 25, 2003 --------------------------- Kathleen F. Feldstein /s/ * Director July 25, 2003 --------------------------- William K. Reilly /s/ * Director July 25, 2003 --------------------------- John J. Shields /s/ * Director July 25, 2003 --------------------------- Daniel I. C. Wang /s/ * Director July 25, 2003 --------------------------- Mark S. Wrighton /s/ * Director July 25, 2003 --------------------------- Allen S. Wyett *By: /s/ Stephen Korn --------------------- Stephen Korn Attorney-in-Fact