SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

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


                                    FORM 8-K


                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934



                                 Date of Report
                       (Date of earliest event reported):

                                  June 3, 1998

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                                 THERMEDICS INC.
             (Exact name of Registrant as specified in its charter)


Massachusetts               1-9567                            04-2788806
(State or other         (Commission                        (I.R.S. Employer
jurisdiction of         File Number)                     Identification Number) 
incorporation or
organization)


470 Wildwood Street
Woburn, Massachusetts                                                     01888
(Address of principal executive offices)                             (Zip Code)


                                 (781) 938-3786
                         (Registrant's telephone number
                              including area code)












Item 5.  Other Events

         On June  3,  1998,  Thermedics  Inc.  (the  "Company")  issued  a press
release,  attached  hereto as  Exhibit  99, to  announce  its plan to conduct an
exchange offer with the existing holders of its Non-Interest-Bearing Convertible
Subordinated Debentures due 2003, pursuant to which such holders would receive a
new convertible subordinated debenture containing different terms.

Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits

         (a)      Financial Statements of Business Acquired: not applicable.

         (b)      Pro Forma Financial Information: not applicable.

         (c)      Exhibits

                  99   Press Release of the Company, dated June 3,
                       1998




                                    SIGNATURE



         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned, thereunto duly authorized, on this 3rd day of June, 1998.



                                                      THERMEDICS INC.


                                                      By: /s/ Jane E. Kirk
                                                          Jane E. Kirk
                                                          Assistant Clerk









EXHIBIT 99

                 THERMEDICS PLANS TO CONDUCT EXCHANGE OFFER WITH
  EXISTING HOLDERS OF NON-INTEREST-BEARING CONVERTIBLE SUBORDINATED DEBENTURES

         WOBURN,  Mass.,  June 3, 1998 -- Thermedics  Inc.  (ASE-TMD)  announced
today that it plans to conduct an exchange  offer with the  existing  holders of
its non-interest-bearing  convertible subordinated debentures due 2003, pursuant
to which such  holders  will receive a new  convertible  subordinated  debenture
bearing  interest  at the rate of 2 7/8  percent  per year.  In  addition to new
semiannual  interest  payments,  the new debentures will convert at a 15 percent
premium over the average  price of the common stock for a 10-day period prior to
the closing.

         For every  $1,000  principal  amount of old  debentures  submitted  for
exchange,  holders  will  receive  approximately  $730  principal  amount of new
debentures. Accordingly, at the maturity date of the new debentures, holders who
elect to exchange  their old  debentures  will receive less in principal  amount
than  they  would  have had such  holders  retained  their old  debentures.  The
maturity  date for the new  debentures  will be June 1, 2003,  the same maturity
date as the existing non-interest-bearing debentures.

         The  debentures  to be  issued  in  the  exchange  offer  will  not  be
registered under the Securities Act and may not be offered or sold in the United
States  absent  registration  or  an  applicable   exemption  from  registration
requirements.