content: 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):
  
                                  January 31, 2000
  
                      ----------------------------------------
  
  
                                   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, P.O. Box 2999
  Woburn, Massachusetts                                                      01888
  (Address of principal executive offices)                              (Zip Code)
  
  
                                   (781) 622-1000
                           (Registrant's telephone number
                                including area code)
  
  
  
  <PAGE>
  
  
  
  
  
  This Form 8-K contains forward-looking statements that involve a number of risks
  and uncertainties. Important factors that could cause actual results to differ
  materially from those indicated by such forward-looking statements are set forth
  under the heading "Forward-looking Statements" in Exhibit 13 to Thermedics
  Inc.'s Annual Report on Form 10-K for the year ended January 2, 1999. These
  include risks and uncertainties relating to: government regulation and industry
  standards, competition and technological change, intellectual property rights,
  reimbursement by insurers for medical procedures, medical community acceptance
  of medical devices, availability of materials and components, product liability,
  international operations, the Registrants' spinout and acquisition strategies,
  and the potential impact of the year 2000 on processing date-sensitive
  information.
  
  Item 5.  Other Events
           -------------
  
           On January 31, 2000, the Registrant issued a press release, attached
  hereto as Exhibit 99, regarding certain corporate transactions affecting it and
  its majority-owned public subsidiaries.
  
  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 dated January 31, 2000.
  
  
  <PAGE>
  
  
  
                                      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 31st day of January, 2000.
  
  
  
                                               THERMEDICS INC.
  
  
                                               By:  /s/ Theo Melas-Kyriazi
                                                    -----------------------------
                                                    Theo Melas-Kyriazi
                                                    Chief Financial Officer
  
  
  <PAGE>
                                                                        Exhibit 99
  Investor Contact: 781-622-1111
  Media Contact: 781-622-1252
  
                   THERMEDICS TO TAKE PUBLIC SUBSIDIARIES PRIVATE;
                 ANNOUNCES THERMO ELECTRON'S PROPOSED EXCHANGE OFFER
  
  WOBURN, Mass., January 31, 2000 - Thermedics Inc. (ASE-TMD) announced today that
  it plans to take private its Thermedics Detection Inc. and Thermo Sentron Inc.
  subsidiaries. Thermedics also announced that its parent company, Thermo Electron
  Corporation (NYSE-TMO), proposes to take it private. In addition, the company
  announced that it will seek a buyer for its Thermo Cardiosystems Inc.
  subsidiary. These actions are part of a major reorganization plan under which
  Thermo Electron will spin in, spin off, and sell various businesses to focus
  solely on its core measurement and detection instruments business.
  
           Thermedics will make cash tender offers of $8.00 per share for
  Thermedics Detection, and $15.50 per share for Thermo Sentron, in order to bring
  its own equity ownership in each of these companies to at least 90 percent. If
  successful, each of these companies would then be spun into Thermedics through a
  "short-form" merger at the same cash prices as the tender offers.
  
           Thermedics currently owns approximately 83.6 percent and 74.2 percent
  of Thermedics Detection and Thermo Sentron, respectively. Thermo Electron, which
  currently owns approximately 5.3 percent and 12.4 percent of Thermedics
  Detection and Thermo Sentron, respectively, will tender its shares to Thermedics
  in these tender offers.
  
           Following these tender offers, Thermedics, in turn, would be taken
  private. Thermo Electron has announced that it will conduct an exchange offer
  for any and all of the outstanding shares of Thermedics common stock held by
  minority shareholders. In the exchange offer, holders of Thermedics common stock
  will receive shares of Thermo Electron common stock in exchange for their
  Thermedics shares. Thermo Electron expects to announce the exchange ratio for
  this transaction shortly after Thermedics conducts the tender offers for
  Thermedics Detection and Thermo Sentron.
  
           Thermo Electron, which currently owns approximately 75.7 percent of the
  outstanding shares of Thermedics common stock, will condition the exchange offer
  on receiving acceptances from holders of enough shares so that, when combined
  with its current share ownership, Thermo Electron's ownership reaches at least
  90 percent. If Thermo Electron achieves this 90-percent-ownership threshold, it
  will acquire all remaining outstanding shares of Thermedics through a short-form
  merger. In the short-form merger, minority shareholders who do not participate
  in the exchange offer would also receive shares of Thermo Electron common stock
  in exchange for their Thermedics common stock at the same ratio.
  
           The tender offers and exchange offer will require Securities and
  Exchange Commission clearance of necessary filings; the exchange offer will
  require establishment of the exchange ratio. The short-form merger would not
  require Thermedics board or shareholder approval.
  
           Thermedics plans to conduct its subsidiary tender offers during the
  second quarter of 2000. If Thermedics successfully obtains ownership of at least
  90 percent of the outstanding Thermo Sentron and Thermedics Detection shares, it
  expects to complete these spin-ins by the end of the second quarter of 2000.
  Thermo Electron plans to conduct the exchange offer for Thermedics common stock
  during the
  
                                       -more-
  
  
  <PAGE>
  
  
  
  
  third quarter of 2000. If Thermo Electron successfully obtains ownership of at
  least 90 percent of the outstanding Thermedics shares, it expects to complete
  the spin-in of Thermedics by the end of the third quarter of 2000.
  
           Obligations under Thermedics' 2.88% convertible subordinated debentures
  due June 1, 2003, and its 0% convertible subordinated debentures due June 1,
  2003, would be assumed by Thermo Electron in the short-form merger, and the
  debentures would be convertible into Thermo Electron common stock.
  
           Upon completion of the proposed Thermedics spin-in, Thermedics' medical
  equipment businesses, excluding Thermo Cardiosystems, would be contributed to a
  new medical products company, which, in turn, would be spun off from Thermo
  Electron as a dividend to Thermo Electron shareholders. Thermedics Detection and
  Thermo Sentron will remain businesses of the new focused Thermo Electron
  measurement and detection instruments company.
  
  SALE OF THERMO CARDIOSYSTEMS
  Thermedics has also announced that it will seek a buyer for Thermo
  Cardiosystems. Thermo Electron and Thermedics have concluded that Thermo
  Cardiosystems would better prosper as part of another organization providing
  greater focus, resources, and targeted marketing strength.
  
           Thermedics Inc. develops, manufactures, and markets diverse product
  lines, including implantable heart-assist devices and other biomedical products,
  security instruments, and equipment that assures the quality of a wide variety
  of consumer products and bulk materials. Thermedics is a public subsidiary of
  Thermo Electron Corporation. More information is available on the Internet at
  http://www.thermo.com/subsid/tmd1.html.
  
  OTHER IMPORTANT INFORMATION:
  THE TENDER OFFERS DESCRIBED IN THIS ANNOUNCEMENT FOR THE OUTSTANDING SHARES OF
  THERMEDICS DETECTION AND THERMO SENTRON COMMON STOCK HAVE NOT YET COMMENCED. AS
  SOON AS THE TENDER OFFERS COMMENCE, WE WILL FILE TENDER OFFER STATEMENTS WITH
  THE SECURITIES AND EXCHANGE COMMISSION. YOU SHOULD READ THE TENDER OFFER
  STATEMENTS WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT
  INFORMATION ABOUT THE TENDER OFFERS. YOU CAN OBTAIN THE TENDER OFFER STATEMENTS
  AND OTHER DOCUMENTS THAT ARE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION
  FOR FREE ON THE SECURITIES AND EXCHANGE COMMISSION'S WEB SITE AT
  http://www.sec.gov. IF YOU WRITE US OR CALL US, WE WILL SEND YOU THESE DOCUMENTS
  FOR FREE WHEN THEY ARE AVAILABLE:
  
           * TENDER OFFER STATEMENTS (EXCEPT FOR EXHIBITS)
           * OFFERS TO PURCHASE
           * LETTERS OF TRANSMITTAL
           * NOTICES OF GUARANTEED DELIVERY
  
  YOU CAN CALL US AT (781) 622-1111 OR WRITE TO US AT:
  
           INVESTOR RELATIONS DEPARTMENT
           THERMEDICS INC.
           81 WYMAN STREET, P.O. BOX 9046
           WALTHAM, MA 02454-9046
  
                                       -more-
  
  
  <PAGE>
  
  
  
  
  THE EXCHANGE OFFER BY THERMO ELECTRON FOR OUR COMMON STOCK THAT IS DESCRIBED IN
  THIS ANNOUNCEMENT HAS NOT YET COMMENCED. ONCE THE EXCHANGE OFFER COMMENCES, WE
  WILL FILE A SOLICITATION/RECOMMENDATION STATEMENT WITH THE SECURITIES AND
  EXCHANGE COMMISSION. YOU SHOULD READ THIS DOCUMENT WHEN IT BECOMES AVAILABLE
  BECAUSE IT WILL CONTAIN IMPORTANT INFORMATION ABOUT THE EXCHANGE OFFER. YOU CAN
  OBTAIN THE SOLICITATION/RECOMMENDATION STATEMENT AND OTHER DOCUMENTS THAT WILL
  BE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION FOR FREE WHEN THEY ARE
  AVAILABLE ON THE SECURITIES AND EXCHANGE COMMISSION'S WEB SITE AT
  http://www.sec.gov. ALSO, IF YOU WRITE US OR CALL US AT THE ABOVE ADDRESS AND
  PHONE NUMBER, WE WILL SEND YOU THE SOLICITATION/RECOMMENDATION STATEMENT FOR
  FREE WHEN IT IS AVAILABLE.
  
  The following constitutes a "Safe Harbor" statement under the Private Securities
  Litigation Reform Act of 1995: This press release contains forward-looking
  statements that involve a number of risks and uncertainties. Important factors
  that could cause actual results to differ materially from those indicated by
  such forward-looking statements are set forth under the heading "Forward-looking
  Statements" in Exhibit 13 to the company's annual report on Form 10-K for the
  year ended January 2, 1999. These include risks and uncertainties relating to:
  government regulation and industry standards, competition and technological
  change, intellectual property rights, reimbursement by insurers for medical
  procedures, medical community acceptance of medical devices, availability of
  materials and components, product liability, international operations, the
  company's spinout and acquisition strategies, and the potential impact of the
  year 2000 on processing date-sensitive information.
  
  
                                        # # #
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text: 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):
  
                                  January 31, 2000
  
                      ----------------------------------------
  
                                   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, P.O. Box 2999
  Woburn, Massachusetts                                                      01888
  (Address of principal executive offices)                              (Zip Code)
  
                                   (781) 622-1000
                           (Registrant's telephone number
                                including area code)
  This Form 8-K contains forward-looking statements that involve a number of risks
  and uncertainties. Important factors that could cause actual results to differ
  materially from those indicated by such forward-looking statements are set forth
  under the heading "Forward-looking Statements" in Exhibit 13 to Thermedics
  Inc.'s Annual Report on Form 10-K for the year ended January 2, 1999. These
  include risks and uncertainties relating to: government regulation and industry
  standards, competition and technological change, intellectual property rights,
  reimbursement by insurers for medical procedures, medical community acceptance
  of medical devices, availability of materials and components, product liability,
  international operations, the Registrants' spinout and acquisition strategies,
  and the potential impact of the year 2000 on processing date-sensitive
  information.
  
  Item 5.  Other Events
           -------------
  
           On January 31, 2000, the Registrant issued a press release, attached
  hereto as Exhibit 99, regarding certain corporate transactions affecting it and
  its majority-owned public subsidiaries.
  
  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 dated January 31, 2000.
  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 31st day of January, 2000.
  
                                               THERMEDICS INC.
  
                                               By:  /s/ Theo Melas-Kyriazi
                                                    -----------------------------
                                                    Theo Melas-Kyriazi
                                                    Chief Financial Officer
  Exhibit 99
  Investor Contact: 781-622-1111
  Media Contact: 781-622-1252
  
                   THERMEDICS TO TAKE PUBLIC SUBSIDIARIES PRIVATE;
                 ANNOUNCES THERMO ELECTRON'S PROPOSED EXCHANGE OFFER
  
  WOBURN, Mass., January 31, 2000 - Thermedics Inc. (ASE-TMD) announced today that
  it plans to take private its Thermedics Detection Inc. and Thermo Sentron Inc.
  subsidiaries. Thermedics also announced that its parent company, Thermo Electron
  Corporation (NYSE-TMO), proposes to take it private. In addition, the company
  announced that it will seek a buyer for its Thermo Cardiosystems Inc.
  subsidiary. These actions are part of a major reorganization plan under which
  Thermo Electron will spin in, spin off, and sell various businesses to focus
  solely on its core measurement and detection instruments business.
  
           Thermedics will make cash tender offers of $8.00 per share for
  Thermedics Detection, and $15.50 per share for Thermo Sentron, in order to bring
  its own equity ownership in each of these companies to at least 90 percent. If
  successful, each of these companies would then be spun into Thermedics through a
  "short-form" merger at the same cash prices as the tender offers.
  
           Thermedics currently owns approximately 83.6 percent and 74.2 percent
  of Thermedics Detection and Thermo Sentron, respectively. Thermo Electron, which
  currently owns approximately 5.3 percent and 12.4 percent of Thermedics
  Detection and Thermo Sentron, respectively, will tender its shares to Thermedics
  in these tender offers.
  
           Following these tender offers, Thermedics, in turn, would be taken
  private. Thermo Electron has announced that it will conduct an exchange offer
  for any and all of the outstanding shares of Thermedics common stock held by
  minority shareholders. In the exchange offer, holders of Thermedics common stock
  will receive shares of Thermo Electron common stock in exchange for their
  Thermedics shares. Thermo Electron expects to announce the exchange ratio for
  this transaction shortly after Thermedics conducts the tender offers for
  Thermedics Detection and Thermo Sentron.
  
           Thermo Electron, which currently owns approximately 75.7 percent of the
  outstanding shares of Thermedics common stock, will condition the exchange offer
  on receiving acceptances from holders of enough shares so that, when combined
  with its current share ownership, Thermo Electron's ownership reaches at least
  90 percent. If Thermo Electron achieves this 90-percent-ownership threshold, it
  will acquire all remaining outstanding shares of Thermedics through a short-form
  merger. In the short-form merger, minority shareholders who do not participate
  in the exchange offer would also receive shares of Thermo Electron common stock
  in exchange for their Thermedics common stock at the same ratio.
  
           The tender offers and exchange offer will require Securities and
  Exchange Commission clearance of necessary filings; the exchange offer will
  require establishment of the exchange ratio. The short-form merger would not
  require Thermedics board or shareholder approval.
  
           Thermedics plans to conduct its subsidiary tender offers during the
  second quarter of 2000. If Thermedics successfully obtains ownership of at least
  90 percent of the outstanding Thermo Sentron and Thermedics Detection shares, it
  expects to complete these spin-ins by the end of the second quarter of 2000.
  Thermo Electron plans to conduct the exchange offer for Thermedics common stock
  during the
  
                                       -more-
  third quarter of 2000. If Thermo Electron successfully obtains ownership of at
  least 90 percent of the outstanding Thermedics shares, it expects to complete
  the spin-in of Thermedics by the end of the third quarter of 2000.
  
           Obligations under Thermedics' 2.88% convertible subordinated debentures
  due June 1, 2003, and its 0% convertible subordinated debentures due June 1,
  2003, would be assumed by Thermo Electron in the short-form merger, and the
  debentures would be convertible into Thermo Electron common stock.
  
           Upon completion of the proposed Thermedics spin-in, Thermedics' medical
  equipment businesses, excluding Thermo Cardiosystems, would be contributed to a
  new medical products company, which, in turn, would be spun off from Thermo
  Electron as a dividend to Thermo Electron shareholders. Thermedics Detection and
  Thermo Sentron will remain businesses of the new focused Thermo Electron
  measurement and detection instruments company.
  
  SALE OF THERMO CARDIOSYSTEMS
  Thermedics has also announced that it will seek a buyer for Thermo
  Cardiosystems. Thermo Electron and Thermedics have concluded that Thermo
  Cardiosystems would better prosper as part of another organization providing
  greater focus, resources, and targeted marketing strength.
  
           Thermedics Inc. develops, manufactures, and markets diverse product
  lines, including implantable heart-assist devices and other biomedical products,
  security instruments, and equipment that assures the quality of a wide variety
  of consumer products and bulk materials. Thermedics is a public subsidiary of
  Thermo Electron Corporation. More information is available on the Internet at
  http://www.thermo.com/subsid/tmd1.html.
  
  OTHER IMPORTANT INFORMATION:
  THE TENDER OFFERS DESCRIBED IN THIS ANNOUNCEMENT FOR THE OUTSTANDING SHARES OF
  THERMEDICS DETECTION AND THERMO SENTRON COMMON STOCK HAVE NOT YET COMMENCED. AS
  SOON AS THE TENDER OFFERS COMMENCE, WE WILL FILE TENDER OFFER STATEMENTS WITH
  THE SECURITIES AND EXCHANGE COMMISSION. YOU SHOULD READ THE TENDER OFFER
  STATEMENTS WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT
  INFORMATION ABOUT THE TENDER OFFERS. YOU CAN OBTAIN THE TENDER OFFER STATEMENTS
  AND OTHER DOCUMENTS THAT ARE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION
  FOR FREE ON THE SECURITIES AND EXCHANGE COMMISSION'S WEB SITE AT
  http://www.sec.gov. IF YOU WRITE US OR CALL US, WE WILL SEND YOU THESE DOCUMENTS
  FOR FREE WHEN THEY ARE AVAILABLE:
  
           * TENDER OFFER STATEMENTS (EXCEPT FOR EXHIBITS)
           * OFFERS TO PURCHASE
           * LETTERS OF TRANSMITTAL
           * NOTICES OF GUARANTEED DELIVERY
  
  YOU CAN CALL US AT (781) 622-1111 OR WRITE TO US AT:
  
           INVESTOR RELATIONS DEPARTMENT
           THERMEDICS INC.
           81 WYMAN STREET, P.O. BOX 9046
           WALTHAM, MA 02454-9046
  
                                       -more-
  THE EXCHANGE OFFER BY THERMO ELECTRON FOR OUR COMMON STOCK THAT IS DESCRIBED IN
  THIS ANNOUNCEMENT HAS NOT YET COMMENCED. ONCE THE EXCHANGE OFFER COMMENCES, WE
  WILL FILE A SOLICITATION/RECOMMENDATION STATEMENT WITH THE SECURITIES AND
  EXCHANGE COMMISSION. YOU SHOULD READ THIS DOCUMENT WHEN IT BECOMES AVAILABLE
  BECAUSE IT WILL CONTAIN IMPORTANT INFORMATION ABOUT THE EXCHANGE OFFER. YOU CAN
  OBTAIN THE SOLICITATION/RECOMMENDATION STATEMENT AND OTHER DOCUMENTS THAT WILL
  BE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION FOR FREE WHEN THEY ARE
  AVAILABLE ON THE SECURITIES AND EXCHANGE COMMISSION'S WEB SITE AT
  http://www.sec.gov. ALSO, IF YOU WRITE US OR CALL US AT THE ABOVE ADDRESS AND
  PHONE NUMBER, WE WILL SEND YOU THE SOLICITATION/RECOMMENDATION STATEMENT FOR
  FREE WHEN IT IS AVAILABLE.
  
  The following constitutes a "Safe Harbor" statement under the Private Securities
  Litigation Reform Act of 1995: This press release contains forward-looking
  statements that involve a number of risks and uncertainties. Important factors
  that could cause actual results to differ materially from those indicated by
  such forward-looking statements are set forth under the heading "Forward-looking
  Statements" in Exhibit 13 to the company's annual report on Form 10-K for the
  year ended January 2, 1999. These include risks and uncertainties relating to:
  government regulation and industry standards, competition and technological
  change, intellectual property rights, reimbursement by insurers for medical
  procedures, medical community acceptance of medical devices, availability of
  materials and components, product liability, international operations, the
  company's spinout and acquisition strategies, and the potential impact of the
  year 2000 on processing date-sensitive information.
  
                                        # # #