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):

                                  July 21, 1998

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


                             THERMOQUEST CORPORATION
             (Exact name of Registrant as specified in its charter)


Delaware                      1-14262                       77-0407461
(State or other              (Commission               (I.R.S. Employer
jurisdiction of               File Number)             Identification Number) 
incorporation or
organization)

2215 Grand Avenue Parkway
Austin, Texas                                                   78728-3812
(Address of principal executive offices)                         (Zip Code)


                                (512) 251-1400
                         (Registrant's telephone number
                              including area code)



<PAGE>








Item 5.     Other Events

      On July 21, 1998,  ThermoQuest  Corporation (the "Company") issued a press
release,  attached hereto as Exhibit 99, regarding its expected operating income
for the quarter ended July 4, 1998.

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 July 21,
                  1998






<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 22nd day of July, 1998.



                                    THERMOQUEST CORPORATION



                                    By: /s/ Sandra L. Lambert
                                          Sandra L. Lambert
                                          Secretary






<PAGE>


EXHIBIT 99

                 THERMOQUEST EXPECTS SECOND QUARTER OPERATING
                     INCOME TO BE APPROXIMATELY $15 MILLION

AUSTIN,  Texas,  July 21, 1998 -- ThermoQuest  Corporation  (ASE-TMQ)  announced
today that it expects  operating  income for the second  quarter,  ended July 4,
1998, to be approximately $15 million.  As a result,  diluted earnings per share
for the 1998 quarter will be approximately $.16, compared with $.20 for the same
period in 1997.

      "We  experienced  lower-than-expected  revenues  primarily  due to  orders
received  late in the quarter,"  said Dr.  Richard W.K.  Chapman,  president and
chief  executive  officer of  ThermoQuest.  "We ended the second  quarter with a
backlog estimated to be $7 million higher than the first quarter of 1998."

      ThermoQuest  plans to release its complete  quarterly  earnings results on
August 10, 1998.

     ThermoQuest   Corporation   develops,    manufactures,   and   sells   mass
spectrometers,   liquid   chromatographs,   and  gas   chromatographs   for  the
environmental,  pharmaceutical,  and industrial  marketplaces.  These analytical
instruments are used in the  quantitative and qualitative  chemical  analysis of
organic and inorganic compounds at ultratrace levels of detection.  In addition,
the  company   manufactures   scientific   equipment  for  the  preparation  and
preservation  of  chemical  samples,  and  consumables  for  the  chromatography
industry.  ThermoQuest is a public subsidiary of Thermo Instrument Systems Inc.,
a Thermo  Electron  company.  More  information  is available on the Internet at
http://www.thermo.com/subsid/tmq1.html.

     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 3,  1998.  These  include  uncertainties  relating  to  competition  and
technological change, intellectual property rights and litigation, dependence on
certain key industries and the possible effects of changes in regulations, risks
associated with the company's acquisition strategy and international operations,
and risks  associated  with the potential  impact of the year 2000 on processing
date-sensitive information.
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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):

                                  July 21, 1998

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

                             THERMOQUEST CORPORATION
             (Exact name of Registrant as specified in its charter)

Delaware                      1-14262                       77-0407461
(State or other              (Commission               (I.R.S. Employer
jurisdiction of               File Number)             Identification Number) 
incorporation or
organization)

2215 Grand Avenue Parkway
Austin, Texas                                                   78728-3812
(Address of principal executive offices)                         (Zip Code)

                                (512) 251-1400
                         (Registrant's telephone number
                              including area code)
Item 5.     Other Events

      On July 21, 1998,  ThermoQuest  Corporation (the "Company") issued a press
release,  attached hereto as Exhibit 99, regarding its expected operating income
for the quarter ended July 4, 1998.

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 July 21,
                  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 22nd day of July, 1998.

                                    THERMOQUEST CORPORATION

                                    By: /s/ Sandra L. Lambert
                                          Sandra L. Lambert
                                          Secretary
EXHIBIT 99

                 THERMOQUEST EXPECTS SECOND QUARTER OPERATING
                     INCOME TO BE APPROXIMATELY $15 MILLION

AUSTIN,  Texas,  July 21, 1998 -- ThermoQuest  Corporation  (ASE-TMQ)  announced
today that it expects  operating  income for the second  quarter,  ended July 4,
1998, to be approximately $15 million.  As a result,  diluted earnings per share
for the 1998 quarter will be approximately $.16, compared with $.20 for the same
period in 1997.

      "We  experienced  lower-than-expected  revenues  primarily  due to  orders
received  late in the quarter,"  said Dr.  Richard W.K.  Chapman,  president and
chief  executive  officer of  ThermoQuest.  "We ended the second  quarter with a
backlog estimated to be $7 million higher than the first quarter of 1998."

      ThermoQuest  plans to release its complete  quarterly  earnings results on
August 10, 1998.

     ThermoQuest   Corporation   develops,    manufactures,   and   sells   mass
spectrometers,   liquid   chromatographs,   and  gas   chromatographs   for  the
environmental,  pharmaceutical,  and industrial  marketplaces.  These analytical
instruments are used in the  quantitative and qualitative  chemical  analysis of
organic and inorganic compounds at ultratrace levels of detection.  In addition,
the  company   manufactures   scientific   equipment  for  the  preparation  and
preservation  of  chemical  samples,  and  consumables  for  the  chromatography
industry.  ThermoQuest is a public subsidiary of Thermo Instrument Systems Inc.,
a Thermo  Electron  company.  More  information  is available on the Internet at
http://www.thermo.com/subsid/tmq1.html.

     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 3,  1998.  These  include  uncertainties  relating  to  competition  and
technological change, intellectual property rights and litigation, dependence on
certain key industries and the possible effects of changes in regulations, risks
associated with the company's acquisition strategy and international operations,
and risks  associated  with the potential  impact of the year 2000 on processing
date-sensitive information.