<PAGE>
-----------------------------
OMB APPROVAL
-----------------------------
OMB Number: 3235-0145
Expires: December 31, 1997
Estimated average burden
hours per response......14.90
-----------------------------
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No.___________________)*
THERMATRIX, INC.
- --------------------------------------------------------------------------------
(Name of Issuer)
COMMON STOCK
- --------------------------------------------------------------------------------
(Title of Class of Securities)
883440-10-5
- --------------------------------------------------------------------------------
(CUSIP Number)
*The Remainder of this cover page shall be filled out for a reporting person's
initial filing of this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.
The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).
<PAGE>
- --------------------- -------------------
CUSIP No. 883550-10-5 13G Page __ of __ Pages
- --------------------- -------------------
- --------------------------------------------------------------------------------
1 NAME OF REPORTING PERSON
S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
VENTANA GLOBAL, LTD.
- --------------------------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) [X]
(b) [_]
- --------------------------------------------------------------------------------
3 SEC USE ONLY
- --------------------------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
ORANGE, CALIFORNIA
- --------------------------------------------------------------------------------
5 SOLE VOTING POWER
NUMBER OF 517,429
SHARES ----------------------------------------------------------------
BENEFICIALLY 6 SHARED VOTING POWER
OWNED BY
EACH ----------------------------------------------------------------
REPORTING 7 SOLE DISPOSITIVE POWER
PERSON WITH
517,429
----------------------------------------------------------------
8 SHARED DISPOSITIVE POWER
- --------------------------------------------------------------------------------
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
517,429
- --------------------------------------------------------------------------------
10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
N/A
- --------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
7.49%
- --------------------------------------------------------------------------------
12 TYPE OF REPORTING PERSON*
CORPORATION
- --------------------------------------------------------------------------------
*SEE INSTRUCTION BEFORE FILLING OUT
<PAGE>
CUSIP No. 833550-10-5 Page 4 of __ Pages
-----------
ITEM 1.
(a) Name of Issuer
THERMATRIX, INC.
(b) Address of Issuer's Principal Executive Offices
THERMATRIX, INC.
101 METRO DRIVE, SUITE 248
SAN JOSE, CA 95110
ITEM 2.
(a) Name of Person Filing
VENTANA GLOBAL, LTD.; MR. THOMAS O. GEPHART, CHAIRMAN
(b) Address of Principal Business Office or, if none, Residence
18881 VON KARMAN AVE., SUITE 1150
IRVINE, CA 92612
(c) Citizenship
U.S.
(d) Title of Class of Securities
COMMON STOCK
(e) CUSIP Number
883550-10-5
ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO RULE 13d-1(b), OR 13d-2(b), CHECK
WHETHER THE PERSON IS A:
(a) [_] Broker or Dealer registered under Section 15 of the Act
(b) [_] Bank as defined in section 3(a)(6) of the Act
(c) [_] Insurance Company as defined in section 3(a)(19) of the Act
(d) [_] Investment Company registered under section 8 of the Investment
Company Act
(e) [_] Investment Adviser registered under section 203 of the
Investment Advisers Act of 1940
(f) [_] Employee Benefit Plan, Pension Fund which is subject to the
provisions of the Employee Retirement Income Security Act of
1974 or Endowment Fund, see SS240.13d-1(b)(1)(ii)(F)
(g) [_] Parent Holding Company, in accordance with
SS240.13d-1(b)(ii)(G)(Note: See Item7)
(h) [_] Group, in accordance with SS240.13d-1(b)(1)(ii)(H)
ITEM 4. OWNERSHIP
(a) Amount beneficially Owned
571,429
(b) Percent of Class
7.49%
<PAGE>
CUSIP No. 833550-10-5 Page 5 of __ Pages
-----------
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote 571,429
(ii) shared power to vote or to direct the vote
(iii) sole power to dispose or direct the disposition of 571,429
(iv) shared power to dispose or direct the disposition of
ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
If this statement is being filed to report the fact that as of the date
hereof, the reporting person has ceased to be the beneficial owner of more than
five percent of the class of securities, check the following. [_]
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.
NOT APPLICABLE
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.
NOT APPLICABLE
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
NOT APPLICABLE
ITEM 9. NOTICE OF DISSOLUTION OF GROUP
NOT APPLICABLE
<PAGE>
CUSIP No. 833550-10-5 Page 6 of __ Pages
-----------
ITEM 10.
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired in the ordinary course of
business and were not acquired for the purpose of and do not have the effect of
changing or influencing the control of the issuer of such securities and were
not acquired in connection with or as a participant in any transaction having
such purposes or effect.
SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.
FEBRUARY 12, 1998
--------------------------------
Date
/s/ THOMAS O. GEPHART
--------------------------------
Signature
THOMAS O. GEPHART, CHAIRMAN,
--------------------------------
VENTANA GLOBAL LTD.
--------------------------------
Name/Title
