<PAGE>   1


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   FORM 10-Q/A

[X]              QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                 For the quarterly period ended June 30, 1996.

                                       OR

[ ]           TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                For the transition period from ________ to _______


                         Commission file number 0-21042
                                                -------

                          Molten Metal Technology, Inc.
                          -----------------------------
             (Exact name of registrant as specified in its charter)


              Delaware                                  52-1659959
  (State or other jurisdiction of          (I.R.S. Employer Identification No.)
   incorporation or organization)


        400-2 Totten Pond Road
              Waltham, MA                                   02154
              -----------                                   -----
(Address of principal executive offices)                  (Zip Code)


Registrant's telephone number, including area code:      (617) 487-9700


Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months, and (2) has been subject to such filing requirements
for the past 90 days.

                                    YES  X   NO
                                        ---     ---

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the latest practicable date.


  Common Stock, $.01 par value                             23,487,252
  ----------------------------                   ------------------------------
              Class                              Outstanding at August 12, 1996


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                 MOLTEN METAL TECHNOLOGY, INC. AND SUBSIDIARIES
<TABLE>

                           CONSOLIDATED BALANCE SHEET
<CAPTION>

                                                                             JUNE 30,       DECEMBER 31,
                                                                               1996            1995
                                                                               ----            ----

<S>                                                                       <C>               <C>         
ASSETS

Current assets:
  Cash and cash equivalents                                               $ 66,595,865      $  6,644,856
  Short-term investments                                                   129,686,444        79,631,394
  Accounts receivable                                                        4,932,092         1,917,858
  Accounts receivable from affiliate                                        28,628,439        15,412,196
  Prepaid expenses and other current assets                                  5,592,865         2,309,398
                                                                          ------------      ------------
          Total current assets                                             235,435,705       105,915,702

Restricted cash and investments                                              5,762,234         7,432,817
Fixed assets, net                                                           45,394,739        34,679,390
Intangible assets, net                                                       4,440,476         3,501,680
Investment in affiliate                                                     13,281,417           834,794
Other assets                                                                 5,695,976           971,618
                                                                          ------------      ------------
                                                                          $310,010,547      $153,336,001
                                                                          ============      ============

LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities:
  Current portion of long-term debt                                       $    194,321      $    195,043
  Accounts payable                                                           7,474,143         9,827,490
  Accrued expenses                                                           2,988,663         1,713,557
  Accrued interest                                                           2,107,154           789,455
  Deferred revenue from affiliate                                              583,333         4,083,334
                                                                          ------------      ------------
          Total current liabilities                                         13,347,614        16,608,879
                                                                          ------------      ------------

Long-term debt                                                             166,539,092        22,883,962
                                                                          ------------      ------------
Due to related parties                                                       1,385,889         1,474,586
                                                                          ------------      ------------
Deferred income from affiliate                                               4,604,793         2,459,918
                                                                          ------------      ------------

Stockholders' equity:
  Preferred stock, $.01 par value, 3,000 shares authorized, no shares
     issued or outstanding                                                        --                --
  Common stock, $.01 par value, 100,000,000 shares authorized;
     shares issued and outstanding: 23,467,466 at June 30, 1996 and
      22,746,854 at December 31, 1995                                          234,675           227,469
  Additional paid-in capital                                               158,974,939       146,631,297
  Valuation allowance for short-term investments                              (737,071)         (311,163)
  Accumulated deficit                                                      (34,339,384)      (36,638,947)
                                                                          ------------      ------------
          Total stockholders' equity                                       124,133,159       109,908,656
                                                                          ------------      ------------
                                                                          $310,010,547      $153,336,001
                                                                          ============      ============
</TABLE>

                       See notes to financial statements.


                                       3

<PAGE>   3

                 MOLTEN METAL TECHNOLOGY, INC. AND SUBSIDIARIES

<TABLE>

                                               CONSOLIDATED STATEMENT OF OPERATIONS

<CAPTION>

                                                                           QUARTER ENDED JUNE 30,        SIX MONTHS ENDED JUNE 30,
                                                                        ---------------------------     ---------------------------
                                                                            1996            1995            1996            1995
                                                                            ----            ----            ----            ----

<S>                                                                     <C>             <C>             <C>             <C>        
Revenue:
    Research and development ("R&D")                                    $ 3,785,488     $ 4,034,471     $ 5,043,297     $ 6,676,665
    Construction, R&D and consulting from affiliate                      12,911,227       1,687,071      30,276,963       1,920,574
    Technology transfer and success fees from affiliate                   3,750,000       1,750,000       7,500,000       3,500,000
                                                                        -----------     -----------     -----------     -----------
                                                                         20,446,715       7,471,542      42,820,260      12,097,239
Operating expenses:
    Cost of revenue - R&D                                                 3,724,952       4,034,472       4,903,283       6,676,665
    Cost of revenue - construction, R&D and consulting from affiliate    10,669,969       1,589,023      25,814,910       1,840,497
    R&D                                                                   4,618,838       2,206,398       9,327,001       5,893,853
    Selling, general and administrative ("SG&A")                          2,210,886       1,136,581       4,629,218       3,078,102
                                                                        -----------     -----------     -----------     -----------
                                                                         21,224,645       8,966,474      44,674,412      17,489,117
Equity income from affiliate                                              2,306,724         183,378       2,676,036         183,378
                                                                        -----------     -----------     -----------     -----------
Income (loss) from operations                                             1,528,794      (1,311,554)        821,884      (5,208,500)
                                                                        -----------     -----------     -----------     -----------

Other income (expense):
    Interest income                                                       2,230,649       1,380,013       3,585,378       2,752,287
    Interest expense                                                     (1,675,308)       (436,169)     (2,107,699)       (915,289)
                                                                        -----------     -----------     -----------     -----------
Net income (loss)                                                       $ 2,084,135     $  (367,710)    $ 2,299,563     $(3,371,502)
                                                                        ===========     ===========     ===========     =========== 

Net income (loss) per share                                             $      0.08     $     (0.02)    $      0.08     $     (0.15)
                                                                        ===========     ===========     ===========     =========== 

Weighted average common and common equivalent
 shares outstanding                                                      27,743,802      22,250,060      27,619,150      22,225,888
                                                                        ===========     ===========     ===========     =========== 

</TABLE>

                       See notes to financial statements.


                                       4

<PAGE>   4

                 MOLTEN METAL TECHNOLOGY, INC. AND SUBSIDIARIES

<TABLE>

                               CONSOLIDATED STATEMENT OF CASH FLOWS
<CAPTION>

                                                                                  SIX MONTHS ENDED JUNE 30,
                                                                              ----------------------------------
                                                                                  1996                 1995
                                                                                  ----                 ----

<S>                                                                           <C>                   <C>         
Cash flows from operating activities:
 Net income (loss)                                                            $  2,299,563          $(3,371,502)
Adjustments to reconcile net income (loss) to net cash used in
operating activities:
   Depreciation and amortization                                                 2,750,868            2,368,763
   Equity income from affiliate                                                 (2,676,036)            (183,378)
   Compensation expense related to common stock options                            120,903               31,248
   Increase in accounts receivable                                              (3,014,234)            (759,110)
   Increase in accounts receivable from affiliate                              (13,216,243)          (1,401,609)
   Increase in prepaid expenses and other current assets                        (3,283,467)          (1,507,386)
   Decrease (increase) in other assets                                            (411,846)              65,589
   Increase (decrease) in accounts payable                                      (2,353,347)           1,162,936
   Increase in accrued expenses                                                  1,275,106            1,842,320
   Increase (decrease) in accrued interest                                       1,317,699               (6,365)
   Decrease in deferred revenue                                                 (3,500,001)          (3,657,189)
   Increase in deferred income from affiliate                                    2,144,875              135,048
                                                                              ------------          ----------- 
       Net cash used in operating activities                                   (18,546,160)          (5,280,635)
                                                                              ------------          ----------- 

Cash flows from investing activities:
  Purchase of fixed assets                                                     (13,251,320)          (6,173,189)
  Purchase of intangible assets                                                 (1,055,031)            (404,467)
  Redemption (purchase) of short-term investments, net                         (50,480,958)          19,607,650
  Decrease in restricted cash                                                    1,670,583            1,574,068
                                                                              ------------          ----------- 
      Net cash provided by (used in) investing activities                      (63,116,726)          14,604,062
                                                                              ------------          ----------- 

Cash flows from financing activities:
  Proceeds from issuances of common stock                                        2,459,358              621,660
  Net proceeds from issuance of long-term debt                                 139,338,826                   --
  Payments to related parties                                                      (88,697)                  --
  Principal repayments of long-term debt                                           (95,592)            (192,731)
                                                                              ------------          ----------- 
      Net cash provided by financing activities                                141,613,895              428,929
                                                                              ------------          ----------- 
Increase in cash and cash equivalents                                           59,951,009            9,752,356
Cash and cash equivalents at beginning of period                                 6,644,856           12,063,883
                                                                              ------------          ----------- 
Cash and cash equivalents at end of period                                    $ 66,595,865          $21,816,239
                                                                              ============          ===========

Additional disclosure of non-cash investing and financing activities:  
Issuance of common stock in exchange for investment in affiliate              $  9,770,587          $        --
                                                                              ============          ===========  
</TABLE>

                       See notes to financial statements.


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<PAGE>   5


                 MOLTEN METAL TECHNOLOGY, INC. AND SUBSIDIARIES
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

NOTE 1. BASIS OF PRESENTATION

Molten Metal Technology, Inc. (the "Company") is an environmental technology
company commercializing pollution prevention and waste recycling methods that
are broadly applicable to a wide variety of hazardous, non-hazardous and
radioactive wastes. The Company developed its core technology, Catalytic
Extraction Processing ("CEP"), to dissolve waste compounds to their constituent
elements in a molten metal bath and reconfigure the elements into useful raw
materials.

The consolidated financial statements include the accounts of the Company and
its wholly owned subsidiaries. All significant intercompany balances and
transactions have been eliminated in consolidation.

Net income (loss) per share is determined by dividing net income (loss) by the
weighted average number of common and common equivalent shares outstanding
during the period. Common share equivalents consist of common stock which may be
issuable upon exercise of outstanding stock options and warrants. Common share
equivalents have been excluded from the weighted average number of common shares
in loss periods since their effect is anti-dilutive.

Certain reclassifications have been made for consistent presentation. The
reclassifications have no effect on the net loss for the periods ending June 30,
1995.

The information furnished is unaudited and reflects all adjustments (consisting
of only normal recurring adjustments) which, in the opinion of management, are
necessary for a fair presentation of the financial position and results of
operations for the interim periods. The accompanying financial statements should
be read in conjunction with the Company's audited financial statements and
related footnotes for the year ended December 31, 1995 which are included in the
Company's annual report on Form 10-K for the year ended December 31, 1995. The
results of operations for the periods ended June 30, 1996 are not necessarily
indicative of the results to be expected for the full year.

NOTE 2. EQUITY TRANSACTIONS

During the quarter ended June 30, 1996, 94,351 shares of common stock were
issued upon the exercise of options.

In April 1996, the Company and Lockheed Martin Corporation ("LMC") closed an
agreement to expand their partnership (M4 Environmental L.P. or "M4") through
the acquisition by M4 of the Retech division of Lockheed Environmental Systems &


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Technologies Co., an indirect wholly-owned subsidiary of LMC. The Retech
division designs and manufactures metallurgical equipment and waste processing
systems that utilize a plasma technology. Under this agreement, LMC contributed
approximately half of the assets of the Retech division to M4, and the Company
purchased substantially all of the remaining assets of the Retech division for
307,735 shares of its common stock, and then immediately contributed these
assets to M4. Pursuant to the agreement, the number of shares issued to LMC will
be adjusted when the value of net contributions from LMC to Retech is
determined.

NOTE 3. CONVERTIBLE DEBT

In May 1996, the Company issued $143,750,000 of Convertible Subordinated Notes
Due 2006 (the "Notes"). The Notes have a term of ten years and are payable in
full on May 1, 2006. The Notes bear interest at the rate of 5.50% per year
payable semi-annually. The Notes are convertible into shares of the Company's
common stock at a conversion price of $38.75 per share.

NOTE 4. NEW ACCOUNTING PRONOUNCEMENT

Effective January 1, 1996, the Company adopted Statement of Financial Accounting
Standards No. 121, `Accounting for the Impairment of Long-Lived Assets and for
Long-Lived Assets to Be Disposed Of' ("FAS 121"). In accordance with this
standard, the Company periodically assesses whether any events or changes in
circumstances have occurred that would indicate that the carrying amount of a
long-lived asset may not be recoverable. If such an event or change in
circumstance occurs, the Company will evaluate whether the carrying amount of
such assets is recoverable by comparing the net book value of the assets to
estimated future undiscounted cash flows, excluding interest charges,
attributable to such assets. If it is determined that the carrying amount is not
recoverable, the Company will recognize an impairment loss equal to the excess
of the carrying amount of the asset over its fair value. Adoption of FAS 121 did
not have an impact on the Company's financial statements.



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<PAGE>   7


                                   SIGNATURES

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



                                          MOLTEN METAL TECHNOLOGY, INC.
                                          -----------------------------



Date:  November 18, 1996              By: /s/ Benjamin T. Downs
       -----------------                  ---------------------
                                          Benjamin T. Downs
                                          Executive Vice President of Finance
                                          and Administration, Treasurer
                                          (Principal Financial Officer and
                                          Authorized Signatory)



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