SEE RESTRICTIVE LEGEND ON REVERSE SIDE INCORPORATED UNDER THE LAWS OF DELAWARE No. **** Shares **** PERMA-FIX ENVIRONMENTAL SERVICES, INC. SERIES 11 CLASS K CONVERTIBLE PREFERRED STOCK Par Value $.001 Per Share THIS CERTIFIES THAT - - S P E C I M E N - - is the owner of **** *************** (******) shares of Series 11 Class K Convertible Preferred Stock of Perma-Fix Environmental Services, Inc. transferable only on the books of the Corporation by the holder hereof in person or by attorney upon surrender of this Certificate properly endorsed. In Witness Whereof, the said Corporation has caused this Certificate to be signed by its duly authorized officers and to be sealed with the Seal of the Corporation this ____ day of ________,1999. _____________________________ ______________________________ Secretary President SHARES $.001 EACH NEITHER THIS PREFERRED STOCK NOR ANY SHARES OF COMMON STOCK ISSUABLE UPON THE CONVERSION OF THIS PREFERRED STOCK HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT") OR QUALIFIED UNDER APPLICABLE STATE SECURITIES LAWS. THIS PREFERRED STOCK AND THE COMMON STOCK ISSUABLE UPON CONVERSION OF THIS PREFERRED STOCK MAY NOT BE OFFERED, SOLD, PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AND QUALIFICATION IN EFFECT WITH RESPECT THERETO UNDER THE SECURITIES ACT AND UNDER ANY APPLICABLE STATE SECURITIES LAW OR WITHOUT THE PRIOR WRITTEN CONSENT OF PERMA-FIX ENVIRONMENTAL SERVICES, INC. AND AN OPINION OF PERMA-FIX ENVIRONMENTAL SERVICES, INC.'S COUNSEL, OR AN OPINION FROM COUNSEL FOR THE HOLDER HEREOF, WHICH OPINION IS SATISFACTORY TO THE COMPANY, THAT SUCH REGISTRATION AND QUALIFICATION IS NOT REQUIRED UNDER APPLICABLE FEDERAL AND STATE SECURITIES LAWS OR AN EXEMPTION THEREFROM. ******************* CERTIFICATE FOR **** SHARES of the CAPITAL STOCK of Perma-Fix Environmental Services, Inc. Series 11 Class K Convertible Preferred Stock Par Value $.001 Per Share ISSUED TO **** S P E C I M E N **** DATED ___________, 1999 ******************** For Value Received, __________ hereby sell, assign and transfer unto __________________________________________________ ___________________ Shares of the Capital Stock represented by the within Certificate, and do hereby irrevocably constitute and appoint _________________________________________ to transfer the said Stock on the books of the within named Corporation with full power of substitution in the premises. Dated __________________, 19______. In presence of ________________________________________