A series of microcosms were set up to verify the degradation pathway of CFC-113 in water under anaerobic conditions and to measure its half-life and that of its major degradation products HCFC-123a and chlorotrifluoroethene (CTFE). Anaerobic landfill leachate was used as a source of bacteria acclimated to chlorinated solvents. The rate of reaction in methanogenic leachate was also compared to that obtained in a buffer containing reduced hematin. In methanogenic landfill leachate, CFC-113 was transformed to HCFC-123a with a half-life of 5 days at 20°C. The same reaction occurred in sodium sulfide/cysteine buffers containing hematin, but at a much slower rate. The production of CTFE was independent of the presence of HCFC-123a and occurred abiotically. Under methanogenic conditions, HCFC-123a was found to be further dechlorinated to HCFC-133 and HCFC-133b. CTFE was found to be relatively stable in methanogenic landfill leachate but was decomposed rapidly in a buffer containing sulfide.