The electroreduction of trichlorofluoromethane (CFC Ii) on lead cathodes, in combination with a hydrogen diffusion anode in an undivided cell using methanol-water mixtures at 15 degrees C, was studied by constant-current electrolytes. chronocoulometry , gas chromatography, scanning: electron microscopy, inductively coupled plasma, and energy dispersive X-ray microanalyses. The base electrolyte was a CFC-saturated methanol (70 vol %)-water mixture containing 0.75 mol dm(-3) NH4Cl. In this solution. and also with the addition of Cu2+ or tetrabutylammonium perchlorate, the current efficiently for the CFC Il electroreduction was about 96%. When PdCl2 was added to the base solution, Pd black was electrodeposited on Pb and the current efficiency decreased with time up to about 80% (smaller for MeOH concentrations less than or equal to 60 vol %). The current efficiencies found for additions of Fe3+ Al3+, or Zn2+ were also smaller. Under all conditions. the gas volume collected from the cathode increased with time. and dichlorofluoromethane was the main product in the eas and in the liquid. The use of electrodeposited, Pd black on the cathode slightly favored the formation of fluoromethane compared to chlorofluoromethane. in particular ut 200 mA cm(-2). The mechanism of the process. the effect of the cations employed, and the possibilities to increase the extent of CFC 11 electrodechlorination are discussed.