In this study, hydrodechlorination of 1-chloro-1,1-difluoroethane (HCFC-142b) has been performed over palladium on activated carbon catalysts. Activated carbon was, prior to catalysts preparation, washed with sodium hydroxide and hydrofluoric acid and/or hydrochloric acid to remove the impurities. In this experiment effects of the H₂ reduction time and mloe ratio of H₂ to HCFC-142b on catalyst activities were investigated. The results showed that the conversion of HCFC-142b products were more than 20% and the selectivities to 1,1-difluoroethane