Abstract: A process for preparing trichloroethylene by chlorinating 1,2-dichloroethane in the liquid phase in the presence of ethylene followed by pyrolytic chlorination or dehydrochlorination of the reaction product. The 1,2-dichloroethane is chlorinated in the liquid phase in a bubble column reactor in the presence of 1 - 10 mole percent of ethylene with a chlorine/1.2-dichloroethane feed ratio of about 0.7 - 1.4/1, a temperature of about 40.degree. to 150.degree.C with superficial velocities exceeding 8 cm/sec. and gas dwell times of about 0.3 to 10 seconds. The chlorinated product is reacted in the gas phase with recirculated tetrachloroethanes and about 20 - 70 moles of chlorine per 100 moles of chlorinated hydrocarbons at temperatures of about 380.degree. to 500.degree.C and dwell times of about 20 to 30 seconds. This gas phase reaction product is separated by distillation into a low-boiling fraction containing predominantly dichloroethylenes and a high boiling fraction containing predominantly trichloroethylene.