Deaerated suspensions of arsenic in trichlorotrifluoroethane were irradiated in a60Co radiation facility. After treating the irradiated samples with sodium hydroxide solution the yields of chloride and fluoride were determined. By gaschromaloyruphy the yield of C4F6Cl4was measured quantitatively. The yields of chloride and fluoride proved to be linear functions of the applied radiation dose. The dependence of the chloride, fluoride and C4F6Cl4yields from the amount of arsenic added to a fixed quantity of C2F3Cl3was studied. The experimental results were interpreted by a radical reaction mechanism.