Abstract: An improved process for purifying thionyl chloride by the double distillation of an impure mixture of thionyl chloride, sulfuryl chloride, sulfur monochloride, sulfur dichloride and sulfur dioxide is disclosed. The double distillation process is conducted in the presence of sulfur to convert sulfur dichloride into sulfur monochloride. The sulfuryl chloride content of the mixture is reduced by contacting the vapor from the reboiler in the first stage distillation with activated carbon prior to fractional distillation in the column. The product of the first stage distillation is then redistilled to produce a thionyl chloride product of high purity.