Sulfuryl chloride and thionyl chloride have been found to be new chlorinating agents for alkyl sulfides. All nine of the possible chlorinated dimethyl sulfides have been prepared by chlorination of dimethyl sulfide and trithiane with sulfuryl chloride. Thionyl chloride is a less vigorous chlorinating agent than sulfuryl chloride, but it affords good yields of mono-, di-and trichlorcdimethyl sulfides from dimethyl sulfide, and almost a quantitative yield of a, a'- ...