A simple, efficient and highly chemoselective method has been developed for the synthesis of sulfoxides from sulfides using N-t-butyl-N-chlorocyanamide as an oxidant in a mixed acetonitrile-water solution with a 1: 1 mol ratio of oxidant to sulfides. N-t-butyl-N-chlorocyanamide, a source of positive chlorine, has been used for conversion of the variety of sulfides into their corresponding sulfoxides in quantitative yields.