Abstract The reaction of 2-chloroethyl ethyl sulfide was investigated in several oil-in-water microemulsions. The reaction products were identified by GC/MS, NMR, and LC/MS, and the reaction process was monitored by measuring peak height of reaction products and 2-chloroethyl ethyl sulfide with time by 1H NMR spectroscopy. The result showed that 2-chloroethyl ethyl sulfide degraded to 2-hydroxyethyl