A reverse (water in oil) microemulsion has been designed to oxidize hydrophobic organic substrates with singlet oxygen (O-1(2), (1) Delta(g)) generated from the disproportionation of hydrogen peroxide catalyzed by molybdate ions. The microemulsion was prepared by mixing methylene chloride, sodium dodecylsulfate, n-butanol, and aqueous molybdate. Flash photolysis studies have shown that in such media singlet oxygen exhibits a similar kinetic behavior that under homogeneous conditions (tau(Delta) approximate to 42 mu s). Various typical organic substrates have been oxidized on the preparative scale with this chemically generated singlet oxygen, and the expected oxidation products have been isolated in high yields.