Anionic micelles of sodium dodecyl sulfate (SDS) inhibit periodate ion oxidations of dipropyl and dibutyl sulfide (Pr2S and Bu2S) and of 1-methoxy-4-(methylthio)benzene (ArSMe), but there are residual reactions of micellar-bound sulfides at high [SDS] because IO4- is not completely excluded from the micellar surface. Concentrations of IO4- at surfaces of SDS micelles can be estimated based on a treatment of ion-micelle Coulombic interactions, and second-order rate constants, k2m, at the micellar surfaces can be calculated. These second-order rate constants are lower than those in water by factors of 2-6, but for reactions of Pr2S and ArSMe in cationic micelles of cetyltrimethylammonium chloride (CTACl) rate constants in micelles are lower than those in water by factors of 200-10(3). These differences are related to charge-charge interactions between the ionic micellar head groups and the developing positive charge on sulfur in the transition state. Rate constants of oxidation of the very hydrophilic ethanediol are unaffected by SDS.