o-Iodosobenzoate (1, IBA) and 2,3-iodosonaphthoate (2, INA) in aqueous cetyltrimethylammonium chloride ((CTA)Cl) micelles, as well as copper metallomicelles 14, all at pH 8, cleave phosphonothioates (11 and 12), the thiophosphate parathion (10), phosphonate 13, and phosphate 4 (paraoxon). The factors for the kinetic advantages in the cleavages of 12 and parathion range from 10(3) to 10(4). Although catalytic turnover of the iodoso reagents is not observed with the thio substrates and is slow with paraoxon, excess IBA/(CTA)Cl destroys paraoxon and parathion with reaction half-lives of 3.0 and 7.7 min, respectively, at pH 8.0 and 25 degrees C. The cleavages of 12 and parathion by IBA or INA involve an initial hydrolytic step followed by oxidation of the sulfur-containing fragment. Cleavages of 12 and parathion by o-iodoxybenzoate (1X, IBX) in (CTA)Cl micelles are much slower than the comparable reactions mediated by IBA, INA, and 14.