The polyoxometalate H5PV2Mo10O40 (1) supported on porous carbons forms selective and recoverable heterogeneous catalysts for the rapid room temperature oxidation of thioether mustard (HD) analogs. Both selectivities (95 to 99% for sulfoxide) and rates (similar to 20%) vary with the carbon support at parity of all other parameters. A 99% selectivity for the sulfoxide product, even at 75% conversion of the thioether substrate, is seen for the most selective system, 10 wt% 1 on Rohm and Haas Ambersorb (1/Ambersorb). Washing for 125 h in the solvent for catalysis, toluene, results in no significant loss in catalytic activity and a recovery and reusability study at high turnover also indicates that the catalysts are very stable. The polyoxometalate/carbon catalysts can be reactivated between uses by heating to similar to 80 degrees C. The oxidation of tetrahydrothiophene (THT) to THTO by tert-butylhydroperoxide (TBHP) catalyzed by 1/Ambersorb is first order in substrate and oxidant and proportional to the concentration of active sites on the 1/Ambersorb. The activation parameters for the process are Delta H double dagger = 11.4 +/- 0.05 kcal/mol and Delta S double dagger = -38.8 +/- 0.22 cal/K mol.