Work in our laboratory has focused on decomposition of organosulfides using Mo and V in heterogeneous catalysis. This class of compounds consists of several noxious and environmentally hazardous chemicals, including the blister agent bis-(2-chloroethyl)sulfide (mustard gas). We have recently shown that V-doped APMS (acid-prepared mesoporous spheres) are active for the oxidation of the mustard gas analogue 2-chloroethyl ethyl sulfide (CEES) to its sulfoxide and sulfone (CEESO and CEESO₂). Selectivity for the sulfoxide is important because it is non-toxic, in contrast to the sulfone. This presentation will include a summary of our work to date in this area, including new data on V-APMS showing nearly quantitative and selective conversion of CEES. Characterization of APMS doped with Mo, V, and the polyoxometalate H₅Mo₁₀V₂O₄₀ ("POM") by XRD, ²⁹Si and ⁵¹V NMR, IR, TEM, EPR, and EXAFS will also be presented. This data highlights the important role of isolated metal species in this process, as opposed to metal oxide nanoparticles and bulk metal oxides that form at higher metal loadings. This is consistent with results from thermal studies on CEES oxidation with V-APMS, which show somewhat different thermodynamic and kinetic parameters when isolated vanadyls are present versus vanadium oxide nanoparticles. The results of a temperature-based study to determine the thermodynamic and kinetic parameters for the oxidation will also be presented. Finally, preliminary data on the oxidation of CEES using V-APMS and POM-APMS in fluorinated solvents will be shown, with the goal of producing a catalytic system capable of recycling fluorinated wash solvents containing organosulfides.