Vanadium-doped acid prepared mesoporous spheres (V-APMS) were prepared with vanadium loadings of 1-40 wt% using a wet-impregnation method. The effects of vanadium loading on the support were studied using N-2 physisorption and powder XRD. The pore volumes, surface areas, and pore diameters of the catalysts decreased as a function of vanadium loading and diffraction peaks corresponding to crystalline V2O5 were detected by XRD at an intermediate V loading, becoming more intense as the V content increased. These results indicate that at low V loadings, the vanadium oxide species were well-dispersed on the silica; however, at higher V loadings crystalline V2O5 was,formed within the pores of the APMS. V-APMS was then studied as a heterogeneous catalyst for the oxidation of the chemical warfare agent stimulant 2-chloroethyl ethyl sulfide (CEES) using tert-butyl hydroperoxide (TBHP`) as the oxidant. Kinetic studies at temperatures ranging from 0 to 50 degrees C showed that materials with low V loadings were the most effective catalysts for the reaction. The mechanism of the oxidation reaction appeared to be different for catalysts that were composed of well-dispersed vanadium oxide species than for catalysts containing microcrystalline or crystalline V2O5. Finally, a possible reaction scheme for the oxidation of CEES by V-APMS is discussed. (c) 2007 Elsevier B.V. All rights reserved.