Transition metal oxide catalysts tend to deactivate in the presence of moisture during hydrogen purification using preferential oxidation (PROX) of carbon monoxide (CO) . Thus, novel water-tolerant catalysts need to be developed. Herein, the evolution of heat treated swellable organically-modified silica (SOMS), a hydrophobic organic-inorganic hybrid material, has been characterized and applied as a catalyst support for PROX under moisture-rich conditions. While the SOMS-supported cobalt manganese oxide was found to be inactive, drastic improvement in CO conversion was observed for heat treated SOMS (HSOMS) supported catalysts. From thermogravimetric analysis and NMR spectroscopy it was found that SOMS retains its structural properties and hydrophobicity up to 400 degrees C. The performance of these catalysts was improved upon using toluene as the impregnation solvent, which enhanced the support wettability and improved active site deposition. The catalyst supported on HSOMS-400 was found to be more water tolerant than a silica-supported catalyst due to Si-O-Si(CH3)(3) groups retained from hexamethyldisilazane (HMDS) derivatization of SOMS.