Supported vanadia-alumina and vanadia-titania catalysts with and without molybdena modifier were synthesized, characterized and studied for the propane ODH reaction. In these catalysts the surface molybdena species is present as a non-interacting phase and possesses a much lower activity compared to the surface vanadia species. The propane ODH reaction studies reveal that molybdena modified vanadia catalysts are more active and selective for propene formation compared to the unmodified vanadia catalysts. This promotional effect appears to be due to the increase in propane adsorption in the presence of molybdena as observed by FTIR spectroscopy.