Supported vanadium and molybdenum oxide catalysts were prepared by reaction of the corresponding acetylacetonate complex in a non-aqueous solution with the surface hydroxyl groups of the carrier. Continuous or batch adsorption of the metal acetylacetonate from toluene, as well as wet impregnation from ethanol, resulted in a uniform coverage of the support. The applied metal oxide was probably present on the surface as a monomolecular dispersion. When readsorption or reimpregnation from toluene was carried out with TiO2 as support, metal oxide crystallites were formed, which could readily be detected with laser Raman spectroscopy. Reimpregnation from ethanol led to a complete occupancy of the surface hydroxyl groups of the carrier without the formation of metal oxide multilayers or crystallites.