TiO2-ZrO2 support containing 1:1 mole ratio was prepared by the coprecipitation method. TiO2 and ZrO2 were also prepared separately. After calcination at 823 K, the mixed oxide was found to be amorphous. These solids were impregnated with molybdenum and examined by laser Raman spectroscopy. Physical mixtures of MoO3 with the same supports were also studied. It is shown that monolayer structures of the molybdenum oxide overlayers are formed in the presence and absence of water vapour.