MeOH was synthesized by photocatalytic conversion of CO2 in H2O at room temp. under UVA irradn. (65 W/m(2)) in presence of Pt-activated SiO2-supported TiO2 catalysts. Six catalysts were prepd. by impregnation of corn. SiO2 with hexane soln. of Ti(OCHMe2)(4), drying and calcination at 500-900 degrees C for 4 h in O-2. The activation of the catalysts with Pt was carried out by addition of H-2(PtCl6)center dot 9 H2O, drying, calcination at 500 degrees C for 4 h and redn. with H-2 at 300 degrees C for 4 h. The prepd. catalysts were studied by temp.-programmed redn., X-ray diffraction anal. and electron microscopy and then used for the MeOH synthesis. Only the 1%Pt/5%TiO2/SiO2 catalyst showed the expected activity in the MeOH synthesis.