Carbon dioxide and water vapor were effectively photoconverted to methane using either pure or modified-TiO₂ and UV-Vis irradiation. The process of photoconversion in the gas phase was carried out in a tubular reactor equipped with a perforated TiO₂-coated support. The effect of selected parameters of TiO₂ immobilization procedure, such as the time and temperature of drying step and the photocatalyst amount, on photocatalytic efficiency was investigated. The effect of TiO₂ loading with Ag/Au nanoparticles on CO₂ photoconversion efficiency was also studied. CH₄ was found to be the major photoreduction product. The highest methane production was observed after irradiation of CO₂+H₂O mixture over Au-TiO₂ photocatalyst. After one hour of UV-Vis irradiation 503 ppm of methane was formed.