In this study, gallium-promoted copper-based catalysts prepared by impregnation methods on silica and ZnO supports. were examined for the hydrogenation of CO2 to methanol. The surface characteristics of catalysts depended on the support and were related to their catalytic performance. Silica-supported catalysts tested at reaction temperatures between 523 and 543 K were highly selective and stable. The selectivity to methanol was around 99%, the conversion to CO was very low and negligible amounts of hydrocarbons were formed. The use of hydrophobic silica enhanced the performance of the catalyst in terms of activity, selectivity and stability. The modification of properties of copper particles is related to the presence of very small particles of Ga2O3 on the surface. (C) 2001 Elsevier Science B.V. All rights reserved.