Copper- and gallium-doped titania photocatalysts prepared by means of sol-gel technique were comparatively evaluated with commercial TiO2 (P25) for the photo-reduction of carbon dioxide to formic acid. The laboratory-made Cu-x-Ga1-x/TiO2 nanocomposites have been thoroughly characterized in crystallographic, structural, morphological, and elemental composition analyses. XRD revealed photocatalysts owning the specific crystalline phases of anatase, beta-Ga2O3 and Cu2O, which allowed inferring on the doping phenomena of both transition and post-transition metals. The quasi-homogeneous deposition of a Ga and Cu layer has been identified from the TEM morphological characterization and the Brunauer-Emmett-Teller and Barrett-Joyner-Halenda techniques unveiled quantitative differences in textural properties among the mesoporous Ga- and Cu-doped titania photocatalysts by underlining a decrease of surface area when augmenting the gallium dose. The laboratory-made photocatalysts presented bandgaps higher than 3 eV and the DRS spectra underlined the optical absorption edge of the nanocomposites with a considerable shift to the visible light region. The elemental composition quantified by means of XPS reproduced the binding energies relative of Ti, Cu and Ga (2p(3/2), 2p(1/2)), and the K-edge XANES characterization confirmed the effective doping and modulation of the electronic properties of the laboratory-made photocatalysts. Several experimental runs have been carried out with Cu-0.78-Ga-0.22/TiO2 exhibiting the highest formic acid yields (394 mu mol/g(cat)) as well as superior quantum efficiency (49%) and selectivity (0.84). Accordingly, the photo-reduction of CO2 was considerably promoted by doping Ga and Cu into the titania substrate, which ultimately avoided the surface recombination of electron-hole pairs, thereby enhancing the photo-activity of Cu-x-Ga1-x/TiO2 nanocomposites. (c) 2012 Elsevier B.V. All rights reserved.