A simple modified sol-gel method by calcinating titanium dioxide precursor with gold and lanthanum in heat treatment under H-2/CO2 atmosphere has been proposed to prepare highly photocatalytic Au-La2O3/TiO2 (ALT) hybrid. Characterization results show that gold nanoparticles with small particle size are embedded in a nearly homogeneous component, which may induce a strong interaction of La and Au co-doping to obtain an appropriately modified bandgap structure and extend the absorption edge to visible light region. The formation of La2O2CO3 on the surface could facilitate to the basicity optimization of the photocatalyst and contribute to the C-H bond cleavage in HCOO- to release H-2 and CO2 from formic acid (FA). The large surface area and small sized mesopores structure could provide more active sites for the adsorption of reactant molecules and improve the photocatalytic activity. Benefiting from these positive effects, the ALT photocatalyst calcinating in H-2/CO2 demonstrated a great potential in FA photocatalytic decomposition under simulated sunlight irradiation and produced an optimal H-2 generation rate of 178.4 runol g(cat)(-1) h(-1) (14.9 mmol g(Au)(-1) h(-1)), which was approximately 1.3, 1.9 and 2.6 times higher than the same catalysts calcinating in H-2, CO2, and N-2, respectively.