InNbO 4 was prepared by the solid-state reaction method. Various cocatalysts were added on InNbO 4 by the incipient-wetness impregnation method. The effects of co-catalyst and pretreatment conditions on the photocatalytic activity of InNbO 4 for photoreduction of carbon dioxide were investigated. NiOInNbO 4 and Co 3O 4InNbO 4 were pretreated by reduction at 500°C for 2 h and subsequent oxidation at 200°C for 1 h. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UVvis diffuse reflectance spectroscopy. The characterization results of NiOInNbO 4 catalysts after pretreatment showed the presence of highly crystalline NiO and monoclinic Nb 2O 5. NiOInNbO 4 with reductionoxidation pretreatment exhibited the highest activity due to the presence of coreshell type Ni 0 and NiO on the surface and the presence of a small amount of Nb 2O 5 as a promoter.