Abstract: KOH-modified TiO₂ support was obtained by treating the hydrolysate of tetrabutyl titanate with KOH solution of various concentrations; the gold catalyst supported on the KOH-modified TiO₂ was prepared through impregnation and used for CO oxidation. The support and catalyst were characterized by N₂ physical sorption, thermogravimetry, thermo-analysis, X-ray powder diffraction, UV-vis diffuse reflection spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results indicate that the modification with KOH may influence the structure and property of TiO₂ and Au/TiO₂ significantly. KOH modification can change electronic structure of TiO₂ and enhance the activity of Au/TiO₂ catalyst for low-temperature CO oxidation. However, the modification with excessive KOH may also block the porous structure of TiO₂ and weaken its adsorption ability, which leads an enlargement of gold particles on Au/TiO₂ and a decrease of its catalytic activity for CO oxidation.