Gold deposited on sulfated TiO2-ZrO2 with sodium hydroxide existed in the form of isotropic particles of 11 nm or less in diameter, whereas deposition with aqueous ammonia yielded larger anisotropic crystallites. The gold on sulfated TiO2-ZrO2 catalyst prepared by deposition with sodium hydroxide was active for the oxidation of carbon monoxide at room temperature in the presence of water vapor. However, the selectivity of the catalysts to carbon dioxide during the decomposition of chlorodifluoromethane in the presence of water vapor was increased by only a small extent compared to those without gold nanoparticles. The gold nanoparticles were deactivated for CO oxidation by HF and HCl formed during the hydrolysis of HCFC-22.