Ambient temperature CO oxidation has been studied with Au/ZnO, Au/CuO and Au/CuO–ZnO catalysts prepared by a coprecipitation method. The catalysts are highly active for CO oxidation and are capable of sustained activity at 20°C. The highest activity is observed with Au/ZnO and this catalyst is shown, using transmission electron microscopy, to be comprised of smaller Au metal particles (2–5 nm) and a higher Au dispersion when compared with the other catalysts.