Preferential CO oxidation in a H-2-rich stream over ZnO- and ZnO-Fe2O3-supported nanosize Au catalysts prepared by the deposition-precipitation method has been investigated. The reactant gas mixture contained 1% CO, 1% O-2, 40% H-2, 0-10% CO2, and 0-10% H2O, with the balance being He, at a total flow rate of 50 mL/min. The result showed that the Au/ZnO catalyst calcined at 500 degrees C displayed superior activity, giving complete CO conversion with the highest selectivity (similar to 75%) at 50 degrees C, whereas the Au/ZnO-Fe2O3 showed a marked improvement in activity under CO2 and H2O surroundings. In a two-stage reactor, it provided a comparable CO conversion and a better selectivity, about 10%, as compared to a single-stage reactor. The prepared catalysts were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance/ultra-violet-visible (DR/UV-vis) spectroscopy, and temperature-programmed reduction (TPR).