A comparative study on ceria- and manganese oxide-supported gold catalysts for the oxidation of carbon monoxide at low temperature was investigated. Nanostructured gold catalysts supported on CeO2 and MnO2 were prepared by deposition-precipitation method. The influence of calcination temperatures before (200 degrees C and 400 degrees C and after (120 degrees C and 180 degrees C gold loading on CeO2 and the effect of crystalline nature on the catalytic activity of Au/MnO2 were also studied. The structure, morphology, and electronic properties of the catalysts were analyzed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. CeO2 prepared in this study was in nanosize range, which could confine the An particles in nanosize range. Fine dispersion of gold nanoparticles on CeO2 and MnO2 was confirmed. Existence of Au-0 and Au3+ states were noticed on Au/CeO2 catalysts, whereas only metallic gold was detected on Au/MnO2. The redox efficiency of CeO2 and MnO2 is responsible for high CO conversion at room temperature. Au/CeO2 (support was calcined at 400 degrees C and Au catalyst was calcined at 180 degrees C) demonstrates higher catalytic activity for CO oxidation than Au/MnO2. The co-existence of metallic and oxidized gold species on Au/CeO2 seems to be the main reason for the higher activity of AU/CeO2 with respect to Au/MnO2. (C) 2007 Elsevier B.V. All rights reserved.