Gold catalysts on mechanochemically prepared mixed ceria supports doped with FeOx and MnOx were studied in the reaction of preferential oxidation of CO in H-2 rich stream (PROX) in the presence of 20% CO2 and 10% H2O. The average size and the size distribution of gold particles were estimated by HRTEM. By means of XPS the Au XPS states at various binding energies, assigned to differently charged Au nanoparticles, were distinguished. The catalytic activity and selectivity in the oxidation of CO in dry H-2-reach stream was high, however the PROX activity was significantly suppressed by the addition of high concentrations of water and CO2. The two step calcinations of catalysts, first at 400 degrees C and then at 550 degrees C, showed no better performance in PROX reaction carried out at realistic experimental conditions. However, after the two-step calcination procedure, nanosized gold particles of high thermal stability were obtained over MnOx doped ceria. (C) 2011 Elsevier B. V. All rights reserved.