A novel proton exchange membrane fuel cell (PEMFC) anode which can facilitate the CO oxidation by air bleeding and reduce the direct combustion of hydrogen with oxygen within the electrode is described. This novel anode consists of placing Pt or An particles in the diffusion layer which is called Pt- or Au-refined diffusion layer. Thus, the chemical oxidation of CO occurs at Pt or An particles before it reaches the electrochemical catalyst layer when trace amount of oxygen is injected into the anode. All membrane electrode assemblies (MEAs) composed of Pt- or Au-refined diffusion layer do perform better than the traditionary MEA when 100 ppm CO/H-2 and 2% air are fed and have the performance as excellent as the traditionary NEA with neat hydrogen. Furthermore, CO tolerance of the MEAs composed of Au-refined diffusion layer was also assessed without oxygen injection. When 100 ppm CO/H-2, is fed, MEAs composed of Au-refined diffusion layer have the slightly better performance than traditionary MEA do because An particles in the diffusion layer have activity in the water gas shift (WGS) reaction at low temperature. (c) 2007 Elsevier B.V. All rights reserved.