In view of the stringent CO intolerance of the proton-exchange membrane fuel cells (PEMFCs), it is essential to eliminate even trace amounts of carbon monoxide from the reformate streams. The preferential oxidation (PROX) is considered to be a promising method for CO cleaning up. Catalytic systems, based on copper supported on ceria-modified organized mesoporous alumina, were investigated for the PROX of CO in hydrogen-rich gas stream. The catalysts showed an interesting activity in the CO-PROX. The sample with the best catalytic performance was characterized by N-2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), temperature-programmed reduction by H-2 (H-2-TPR), and successive re-oxidation (TPO). (c) 2006 Elsevier B.V. All rights reserved.