Cu-Al2O3-ZnO and supported precious metal catalysts were investigated for CO removal from reformed fuels. Supported Ru catalysts readily converted CO in the reformed fuel via formation of CH4, Supported Pt catalysts, especially Pt/Al2O3, under 200degreesC demonstrated high CO conversion (ca. 93%) without formation of methane. The Cu-Al2O3-ZnO catalyst also had a high activity (ca. 88%) comparable to that of Pt/Al2O3 without methanation under 200degreesC. CO removal by shift reaction was promoted for the catalysts with large adsorption of H2O. In concentrated CO conditions, the Cu-Al2O3-ZnO catalyst was superior to PUAl2O3 for CO removal due to high activity for the shift reaction. A small amount of oxygen (1.3%) added to reformed fuels accelerated the shift reaction over the Cu-Al2O3-ZnO catalyst. The additive effect is ascribed to thermal activation of the shift reaction with heat supplied by CO and H-2 Oxidation and to facilitating dissociation of adsorbed H2O with adsorbed oxygen. (C) 2003 Elsevier Science B.V. All rights reserved.