Alumina supported Pt group metal monolithic catalysts were investigated for selective oxidation of CO in hydrogen-rich methanol reforming gas for proton exchange membrane fuel cell (PEMFC) applications. The results are described and discussed in the present paper and show that Pt/gamma Al2O3 was the most promising candidate to selectively oxidize CO from an amount of about 1 vol% to less than 100 ppm. We have investigated the effect of the O-2 to CO feed ratio, the feed concentration of CO, the presence of H2O and/or CO2, and the space velocity on the activity, selectivity and stability of Pt/Al2O3 monolithic catalysts. Afterwards, the Pt/Al2O3 catalyst was scaled up and applied in 5 kW hydrogen producing systems based on methanol steam reforming and autothermal reforming. The hydrogen produced was then used as fuel for an integrated PEMFC. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.