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Oxide-supported noble metal catalysts were tested in the preferential oxidation of carbon monoxide (PROX) reaction in the temperature range between 50 and 300°C. Both the influence of the noble metal nature (Pt, Ir, Pd), the support physical and chemical properties (redox, acidity, basicity) and the reaction conditions (oxygen stoichiometry) on the catalyst activity and selectivity was evaluated. Platinum and iridium were shown to be the most active and selective catalysts in the whole temperature range compared with palladium. Furthermore, noble metals supported over ceria-based oxides were shown to be active and selective, especially at low temperature. Additionally, it was observed that the higher the molar fraction in ceria in the oxide, the higher the activity and the selectivity in the PROX reaction. Ceria, with the highest oxygen mobility at the oxide surface, was shown to be the best support. Accordingly, on …