A preferential oxidation of CO remaining in reformed Hz fules(PROX) is one of the process to avoid a serious poisoning of anode-catalysts in fuel cells. Support screening studies have revealed NMO and alumina to be suitable for the prefernetial oxidation reaction within a temperature range of 130~230℃. The performance of a NMO supported 2.0wt％ Pt and Rh catalyst for the oxidative removal of CO from H₂-rich methane reformate(1％ CO, 65％ H₂, 10％ water) was investigated and compared to that of conventional catalysts In this paper, we present the results of selective CO oxidation in simulated reformate gas over Rh/NMO catalyst. The effect of water vapor, CO and oxygen concentration, temperature. and Rh loading on the activity and selectivity are presents. NMO appeared as a suitable support for the preferential CO oxidation catalyst at a wide temperature region.