NOVELTY - Oxidizing carbon monoxide to carbon dioxide involves: contacting feed stream containing carbon monoxide, hydrogen and oxygen with composition containing platinum and iron at 60 - 100degreesC, until composition is at least partially deactivated; increasing temperature and contacting feed with deactivated composition at 120 - 250degreesC to form at least partially regenerated composition; and decreasing temperature and contacting feed with regenerated composition at 60 - 100degreesC.    USE - For oxidizing carbon monoxide to carbon dioxide (claimed), for removing carbon monoxide from a stream containing carbon monoxide and hydrogen to provide hydrogen feedstock for the fuel cells.    ADVANTAGE - The method provides a selective oxidation of carbon monoxide to carbon dioxide in hydrogen-rich streams; along with the regeneration of the catalyst composition. The method removes carbon monoxide to a level necessary to prevent the poisoning of the catalyst in the hydrogen-air polymer electrolyte membrane (PEM) fuel cell stack, and allows the regeneration of the catalyst composition and further conversion of carbon monoxide to carbon dioxide to provide hydrogen feedstock for fuel cells on a level of carbon monoxide removal that is commercially viable. The catalytic composition is the same as that used in carbon dioxide lasers.    DETAILED DESCRIPTION - Oxidizing carbon monoxide with oxygen to carbon dioxide involves:    (a) contacting a feed stream containing carbon monoxide, hydrogen and oxygen with a composition containing platinum and iron in a contacting zone at an operating temperature of 60 - 100degreesC, to produce a product stream containing less carbon monoxide than the feed stream, for a prolonged period until the composition is at least partially deactivated;    (b) increasing the temperature of the contacting zone and contacting the feed stream with the at least partially deactivated composition at a regeneration temperature of 120 - 250degreesC to form at least partially regenerated composition; and    (c) decreasing the temperature of the contacting zone and contacting the feed stream with the regenerated composition at the operating temperature of 60 - 100degreesC.