TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The acid-treated catalyst is prepared by heating an impregnation mixture comprising impregnated support material, platinum impregnate, iron impregnate and solvent at 125-225 degreesC for 0.5-1.5 hours to partially drive off the solvent to provide dried catalyst mixture. The heating process is repeated one or more times. The dried catalyst mixture is heated to 100-600 degreesC for 0.5-1.5 hours in presence of oxygen containing gas to form oxidized catalyst mixture which is then heated in presence of hydrogen atmosphere to form reduced catalyst mixture. The reduced catalyst mixture is contacted with nitric acid to form acid-treated catalyst mixture. The acid-treated catalyst mixture is contacted with atmosphere containing free oxygen to form oxidized acid-treated catalyst mixture. The oxidized catalyst mixture may be contacted with hydrogen atmosphere at 200-400 degreesC for 2-4 hours to provide reduced, oxidized catalyst mixture. SPECIFIC MATERIALS - The support material is alumina or magnesium aluminate, preferably alumina.    EXAMPLE - 500 g of 1/8 inch alumina spheres Alcoa S-100 (RTM: activated alumina) was calcined at 800 degreesC for 16 hours. An impregnating solution obtained by dissolving 8.0 g of platinum (II) acetylacetonate (platinum (II) 2,4-pentanedionate) and 10.13 g of iron (III) acetylacetonate in 650 cc of acetone was sprayed on 400 g of dried, calcined alumina. The support was stirred frequently to assure even distribution of solution. When 1/4 of the impregnation solution had been applied to the support, the catalyst was placed in an oven and heated at 175 degreesC for 45 minutes to 1 hour to drive off the acetone. The catalyst was placed in air purged muffle furnace heated at 150 degreesC for 1 hour to obtain oxidized 1.0 weight percent platinum/0.4 wt.% iron on alumina as catalyst precursor. The catalyst precursor was reduced at 300degreesC with 200 cc/minute hydrogen gas for 3 hours. The reduced catalyst was poured into a large bowl and impregnated in a ventilated hood with 60 cc of concentrated nitric acid. The acid-treated catalyst was dried and calcined at 150 degreesC for 1 hour, 200 degreesC for 2 hours and 400 degreesC for 3 hours. The catalyst was then activated by reducing at 300 degreesC with 200 cc/minute hydrogen gas at atmospheric pressure for 3 hours to form activated, acid-treated catalyst. The obtained treated catalyst was contacted with gaseous mixture having mole ratio of oxygen to carbon monoxide of 0.8 at 80 degreesC. The amount of carbon monoxide converted into carbon dioxide was 100%. The selectivity of carbon dioxide was 51.7%.