TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The catalyst comprises platinum (0.5 - 2)% and ruthenium (1 - 4)% based on the weight of the metal oxide carrier. In the catalyst, the mole ratio of platinum to ruthenium is 0.1 - 10 (preferably 0.3 - 3). The catalyst is prepared by a process involving: either a) impregnating a metal oxide in aqueous solution containing platinum ions and ruthenium ions having an amount so that the mixture oxide is subjected to incipient wetness impregnation, and b) heating the resulting impregnated mixture oxide so that only platinum and ruthenium ions in the aqueous solution are deposited on the metal oxide; or a1) immersing metal oxide in aqueous solution containing platinum ions and ruthenium ions; b1) adjusting pH value of the aqueous solution so that the platinum ions and ruthenium ions are adsorbed on surface of the metal oxide and adding a precipitation agent into the aqueous solution for precipitation of platinum and ruthenium ions on the metal oxide in a metal form; c1) separating the mixture of step (b1) by filtration to obtain metal oxide precipitated with platinum metal and ruthenium metal; and d1) heating the metal oxide precipitated with platinum metal and ruthenium metal. Preferred Method: The contacting is carried out at 200 - 350degreesC. The heating in step (b) involves drying the incipient wetness impregnated metal oxide at 100 - 150degreesC and calcining the dried metal oxide at 400 - 1000 (preferably 800 - 950)degreesC. The heating in step (d1) involves drying the metal oxide precipitated with platinum and ruthenium metal at 100 - 150degreesC and calcining the dried metal oxide at 400 - 1000 (preferably 800 - 950)degreesC. Preferred Components: The mixture gas comprises carbon monoxide at 0.1 - 2 (preferably less than 1)% based on the volume of the mixture gas. The concentration of carbon dioxide in the mixture gas is higher than a concentration of CO in the mixture gas. The amount of aqueous solution in step (a) or (a1) enables the metal oxide to be impregnated with 0.1 - 5% of platinum ions and 0.1 - 5% of ruthenium ions based on the weight of the metal oxide.    TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The metal oxide carrier is alumina, cerium dioxide, and/or zirconium oxide or their mixture oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The precipitation agent in step (b1) is hydrazine or formaldehyde. EXAMPLE - ZrO2 powder (30 g) was mixed with a solution of Ru(NO3)3 (50 g/l) containing ruthenium (0.306 g) and an aqueous solution of Pt(NO2)2(NH3)2 (50 g/l) containing platinum (0.294 g). The resulting mixture was diluted with deionized water to 110 ml and adjusted to pH of 9 - 10 by addition of sodium hydroxide for the platinum and ruthenium ions to be adsorbed onto ZrO2 carrier. Hydrazine (1.2 g) was then added to the mixture. The resulting mixture was stirred for 2 hours followed by filtration to obtain platinum- and ruthenium-containing ZrO2 powder. The ZrO2 powder containing platinum and ruthenium was dried at 120degreesC for 4 hours and calcined at 500degreesC for 2 hours to form platinum-ruthenium/ZrO2 catalyst (test) that contained 0.98 wt.% of platinum and 1.02 wt.% of ruthenium based on the weight of ZrO2 and had atomic ratio of platinum and ruthenium of 1:2. A control catalyst was prepared by: mixing ZrO2 powder (30 g) with Ru(NO3)3 solution (50 g/l) containing ruthenium (0.3 g); diluting the resulting mixture to 100 ml and adjusting to pH of 9 - 10 by addition of sodium hydroxide for the ruthenium ions to be adsorbed onto ZrO2 carrier, followed by adding hydrazine (1 g); stirring the mixture for 2 hours and filtering to obtain Ru-containing ZrO2 powder which was dried at 120degreesC for 4 hours and calcined at 500degreesC for 2 hours to obtain Ru/ZrO2 catalyst (control) containing ruthenium (1 wt.%) based on the weight of ZrO2 carrier. A conventional fixed-bed reaction system was used to test the activity of the test/control catalyst in methanation reaction. The honeycomb catalysts were separately mounted in quartz reaction tube with inside diameter of 2.2 cm. An electric heating furnace was used to control inlet temperature of the reaction mixture gas. The reaction mixture gas contained hydrogen (50 vol.%), carbon monoxide (2 vol.%), carbon dioxide (18 vol.%), water (12 vol.%), and the balance of nitrogen. The flow rate of the mixture gas was 938 ml/minute. The carbon monoxide ratio in the methanation reaction versus inlet temperature of the reaction mixture gas was determined. It was observed that in test method, the addition of platinum improved the performance of the Ru/ZrO2 catalyst in carbon monoxide methanation reaction as compared to the control method. The carbon monoxide conversion ratio of the control Ru/ZrO2 catalyst at 300degreesC was about 57%, and of the test catalyst was 76%. The results showed that the test method carried out using platinum-ruthenium/ZrO2 catalyst provided improved conversion of carbon monoxide as compared to the control method carried out without using platinum in the catalyst.