NOVELTY - A high activity water gas shift catalyst system comprises a support consisting of cerium oxide, a mixed metal oxide of cerium oxide-zirconium oxide or a mixed metal oxide of cerium oxide-lanthanum oxide; and an anti-methanation agent comprising copper compound, manganese compound and/or iron compound. The high activity water gas shift catalyst system has no methane formation at 200-350degreesC.    USE - For use in reducing the amount of carbon monoxide in process fuel gas in a water gas shift converter (claimed) for generating hydrogen.    ADVANTAGE - There is no methane formation at 200-600degreesC. The anti-methanation agent reduces or even eliminates methanation (conversion to methane formation).    DETAILED DESCRIPTION - A high activity water gas shift catalyst system comprises a noble metal; a support consisting of cerium oxide or a mixed metal oxide of cerium oxide-zirconium oxide, wherein the cerium oxide is 80-20 wt.% of total metal oxide and the zirconium oxide is 20-80 wt.% of total metal oxide, or a mixed metal oxide of cerium oxide-lanthanum oxide, wherein cerium oxide is 80-20 wt.% of total metal oxide and lanthanum oxide is 20-80 wt.% total metal oxide; an anti-methanation agent comprising copper compound, manganese compound and/or iron compound; and optionally a promoter comprising alkali metal(s) or alkaline earth metal(s). The high activity water gas shift catalyst system has no methane formation at 200-350degreesC. An INDEPENDENT CLAIM is also included for a method of reducing an amount of carbon monoxide in process fuel gas in a water gas shift converter comprising placing a high activity water gas shift catalyst system into a water gas shift converter; and passing the process fuel gas through the water gas shift converter in effective contact with the high activity water gas shift catalyst system and converting a portion of the carbon monoxide in the process fuel gas into carbon dioxide and hydrogen by a water gas shift reaction with no methane formation at 200-350degreesC.