Abstract: Disclosed is a fuel composition for fuel cells with improved performance. In order to efficiently remove undesirable intermediates of a fuel cell that uses liquid oxygenated hydrocarbons as fuel thereof, polyoxometalate as an oxidation assistant is directly added to the fuel cell. Herein, polyoxometalate includes at least one redox reactive anion caused by dissolution of polyoxometalate in an organic medium containing solution and/or an aqueous solution. The intermediates generated during activating the fuel cell are efficiently oxidized and, additionally, carbon monoxide with the property of catalyst poisoning of electrode catalyst is eliminated, thereby accomplishing improvements in poisoning resistance of the catalyst and, in turn, performance of the fuel cell.