Biomass is of significant interest in the field of advanced energy engineering, including the use of woody biomass as an energy source. However, because cellulose-the major component of wood-is insoluble in most solvents, an excessive amount of energy and special procedures are required to convert woody materials into liquid and gaseous fuel. This report describes a biomass fuel cell that provides power densities on the order of 10 mWcm(-2) by direct utilization of wood sawdust and pulp as fuel. The fuel cell is simple, with H3PO4-impregnated raw materials located at the anode, and is operated at temperatures between 75 and 250 degrees C. Cellulose or its decomposition products reacted with H2O to form CO2, where the coulombic yield was approximately 95% at 150 degrees C or higher. Notably, the cell performance was superior to that of fuel cells with fuels ( partially oxidized or dehydrated monoto tetrasaccharides) obtained by an external treatment of cellulose with H3PO4. (C) 2017 The Electrochemical Society. All rights reserved.