This paper demonstrates a direct H2O2 fuel cell (DHPFC). The cell converts the energy released by H2O2 decomposition with H+ and OH- ions into electricity, and produces water and oxygen. In the experiment, we used a microfluidic cell, in which acid and alkaline electrolytes contact with each other. The measured power density of the cell is comparable to that of a typical air-breathing direct-methanol fuel cell. The DHPFC emits no CO2, uses simply handled aqueous fuels, and requires no expensive membrane-electrolyte assemblies. These advantages may allow the DHPFC to be a promising candidate for practical fuel cells. (C) 2004 The Electrochemical Society.