Abstract: In this study, peak output of our miniature fuel cell was raised to 420mW/cm 2 which is comparable to the conventional large scale fuel cells. We have proposed monolithically fabricated Si electrodes for miniature fuel cells, on which porous Pt catalyst layer and fuel channels are formed on a Si wafer. Although our past prototype cells demonstrated relatively high outputs among MEMS based miniature fuel cells, compared with conventional large scale cells, performance was poor. In this study, in order to make spatial non-uniformity of the cell structure conspicuous, reaction area of the fuel cell was reduced to 1mm 2 . Some cells showed high outputs though the majority showed little output. It was suggested that the adhesion between electrode chip and PEM (Polymer Electrolyte Membrane) was not tight. The electrode chip has a depression on the catalyst area. Two sheets of PEM were placed on the catalyst area to realize tight contact and increased output was obtained
