This work studied the design, fabrication, and performance evaluation of a 36 cm(2), passive, air-breathing, room-temperature, direct methanol fuel cell (DMFC). The cell is completely passive with no external pumps or other ancillary devices. It takes oxygen from the surrounding air, and the methanol solution is stored in a built-in reservoir. The fuel cell runs successfully with methanol concentration ranging from 0.5 to 4 M. It produced a power density of 11 mW cm(-2) reached with 4 M methanol at current densities as high as 36 mA cm(-2) and at a voltage of 0.3. (C) 2004 Elsevier B.V. All rights reserved.