We demonstrate a monolithic polymer electrolyte membrane fuel cell by integrating a narrow (200 mu m) Nafion strip in a molded polydimethylsiloxane (PDMS) structure. We propose two designs, based on two 200 mu m-wide and two 80 mu m-wide parallel microfluidic channels, sandwiching the Nafion strip, respectively. Clamping the PDMS/Nafion assembly with a glass chip that has catalyst-covered Au electrodes, results in a leak-tight fuel cell with stable electrical output. Using 1 M CH3OH in 0.5 M H2SO4 solution as fuel in the anodic channel, we compare the performance of (1) O-2-saturated 0.5 M H2SO4 and (II) 0.01 M H2O2 in 0.5 M H2SO4 oxidant solutions in the cathodic channel. For the 200 mu m channel width, the fuel cell has a maximum power density of 0.5 mW cm(-2) and 1.5 mW cm(-2) at room temperature, for oxidants I and II, respectively, with fuel and oxidant flow rates in the 50-160 mu L min(-1) range. A maximum power density of 3.0 mW cm(-2) is obtained, using oxidant II for the chip with 80 mu m-wide channel. due to an improved design that reduces oxidant and fuel depletion effects near the electrodes. (C) 2009 Elsevier B.V. All rights reserved.