This paper evaluates proton exchange membrane (PEM) fuel cell microchannel width and depths ranging from 20 mu m to 1000 mu m. A DRIE process is employed to create the serpentine microflow field patterns from silicon wafers for channel width and depths ranging from 20 mu m to 200 mu m. To compare the smaller microchannel dimensions with conventional dimensions, computer numerical control (CNC) machining was used to create the 500 mu m and 1000 mu m flow field channel dimensions in delrin. All of the plates were coated with gold to prevent corrosion and to improve conductivity. Two air-breathing 2.54 cm x 2.54 cm x 1.47 cm fuel cell stacks were designed and assembled for this research. The same membrane electrode assembly (MEA) with an active area of 1 cm(2) was tested with all of the silicon flow field plates with microchannels. The fuel cell performed well With the 20-mu m width and depth flow channels (maximum power density of 65 W cm(-2) or a maximum of 170 mA cm(-2) at 0.2 V), although all of the I-V tests yielded good results for room temperature, air-breathing fuel cells. Microchannels with widths and depths from 100 mu m to 20 mu m look promising for new high-current density microelectro mechanical (MEMS) fuel cell designs. (C) 2008 Elsevier B.V. All rights reserved.