Portable hydrogen/oxygen fuel cell power sources were constructed using printed-circuit board (PCB) technology. Multiple iterations of miniature planar fuel cell devices were prototyped, demonstrating fast cycle innovation and dramatic power density improvements in < 1 year of development. Several novel flow structure and gas routing designs were explored. Electrical interconnections for configurable voltage were wired on board by printed-circuit traces and vias. Fuel cell device voltages ranging from 1 V single cells to 16 V planar arrays were demonstrated, with power output ranging from < 1 to >200 W. The lightweight laminate PCB technology allows the best prototypes to achieve >700 mW/cm(2) area power density and >400 mW/cm(3) volumetric power density. PCB technology offers an intriguing platform for portable fuel cell development below 1 kW. Possibilities for on board diagnostics/control and further power density improvements are envisioned. (C) 2003 Elsevier B.V. All rights reserved.