A design configuration is presented for integrated series connection of polymer electrolyte fuel cells in a planar array. The design is particularly favorable for miniature fuel cells and has been prototyped using a variety of etch and deposition techniques adopted from microfabrication. The series path is oriented in a ''flip-flop" configuration, presenting the unique advantage of a fully continuous electrolyte requiring absolutely no interconnecting bridges across or around the membrane. Electrical interconnections are made by thin-film metal layers that coat etched flow channels patterned on an insulating substrate. Both two-cell and four-cell prototype, have successfully demonstrated the expected additive performance of the integrated series, and peak power in a four-cell silicon assembly with hydrogen and oxygen has exceeded 40 mW/cm(2). Factorial experimentation has been applied to investigate the adequacy of metal film conduction over etched topology, and results conclude that film thickness dominates over other design parameters. The design effort and subsequent testing has uncovered new topics for extended study, including the possibility of lateral ionic conduction within the membrane us well as the effects of non-uniform reactant distribution.