This study focuses on the fabrication and performance testing of unsupported platinum black electrodes for proton exchange membrane fuel cells. Experiments with platinum black coated diffusion media of varying anode and cathode catalyst loadings with H-2/air demonstrate successful performance and stability characteristics for anode catalyst loadings down to 0.25 mg/cm(2) while operating on pure H-2 and 0.62 mg/cm(2) cathode catalyst loadings, without significant voltage losses. The voltage losses as a result of reducing the platinum black cathode catalyst loadings from 2.6 to 0.62 mg/cm(2) are consistent with kinetic losses associated with the oxygen reduction reaction and lower electrocatalyst utilization. The study also highlights the durability and stability characteristics of these unsupported electrodes under extreme operating conditions. Optimization of the three-phase interface, namely electrode, electrolyte, and reactant gas, is shown to be dependent on the efficacy of the membrane-catalyst layer interface. (C) 2008 The Electrochemical Society.