NOVELTY - A corrosion-resistant electrochemical device comprises individual fuel cells, bipolar plate(s), and neutralization agent or ion exchange media. Each fuel cell has a membrane-electrode assembly comprising anode catalyst layer, anode diffusion layer, cathode catalyst layer, and cathode diffusion layer. The neutralization agent or ion exchange media is sufficient to neutralize corrosive species in fuel cell effluent in situ.    USE - For use as proton exchange membrane fuel cells useful in converting chemical potential energy into electricity and heat.    ADVANTAGE - The inventive device has increased power densities and operating lifetimes, and reduced manufacturing and production costs. It is lightweight, compact, low cost, and non-corroding. It enables the use of low cost plate materials and coatings without sacrificing performance and durability. It eliminates the need for sensitive coating processes that can result in pores and failed plates and cells. The neutralized cell effluent can be recirculated without requiring additional components in the system.    DETAILED DESCRIPTION - A corrosion-resistant electrochemical device comprises individual fuel cells connected in electrical series, bipolar plate(s) (14) disposed between adjacent individual fuel cells, and a neutralization agent or ion exchange media disposed within the electrochemical device. Each fuel cell has a membrane-electrode assembly (12) comprising anode catalyst layer (22) and anode diffusion layer (20) disposed on one side of an electrolyte membrane (24) and a cathode catalyst layer (26) and cathode diffusion layer (28) disposed on an opposite side of the electrolyte membrane. The bipolar plate has oxygen flow channels (16) and hydrogen flow channels (18). The neutralization agent or ion exchange media is sufficient to neutralize corrosive species in fuel cell effluent in situ. An INDEPENDENT CLAIM is also included for a method for operating a corrosion-resistant electrochemical device comprising providing individual fuel cells connected in electrical series, disposing at least one bipolar plate between adjacent individual fuel cells, disposing a neutralization agent or ion exchange media within the electrochemical device, and operating the electrochemical device.    DESCRIPTION OF DRAWING(S) - The drawing shows a partially exploded schematic depiction of PEM fuel cell stack repeating unit employing in situ neutralization.    Membrane electrode assembly (12)    Bipolar plate (14)    Oxygen flow channels (16)    Hydrogen flow channel (18)    Anode diffusion layer (20)    Catalyst layer (22)    Electrolyte membrane (24)    Cathode catalyst layer (26)    Cathode diffusion layer (28)