All existing proton exchange membrane (PEM) fuel cell gas flow fields have been designed on the basis of single-phase gas flow distribution. The presence of liquid water in the flow causes non-uniform gas distribution, leading to poor cell performance. This paper demonstrates that a gas flow restrictor/distributor,as is commonly used in two-phase flow to stabilize multiphase transport lines and multiphase reactors,can improve the gas flow distribution by significantly reducing gas mal-distribution caused by either non-uniform water formation in parallel flow channels or flow instability associated with negative-slope pressure drop characteristic of two-phase horizontal flow systems.