An improved proton exchange membrane fuel cell assembly and fuel cell stack assembly are provided for the economical and efficient production of electricity. The present invention comprises improved flow fields, which provide improved and more efficient mass transport of the reactants in the fuel cell and the fuel cell stack assembly. The improved flow fields comprise three-dimensional open-cell foamed metals that are preferably plated with gold. The improved reactant supply system comprises an improved distribution frame to house fuel cells wherein the reactants are directly connected to the improved flow fields.