A recirculating reagent fuel-cell includes an ion-exchange membrane interposed between an anode and cathode anode to form a membrane/electrode assembly (MEA), the MEA interposed between a fuel gas diffusion layer and an oxidant gas diffusion layer. An oxidant and fuel flow network are provided having an input portion for supplying reagent and an output portion for removing reagent after electrochemical reaction. At least one of the oxidant flow network and fuel flow network includes a recirculation loop, the recirculation loop feeding back a portion of the fuel or oxidant after electrochemical reaction to their respective input portion. The fuel flow network can include a water vapor condenser to extract water from the cathodes in proportion to the external load on the fuel cell stack and the fuel flow network can include an evaporator, where water is fed to the evaporator in the fuel loop from the condenser in the oxidant feed loop.