A solid polymer electrolyte fuel cell comprising: a membrane electrode assembly comprising a solid polymer electrolyte and an anode and a cathode on opposite sides of the solid polymer electrolyte; an anode gas diffusion layer for a fuel adjacent the anode; a cathode gas diffusion layer for an oxidant adjacent the cathode; a reactant flow field plate for a reactant selected from the group consisting of the fuel and the oxidant, the reactant flow field plate comprising a reactant flow field adjacent the gas diffusion layer for the reactant wherein the reactant flow field comprises a plurality of reactant flow field channels fluidly connected to an inlet plenum channel at an inlet end of the reactant flow field and to an outlet plenum channel at an outlet end of the reactant flow field wherein the outlet plenum channel is transverse to the plurality of reactant flow field channels; a reactant inlet in the reactant flow field plate near the inlet end of the reactant flow field and fluidly connected to the inlet plenum channel; a reactant outlet in the reactant flow field plate near the outlet end of the reactant flow field and to the side of the plurality of reactant flow field channels; a reactant backfeed slot on the side of the reactant flow field plate opposite the gas diffusion layer for the reactant and fluidly connected to the reactant outlet; and a reactant backfeed port in the reactant flow field plate fluidly connecting the reactant backfeed slot to the outlet plenum channel; a landing in the reactant flow field plate and adjacent the gas diffusion layer for the reactant wherein the landing is transverse to the plurality of reactant flow field channels and located on the side of the outlet plenum channel opposite the plurality of reactant flow field channels; a relief plenum channel in the reactant flow field plate and adjacent the gas diffusion layer for the reactant wherein the relief plenum channel is transverse to the plurality of reactant flow field channels and located on the side of the landing opposite the outlet plenum channel; a relief backfeed slot on the side of the reactant flow field plate opposite the gas diffusion layer for the reactant and fluidly connected to the reactant outlet; and a relief backfeed port in the reactant flow field plate fluidly connecting the relief backfeed slot to the relief plenum channel, characterized in that the gas diffusion layer for the reactant fluidly connects the outlet plenum channel to the relief plenum channel. a membrane electrode assembly comprising a solid polymer electrolyte and an anode and a cathode on opposite sides of the solid polymer electrolyte; an anode gas diffusion layer for a fuel adjacent the anode; a cathode gas diffusion layer for an oxidant adjacent the cathode; a reactant flow field plate for a reactant selected from the group consisting of the fuel and the oxidant, the reactant flow field plate comprising a reactant flow field adjacent the gas diffusion layer for the reactant wherein the reactant flow field comprises a plurality of reactant flow field channels fluidly connected to an inlet plenum channel at an inlet end of the reactant flow field and to an outlet plenum channel at an outlet end of the reactant flow field wherein the outlet plenum channel is transverse to the plurality of reactant flow field channels; a reactant inlet in the reactant flow field plate near the inlet end of the reactant flow field and fluidly connected to the inlet plenum channel; a reactant outlet in the reactant flow field plate near the outlet end of the reactant flow field and to the side of the plurality of reactant flow field channels; a reactant backfeed slot on the side of the reactant flow field plate opposite the gas diffusion layer for the reactant and fluidly connected to the reactant outlet; and a reactant backfeed port in the reactant flow field plate fluidly connecting the reactant backfeed slot to the outlet plenum channel; a landing in the reactant flow field plate and adjacent the gas diffusion layer for the reactant wherein the landing is transverse to the plurality of reactant flow field channels and located on the side of the outlet plenum channel opposite the plurality of reactant flow field channels; a relief plenum channel in the reactant flow field plate and adjacent the gas diffusion layer for the reactant wherein the relief plenum channel is transverse to the plurality of reactant flow field channels and located on the side of the landing opposite the outlet plenum channel; a relief backfeed slot on the side of the reactant flow field plate opposite the gas diffusion layer for the reactant and fluidly connected to the reactant outlet; and a relief backfeed port in the reactant flow field plate fluidly connecting the relief backfeed slot to the relief plenum channel,