Fuel cell with cooling system based on direct injection of liquid water

A stack of polymeric membrane fuel cells fed with gaseous reactants wherein said membrane separates an anodic compartment from a cathodic compartment comprising bipolar plates, gaskets optionally provided with channels for feeding and discharging fluids, porous electrodes, catalytic layers interposed between the membranes and the electrodes, manifolds for feeding the flow of reactants, manifolds for the discharge of the unconverted portions of the reactants, of the inerts and of the produced water, and at least an injection point connecting a hydraulic circuit wherein a water flow is provided inside at least one compartment of the cells, said water flow provides contemporaneously for the humidification of the membranes and for the removal of the generated heat, characterised in that at least one compartment of the cells fed with the reactants and water coming from the injection point comprises an electrically and thermally conductive reticulated element interposed between the electrodes and the bipolar plates, which distributes said water flow through the whole volume occupied by the gaseous reactants.