NOVELTY - The fuel cell stack comprises an inlet gas manifold formed internally within gas flow field plates and characterized by a substantially triangular cross section, the largest side of the cross section adjoining the entry to the individual flow field plates; the apex portion opposite the largest side being curved instead of pointed; a small turning radius which is 0.5-2.0 times the equivalent diameter of the opening from the manifold into the individual flow field plates at the point of entry of the gas into the flow field plates; a fuel gas flow field plate, characterized by a gradual decrease in the cross section of each of the multiple passes of the flow passage in a finite number of steps, starting from the first pass, after the inlet, up to the last pass, before the outlet; a turning radius which is 1.5-9 times the equivalent diameter of the gas flow channels provided for each channel between passes; and an outlet manifold which is smaller than the inlet manifold; an oxidant flow field plate characterized by flow passages arranged such that the product water formed would either condense and drain smoothly towards the outlet manifolds or be carried by the flowing gas stream to the outlet; and by a turning radius at the entry point of gas into the flow field plate, which is about 0.5-2.0 times the equivalent diameter of the opening from the manifold into the individual flow field plates to reduce the pressure drop associated with the entry of the gas from the manifold into the flow field plate; and a coolant flow field plate characterized by several vertically and parallely disposed channels, each open at the top and the bottom; a horizontally disposed passage at the top, communicating with the open ends of each channel at the top; and a horizontally disposed passage at the bottom, communicating with the open ends of each channel at the bottom, the coolant inlet being in communication with the passage and the bottom and the coolant outlet being in communication with the passage at the top. Image 0/0