Disclosed is a novel fluid flow field plate for use in a solid polymer electrolyte fuel cell. The flow field plate is made of a suitable electrically conducting material and comprises a substantially planar surface, a flow field formed in said substantially planar surface, said flow field comprising a plurality of staggered lands defining a network of substantially symmetric interconnected orifices and diagonal channels in the flow field and a fluid supply manifold through which fuel and an oxidant are introduced to the flow field and a fluid exhaust manifold through which reaction by-products and excess fuel and oxidant are removed from the flow field. Streams of the fuel, oxidant and reaction by-products are continually separated and diverted into separate channels, and the separated streams are then mixed with streams from adjacent channels in the orfices.