The flow distribution obtained with three different bipolar plate geometries has been studied, analyzing their fluid dynamic performance. Three plate topologies have been selected in some way representative of different design models commonly used. The configurations tested are a set of parallel diagonal channels, a branching cascade type, and a serpentine distribution of parallel channel blocks. The flow distribution across the plates has been first simulated numerically. To visualize the flow pattern at the plate channels plane, a laser-induced fluorescence (LIF) trace tracking technique has been applied. From experimental and numerical simulations it is concluded that the diagonal topology distributes the flow in a non-uniform way. On the other hand, an inadequately large pressure drop is established along the serpentine-parallel plate. In the cascade case, both velocity and pressure fields are very uniform, and it can be expected to produce a very homogeneous distribution of reactants over the catalyst layer. (C) 2007 Elsevier B.V. All rights reserved.