A molded multi-part flow field structure includes a molded flow field plate formed of a conductive material comprising a first polymer. A molded frame is disposed around the flow field plate and formed of a non-conductive material comprising a second polymer. The molded flow field plate and frame preferably define a unipolar flow field structure. Manifolds are formed in the molded frame, and a molded gasket arrangement is disposed proximate a periphery of the manifolds. A molded coupling arrangement may be formed to extend from the frame and configured to couple the flow field structure with other unipolar flow field structures to define a continuous web of the unipolar flow field structures.