NOVELTY - An electrochemical cassette comprises at least one membrane electrode assembly adapted for contact with at least two plates, each plate comprising flow field(s), where each of which comprises groove(s). The flow fields comprise an oxidant flow field, a fuel flow field, or a coolant flow field. Each membrane electrode assembly and each plate comprise oxidant manifold opening(s) and fuel manifold opening(s).    USE - As a fuel cell cassette (claimed) useful in a variety of electrochemical applications, particularly fuel cell applications.    ADVANTAGE - The electrochemical cassette is less complex, more reliable and less costly to manufacture. It minimizes or prevents exposure of the membrane electrode assembly to the reactants, waste streams or cooling fluids around the various manifolds avoiding cross-cell potential problems or material incompatibility associated with the exposure. It can be formed into a fuel stack at reduced injection pressures to simplify component design and which do not require a significantly large area of each layer to be sacrificed to accommodate the sealing process.    DETAILED DESCRIPTION - An electrochemical cassette comprises at least one membrane electrode assembly adapted for contact with at least two plates (20), each plate comprising flow field(s), where each of which comprises groove(s) (23). The flow fields comprise an oxidant flow field, a fuel flow field, or a coolant flow field. Each membrane electrode assembly and each plate comprise oxidant manifold opening(s) and fuel manifold opening(s) where each respective manifold opening extends through the thickness of the cassette. Each plate has sealant channel(s) that extends through at least a portion of the thickness. One or more membrane electrode assemblies and plates are assembled and encapsulated about the periphery by a sealant. The sealant contemporaneously seals the respective channels of the plate(s) to selectively block those reactant manifold openings that are not intended to deliver material to a particular flow field.    An INDEPENDENT CLAIM is included for a fuel cell stack, comprising electrochemical cassette(s) as above and two end plates having opening(s) that align with the reactant manifold opening(s). The end plates are assembled on the top and bottom of the stack of electrochemical cassette(s) such that the openings in the end plates align with the fuel manifold openings, the oxidant openings, and optionally the coolant manifold openings.    DESCRIPTION OF DRAWING(S) - The figure shows a top view of the fuel flow field face of a bipolar plate.    Fuel ports (15)    Coolant (17)    Oxidant (19)    Plates (20)    Groove (23)