NOVELTY - Electrochemical cassette has at least one electrochemical cell with a membrane electrode assembly (MEA) (30, 32), and at least one reductant external manifold and oxidant external manifold. The cell further has a reductant flow field, an oxidant flow field and a bipolar plate (48). Each external manifold (80) has a primary manifold and at least one port (82) to be coupled to peripheral openings in the flow field to which the manifold is intended to deliver material.    USE - Used in fuel cell stack (claimed), particularly in proton exchange membrane (PEM) fuel cells. Useful in electrochemical applications and ion exchange applications.    ADVANTAGE - The majority of the cell component area is actively used in the cassette assembly with only a small portion used in sealing/manifolding the stack. At least 80 (preferably 85 - 95)% of the MEA cross-section is actively used for electrochemical reaction occurring within the stack. The cassette design simplifies the manufacture and assembly of its components. Continuously coated MEAs are readily used and compatible with roll-to-roll processing of MEAs. Encapsulation of all the components within the fuel stack provides a robust product. Component pieces of the stack are fabricated with very relaxed tolerances as sealing does not require gaskets and compression. Consequently reliability of seals is improved, electrical contact is improved and wider variety of resins can be used. The corrosion in the stack is reduced/prevented by segregating the reactant streams from end plates and collector plates of the stack. Problems associated with exposure of the MEA to non-aqueous coolants is reduced/prevented by segregating the coolant streams from the composite MEAs. Fuel cell stacks are fabricated by minimum of labor, reducing cost and allowing for process automation.    DETAILED DESCRIPTION - The primary manifold comprises a single conduit with substantially uniform cross-section along its length. The components of the cell are assembled and encapsulated about the periphery of the cassette by a sealant, which seals the junction between the ports and the peripheral openings.    DESCRIPTION OF DRAWING(S) - The figure shows an exploded view of a fuel cell with 3-cell fuel cell stack.    Fuel cell stack (10)    Membrane electrode assembly layers (30, 32)    Bipolar plate (48)    External manifold (80)    Ports. (82)