NOVELTY - A fuel cell assembly comprises fuel cell stack (200). The fuel cell stack comprises fuel cells having two electrodes (11, 12) that are spaced to form an electrolyte chamber (208), a first gas chamber for a first gas on the opposite side of a first electrode from the electrolyte chamber, and a second gas chamber for a second gas on the opposite side of the electrode from the electrolyte chamber. The electrode incorporates a catalyst. The fuel cell stack incorporates electrolyte chamber frames to define the electrolyte chambers and electrolyte chamber frames to define the gas chambers.    USE - For batteries.    ADVANTAGE - The assembly allows the electrodes to be replaced while allowing reuse of the other parts of the stack and allowing the electrodes to be installed in one orientation, thus eliminating the possibility of installing new electrodes in an incorrect orientation when old electrodes are replaced.    DETAILED DESCRIPTION - A fuel cell assembly comprises fuel cell stack; a releasable clamp to retain components of fuel cell stack; and casing (240) into which the fuel cell stack insertable. The fuel cell stack comprises fuel cells having two electrodes that are spaced to form an electrolyte chamber, a first gas chamber for a first gas on the opposite side of a first electrode from the electrolyte chamber, and a second gas chamber for a second gas on the opposite side of the electrode from the electrolyte chamber. The electrode incorporates a catalyst. The fuel cell stack incorporates electrolyte chamber frames to define the electrolyte chambers and electrolyte chamber frames to define the gas chambers. The electrodes are secured between the electrolyte chamber frames and the gas chamber frames. At least one of end plate (206) defines ports to supply or withdraw fluids from the fuel cells. The casing provides compression mechanism to compress the fuel cell stack components together.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of components forming a cell stack.    Electrodes (11, 12)    Cell stack (200)    Plate (206)    Electrolyte chamber (208)    Casing (240)