Abstract: The invention provides a metal-supported solid electrolyte electrochemical cell, multi cell reactor assemblies incorporating a plurality of such cells, and processes of forming the electrochemical cells. In one embodiment, the electrochemical cell includes a central electrolyte membrane, first and second perforated metallic layers adhered to each of the major surfaces of the central electrolyte membrane, and first and second outer, non-porous electrolyte layers formed above the metallic layers. In another embodiment, first and second inner, porous electrolyte layers are sandwiched on either side of the central membrane, between the first and second metallic layers. The electrochemical cell is thus generally formed from ceramic material as thin layers supported on non-porous, robust metallic layers, designed to behave as though made of metal. Preferably, the electrochemical cell includes metallurgically bonded electrical interconnects and/or gas seals.