Solid oxide fuel cells

A solid oxide fuel cell for high temperature operation, said fuel cell comprising:

• a refractory solid electrolyte,
• an anode and a cathode both in intimate contact with the electrolyte;
• and
• an electronically conducting interconnect medium having pores or channels therethrough permitting oxidant and fuel to be delivered without mixing respectively to the cathode and the anode, wherein the anode, cathode and interconnect medium provided as zones and are comprised of a single common unitary material whose composition varies through the material to provide zones and interconnect medium, the anode and cathode being present as zones adjacent to different surfaces of the material and the interconnect medium being present as a zone intermediate to the cathode and anode zones.