In the continuing progress of fuel cell technology, CeO 2 double doped electrolytes appears to be promising for lowering the SOFC's working temperatures. Ceria electrolytes have better ionic conductivities than YSZ but, at low oxygen partial pressures, the chemical reduction of ceria leads to increasing electronic conduction. Double doping of the ceria increases the electrolytic conduction range without changing its conductivity. To avoid stress development within the ceria crystallographic structure, the dopants mix must have a mean ionic radius as close as possible to the critical ionic radius. Ceria electrolytes with various compositions and dopant concentrations are synthesized with a combinatorial chemistry approach. To synthesize new electrolytes, solution plasma spraying with nitrate salt precursor is used. The reaction is completed and nanocrystalline thin layers of ceramic are formed in the plasma. Comparative studies of plasma spraying techniques, with YSZ powder plasma spraying as electrolyte reference, were performed. Also, comparative impedance spectroscopy measurements are to be performed to validate the double doping hypothesis and thence to identify the best electrolytes in the suite of over 300 new materials.