Cation-doped CeO2 electrolyte has been evaluated in single-cell and short-stack tests in solid oxide fuel cell environments and applications. These results, along with conductivity measurements, indicate that an ionic transference number of similar to0.75 can be expected at 800degreesC. Single cells have shown a power density >350 mW/cm(2). Multicell stacks have demonstrated a peak performance of >100 mW/cm(2) at 700degreesC using metallic separators.