Electrochemical oxygen pumping was employed to study oxygen transport characteristics of electrolytes and electrodes. Oxygen transference numbers were measured by measuring volume changes using a liquid column in a capillary. The two electrolytes used were 10 mol% Ca doped CeO2 and 20 mol% Sr doped Bi2O3. The electrodes used were Pt, Pd/Au, La0.7Sr0.3MnO3-delta, La0.5Sr0.5MnO3-delta, and La0.7Sr0.3FeO3-delta. The manganite perovskite electrode performance was comparable to Pt at 700-degrees-C on both electrolytes. The bismuth electrolyte was found to be reduced to metal on the cathode side at high current densities.