Recent investigations into the mixed conducting properties of both copper- and gadolinium-doped barium cerates result in an interesting phase, identified as BaCuGd2O5, which exhibits substantially higher conductivity than any of the doped-barium cerate compounds studied. The predominant portion of the conduction, however, is electronic. Further, composites consisting of BaCuGd2O5 and BaCe0.8Gd0.2O3 phases are studied as electrodes for barium cerate-based electrolytes. The composites are shown to have an ionic transference number of about 0.2. As electrodes, the composite material has shown excellent ambipolar transport properties and catalytic activities with interfacial resistances reduced by more than one order of magnitude compared to silver electrodes.