For the mixed perovskite oxide system (Sr0.8125La0.1875) (Zr0.75FexRu0.25−x)O3−&dgr;, electrical conductivities were measured in air as a function of temperature and Ru/Fe ratio. Liquidus and solidus temperatures were determined in air by the laser melting point measurement technique. The substitution of Ru for Fe was found to increase the electrical conductivity by over an order of magnitude while decreasing the solidus temperature of the Fe‐rich solid solution by less than 10%.