We have synthesized the perovskite oxides of the (Ba0.3Sr0.2La0.5)(In1-xFex)O3-delta System and measured the total electrical conductivity as a function of temperature and oxygen partial pressure. It was found that the single-phase composition region extended from x = 0.0 to x = 1.0, and that the Fe valence increased from 3.06 to 3.50 in that region. The electrical conductivity was semiconducting from x = 0.0 to x = 0.40 and metallic from x = 0.50 to x = 1.0. The total electrical conductivity at 800 degrees C also increased with the Fe content and achieved a maximum value of 140 (S/cm) at x = 1.0. From the dependence of the electrical conductivity on the oxygen partial pressure, we conclude that above x = 0.50, the majority carriers are holes. The estimated hole conductivity increased exponentially with the amount of Fe4+ cation present. The oxide ion conductivity was dependent on the oxygen vacancy content. (c) 2006 Elsevier B.V All rights reserved.