Oxygen ion conduction behaviors of the 0-5 mol% excess Ba-doped La0.6Ba0.4InO3-delta cubic perovskite oxides have been investigated to elucidate their potential as electrolyte materials. The highest conductivity, 5.6 x 10(-2) S cm(-1) at 800 degrees C, is obtained at the 3 mol% excess Ba-doped composition benefiting from a supplementation of Ba2+ ions on the vacant A-site generated by the volatilization during the heat-treatment processes. Interestingly, all the samples except the undoped composition show curved electrical conductivity behavior in the Arrhenius plot. The activation energy is 0.50-0.52 eV in the high-temperature region above 900 degrees C, which is slightly lower than that of the doped LaGaO3 system. Moreover, all the samples show significantly lower activation energy values of both the high- and low-temperature regions compared with yttria-stabilized zirconia. The 3 mol% excess Ba-doped La1-xBaxInO3-delta (0.4 <= x <= 0.8) sample has also been studied. All of the compositions show a cubic perovskite structure and a nearly pure oxygen ion conduction behavior in a dry atmosphere even when p(O-2) = 1atm. The composition of x = 0.4 exhibits the highest oxygen ion conductivities. (C) 2014 Elsevier B.V. All rights reserved.