A-site cation-disordered/ordered perovskite oxide LaBaCoO was synthesized by sol–gel method. Disordered LaBaCoO has higher conductivities than the ordered counterpart due to higher concentration of charge carriers, and is more stable at temperatures up to 850 °C and in argon, air and oxygen. Different conduction behavior in air/oxygen and argon suggests a p-type to n-type conduction transition caused by changes in chemical defects and charge compensation mode. Two conduction transitions associated with thermal-driven reduction of Co 4+ to Co 3+ and Co 3+ to Co 2+ were observed in air and oxygen. High conductivities and long-term structural stabilities suggested that LaBaCoO is a promising material as solid oxide fuel cell cathode or oxygen permeation membrane.