The proton transport properties of La0.9M0.1YbO3-delta (M = Ba, Sr, Ca, Mg) were studied by the electrical conductivity measurement technique in the temperature range of 673-1173 K. The proton concentration was estimated by the weight changes due to the hydration reaction. The electrical conductivity and proton concentration of La0.9Ba0.1YbO3-delta were the highest in La0.9M0.1YbO3-delta. The electromotive force of a hydrogen gas concentration cell using La0.9Ba0.1YbO3-delta as the electrolyte was observed at 673-1073 K, and was in a good agreement with the theoretical values assuming that the proton transport number was unity. (c) 2013 Elsevier Ltd. All rights reserved.