The total electrical conductivity of A(3+)B(3+)O(3)-type perovskites (La1-xSrx)ScO3-delta (x=0.1 and 0.2) was investigated under controlled atmospheres between 573 and 1273 K. In the presence of water vapor and/or hydrogen, the perovskites showed predominantly proton conduction below 873 and 973 K for x=0.1 and 0.2, respectively. The x=0.2 compound showed the higher proton conductivity of ca. 6x10(-3) S cm(-1) at 873 K. The x=0.1 and 0.2 materials showed apparent activation energy for proton conduction between 573 and 723 K of 0.54 and 0.55 eV. The higher proton conductivity of the x=0.2 perovskite is presumed to arise from a higher mobile proton concentration than that of the x=0.1 compound. (C) 2004 Elsevier B.V. All rights reserved.