In this work, we investigated electrical conduction properties of SmBO3-based materials with the high temperature phase, in which Sm was substituted partially by Ca or Sr. From conductivity measurements at 500-925 degrees C, it was found that conductivities of the substituted SmBO3 were much higher than an unsubstituted one, and were 2.9 x 1.0(-6) - 1.8 x 10(-4) S . cm(-1) under moisturized conditions at the temperature range. H/D isotope effects on conductivity demonstrated protonic conduction in the substituted specimens. Protonic conduction at elevated temperature was also confirmed by electromotive force measurements of concentration cells using the Sr-substituted SmBO3 as the electrolyte although there was a slight contribution of electronic conduction. (C) 2015 Elsevier B.V. All rights reserved.