Single phase BaCe0.8Pr0.2O3-delta perovkite was obtained by the modified Pechini method followed by self-combustion and sintering at 1350 degrees C. Crystal structure, thermodynamic stability, linear expansion and electrical properties were characterized as a function of temperature, under oxidizing and reducing atmospheres. BaCe0.8Pr0.2O3-delta presents phase transitions under both atmospheres, which do not compromise the transport properties. The electrical conductivity showed a mixed character, dominated by electronic and oxygen vacancies transport in O-2-containing atmosphere. Pr+4 reduction was observed above 400 degrees C under H-2-containing atmosphere. This reduction increases the oxygen non-stoichiometry and OH center dot charge carriers concentration, unit cell volume and thermal expansion coefficients (TECs). Pr+4 reduction suppresses the electronic conduction and hence the transport number for OH center dot would be dominant in wet reducing atmosphere. (C) 2016 The Electrochemical Society. All rights reserved.