Epitaxial heterostructures consisting of an yttrium doped barium cerate, BaCe0.8Y0.2O3,(BCY) layer sandwiched between two yttrium doped barium zirconate, BaZr0.8Y0.2O3,(BZY) thin layers have been deposited on insulating (001) MgO substrates by pulsed laser deposition. The first BZY layer was aimed at improving the lattice match with the MgO substrate, the second at protecting the BCY layer. Ionic conductivity has been studied in the 300 degrees C-600 degrees C temperature range as a function of the BCY thickness in dry air and wet 5% H-2 in Ar atmosphere. In both atmospheres, heterostructures showed a conductivity slightly larger than that of BCY pellets sintered under optimized conditions. Such a result has been attributed to the absence of blocking grain boundaries in the epitaxial heterostructures due to their good crystallographic quality. The BCY sandwich heterostructures showed an improved chemical stability relative to standard BCY pellets. (C) 2014 Elsevier B.V. All rights reserved.