Core-shell perovskite-type oxides, with a relatively pure core and highly donor-doped shell, are widely investigated for, e.g., multilayer ceramic capacitors. Acceptor doped perovskite oxides are also widely investigated due to their applications as proton conductors. In the quest for new materials with novel properties we try to reverse both traits and form an inside-out core-shell structure with a highly donor-doped core and nominally undoped shell. A highly donor-doped core is expected to result in very few oxygen vacancies in this volume, due to self-compensation. The originally undoped shell, if thin enough, may behave as an acceptor doped area due to the migration of metal vacancies outwards. This may provide interesting properties resulting from internal electrical junctions and space charge. A possible synthesis route for the creation of such particles is the coating of previously synthesized nanoscaled donor-doped perovskite powder with undoped perovskite material. The synthesis route and the characterization of such inside-out core-shell (IOCS) nanopowder of Nb-doped BaCeO3 core and an undoped BaCeO3 shell are presented here. (C) 2010 Elsevier B.V. All rights reserved.