The electronic structure of the protonic conductor Y-doped BaCeO3 (BaCe0.90Y0.10O3-delta) has been studied by soft-X-ray spectroscopy. The valence band of H-2-annealed BaCe0.90Y0.10O3-delta, which consists of the 0 2p states hybridized with Ce 4f states, shifts to the higher binding energy side by approximately 0.4 eV. In the air-annealed BaCe0.90Y0.10O3-delta, holes and acceptor levels are observed at the top of the valence band and just above E-F, respectively. Their intensities are lower in H-2-annealed BaCe0.90Y0.10O3-delta. These findings indicate directly that hydrogen doping compensates for the presence of the holes. (c) 2005 Elsevier B.V. All rights reserved.