The electronic structure in the bulk state of protonic conductor In-doped CaZrO3 (CZI) has been investigated by soft-X-ray emission spectroscopy (SXES). Comparing with the SXES spectrum of dried CZI, the Fermi level (E-F) of proton-doped CZI is shifted to the conduction band side by about 1.0 eV The SXES spectrum of proton-doped CZI has two features, which correspond to the hole state at the top of the valence band and the proton-induced level near E-F. These results indicate that the doped proton acts as a positive charge in the bulk state. (C) 2003 Elsevier B.V All rights reserved.