The influence of indium content on the electrical conduction behavior of Sm- and In-co-doped BaCe0.80-xSm0.20InxO3-delta proton conductor was investigated by impedance spectroscopy. The structural characteristics were studied by means of X-ray diffraction, Raman spectra, high resolution transmission electron microscopy, and thermogravimetric analysis. Both long and short range structural symmetry increased within content, from orthorhombic (x = 0-0.50) to cubic structure (x = 0.60-0.80). No oxygen vacancy ordering or microdomains were detected. The proton concentration of the hydrated samples BaCe0.80-xSm0.20InxO3-delta (x = 0-0.20) decreased with In level. The electrical conductivity of the co-doped samples decreased with In content in wet 5% H-2/Ar and wet Ar atmospheres. The reasons for the decreased electrical conductivity were discussed. The variation of electrical conductivity of BaCe0.80-xSm0.20InxO3-delta with In concentration can be applicable to other RE- and In-co-doped BaCeO3 materials. (C) 2011 Elsevier B.V. All rights reserved.