The aim of this study is to investigate structure and electrical response of mixed di-tri valent cation containing Ce1-xHo0.1SrxO2-delta (x = 0.02-0.1) ionic conductor. The Rietveld analysis of X-ray diffraction profiles confirms the solubility limit of Sr2+ ions into ceria lattice upto x = 0.06 and the co-existence of secondary phase SrCeO3 afterwards. With the increase of Sr2+ ions into ceria, formation of defect cluster increases and concentration of free oxygen vacancies decreases. The composition x = 0.06 shows lowest conductivity due the highest association energy of defect clusters. The dielectric constant plays a crucial role for the formation of defect clusters and conductivities of the compositions. The presence of SrCeO3 and depletion of oxygen vacancies at grain boundary region enhance the grain boundary resistances. The dielectric constant of grain boundary region affects the grain boundary conductivity. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.