BiFeO3 and Bi0.90Ho0.10Fe0.95Sc0.05O3 compounds were prepared by using conventional solid state reaction method. X-ray diffraction patterns of both the compounds revealed that the compounds crystallized in R3c rhombohedral crystal structure whereas a minor orthorhombic phase was present in Bi0.90Ho0.10Fe0.95Sc0.05O3 compound along with R3c rhombohedral crystal structure. The temperature and frequency variation of impedance studies were conducted on both compounds. Measurements evidenced that grain resistance of BiFeO3 compound was improved with Ho and Sc co-substitutions. The temperature variation of ac conductivity data also corroborated the impedance data. The activation energies obtained from the temperature variation of grain resistances follow Arrhenius equations. The obtained activation energies clearly indicate that the co-substitution of Ho and Sc improved the insulating character of BiFeO3. The enhanced dielectric properties are also observed in the co-substituted BiFeO3 compound. © 2020 American Institute of Physics Inc.. All rights reserved.