DC conductivity and dielectric studies of CoxZn1−xFe2O4 (x = 0.32, 0.49, 0.79), BaFe12O19, and Mg0.25Zn0.75Fe2O4 are reported as a function of temperature and frequency. The lattice constant and the existence of a single phase are established from X‐ray studies. The dielectric behaviour is attributed to the Maxwell‐Wagner polarisation. A dispersion region is observed in one of the cobalt‐zinc ferrites and the barium ferrite. Activation energies are calculated for these two ferrites from dielectric measurements. The conductivity of these ferrites is explained by the hopping mechanism. Activation energies and the transition temperatures are presented. Copyright © 1980 WILEY‐VCH Verlag GmbH & Co. KGaA