Dielectric properties are studied as function of applied electric field frequency and composition for the series of ZnxCu1-xFe2O4 (x 0.30, 0.50, 0.70, 0.80 and 0.90) doped with controlled amounts of calcium chloride, prepared by standard ceramic technique. The compositions were characterized by X-ray diffraction (XRD) and IR absorption. XRD study shows formation of single-phase homogeneous compound with cubic structure. Dielectric constant (epsilon') and dielectric loss tangent (tandelta) are measured in the frequency range 100Hz-1 MHz, at room temperature and they show dispersion with increase infrequency. This is attributed to the interfacial polarization. The a.c. resistivity (rho(a.c).) is calculated from dielectric constant (epsilon') and dielectric loss tangent (tandelta). From the compositional study, it was found that the dielectric constant (epsilon') shows decreasing trend with increasing both zinc concentration as well as doping percentage of calcium chloride. The conduction mechanism in these ferrites is discussed on the basis of electron exchange between Fe2+ and Fe3+ ions on the octahedral B-sites. (C) 2003 Elsevier Science B.V All rights reserved.