CuFe2O4 and Cu1-xZnxGa0.3Fe1.7O4 with (0.0 <= x <= 0.5) are synthesized. Crystallographic phase transformation from tetragonal-to-cubic is occurred at x = 0.1. Dielectric permittivities (epsilon' and epsilon") and dielectric loss tangent (tan delta) are studied for the prepared samples from room temperature up to 700 K in the frequency range (10(2)-10(5) Hz). The relation of tan delta with frequency at different temperatures shows relaxation spectra where the relaxation time and the maximum frequency of the hopping process are determined. Dielectric anomaly at the transition temperature T-c is pronounced in the relation of dielectric permittivity with temperature. The determined T-c is found to decrease linearly with increasing Zn concentration. The variation of (epsilon', epsilon" and tan delta) with frequency and temperature displayed a strong dependence on both of gallium and zinc concentrations. Obtained results are explained based on the cation-anion-cation and cation-cation interactions over the octahedral site in the spinel structure. (c) 2005 Elsevier B.V. All rights reserved.