The dielectric constant epsilon' and the electrical conductivity (sigma) for Mg1+xTixEryFe2-2x-yO4; 0.1 less than or equal to x less than or equal to 0.9 doped with a constant rare earth ions, y = 0.025 were measured in the temperature range, 350-750 K. The measurements were carried out as a function of frequency, 50-1000 kHz. X-ray diffractograms show that, the investigated samples reveal spinel structure. From the obtained data, it was found that the effective number of ferrous ions on octahedral sites which was available for the electric polarization as well as electrical conductivity decreases with increasing Ti concentration. The effect of gamma-irradiation on both structural and electrical properties was also studied. The ratio Fe2+/Fe3+ plays a dominant role in the decrease of the crystal size due to irradiation damage with gamma-rays. (C) 2003 Elsevier Science B.V. All rights reserved.