In this work, a tin oxide film was prepared on a silicon wafer. It has exhibited the typical behaviour of a metal-oxide-semiconductor (MOS) structure. This MOS structure was stressed with 60Co-γ radiation in the total dose range of 0-500 kGy at room temperature. The effects of the 60Co gamma radiation on the following properties of Au/SnO2/n-Si (MOS) structures, have been determined before and after irradiation: dielectric constant (ε′), imaginary dielectric constant (ε″), dielectric loss tangent (tan δ) and AC conductivity (σAC). The values of ε′, ε″, tan δ and σAC show a strong dependence on the applied voltage and radiation dose. Additionally, the dielectric properties of MOS structures have been found to be strongly influenced by the presence of dominant radiation-induced defects. Experimental results show that the interfacial polarization contributes to the improvement of the dielectric properties of Au/SnO2/n-Si (MOS) structures. The capacitance and conductance measurements are corrected for series resistance before and after irradiation. © 2008 Elsevier B.V. All rights reserved.