In this research, we investigated the effect of Co-60 gamma-ray exposure on the electrical properties of Au/SnO2/n-Si (MIS) structures using current-voltage (I-V) measurements. The fabricated devices were exposed to gamma-ray doses ranging from 0 to 300 kGy at a dose rate of 2.12 kGy h(-1) in water at room temperature. The density of interface states N-ss as a function of E-c-E-ss is deduced from the forward bias I-V data for each dose by taking into account the bias dependence effective barrier height and series resistance of device at room temperature. Experimental results show that the gamma-irradiation gives rise to an increase in the zero bias barrier height Phi(BO), as the ideality factor n and N-ss decrease with increasing radiation dose. In addition, the values of series resistance were determined using Cheung's method. The R-s increases with increasing radiation dose. The results show that the main effect of the radiation is the generation of interface states with energy level within the forbidden band gap at the insulator/semiconductor interface. (C) 2007 Elsevier B.V. All rights reserved.