The dielectric characteristics of gamma irradiated Au/SnO2/n-Si/Au (MOS) capacitor were studied. The MOS capacitor was irradiated by a Co-60 gamma radiation source with a dose rate of 0.69 kGy/h. The dielectric parameters such as dielectric constant (epsilon'), dielectric loss (epsilon ''), loss factor (tan delta) and ac electrical conductivity (sigma(ac)) were calculated from the capacitance-voltage (C-V) and conductance-voltage (G/omega-V) measurements. It is found that the C and G/omega values decrease with the increasing total dose due to the irradiation-induced defects at the interface. Also, the calculated values of epsilon', epsilon '' and sigma(ac) are found to decrease with an increased radiation dose. This result indicates that the dielectric characteristics of the MOS capacitor are sensitive to gamma-ray dose. (C) 2014 Elsevier Ltd. All rights reserved.