To show the effect of gamma radiation, Au/ Polyvinyl Alcohol (Co, Zn-doped)/n-Si Schottky barrier diodes (SBDs) were exposed to 60 Co c-ray source at room temperature. These structures were investigated by using current-voltage (I-V), capacitance-voltage (C-V), and conductance-voltage (G/x-V) measurement methods before and after irradiation. The C-V and G/x-V measurements were carried out at 1 MHz. The density of interface states (N ss ) as a function of E c -E ss was obtained from the forward bias I-V data by taking into account the bias dependence effective barrier height (U e ) and series resistance (R s ) of device at room temperature. Experimental results show that the values of ideality factor (n), R s , and N ss increased after gamma irradiation. It was found to degrade the reverse leakage current with radiation whereas its effect on the forward I-V characteristics was negligible. The results show that main effect of the radiation is the generation of N ss with energy level within the forbidden band gap of Si between polymer and semiconductor. In addition, the values of R s were determined from Cheung's method, and it was seen that these values increased with radiation effect. As seen I-V and C-V characteristics, the main electrical parameters such as ideality factor (n), R s , N ss were strongly influenced with the presence of radiation.