The effects of Co-60 (gamma-ray) irradiation on the electrical and dielectric properties of Al-TiW-Pd2Si/n-Si Schottky diodes (SDs) have been investigated by using capacitance-voltage (C-V) and conductance -voltage (G/omega-V) measurements at room temperature and 500 KHz. The corrected capacitance and conductance values were obtained by eliminating the effect of series resistance (R-s) on the measured capacitance (C-m) and conductance (G(m)) values. The high-low frequency capacitance (CHF-CLF) method given in  as N-ss = (1/qA) [((1/C-LF) - (1/C-ox))(-1) - ((1/C-HF) - (1/C-ox))(-1)] was successfully adapted to the before-after irradiation capacitance given in this report as N-ss = (1/qA) [((1/C-bef) - (1/C-ox))(-1) - ((1/C-after) - (1/C-ox))(-1)] for the analyzing the density of interface states. The N-ss-V plots give a distinct peak corresponding to localized interface states regions at metal and semiconductor interface. The experimental values of the ac electrical conductivity (sigma(ac)), the real (M') and imaginary (M'') parts of the electrical modulus were found to be strong functions of radiation and applied bias voltage, especially in the depletion and accumulation regions. The changes in the dielectric properties in the depletion and accumulation regions stem especially from the restructuring and reordering of the charges at interface states and surface polarization whereas those in the accumulation region are caused by series resistance effect. (C) 2011 Elsevier B.V. All rights reserved.