Dielectric properties and ac electrical conductivity of the Al/SiO2/p-Si (MIS) Schottky diodes were studied in the frequency and temperature range of 10 kHz-1 MHz and 300-400 K, respectively. Experimental results show that the dielectric constant (epsilon'), dielectric loss (epsilon ''), loss tangent (tan delta), ac electrical conductivity (sigma(ac)) and the electric modulus were found a strong function of frequency and temperature. The values of the epsilon', epsilon '' and tan delta decrease with increasing frequencies due to the interface states capacitance and a decrease in conductance with increasing frequency. Also, these values increase with increasing temperature. The sigma(ac) is found to increase with increasing frequency and increasing temperature. The variation of conductivity as a function of temperature and frequency reveals non-adiabatic hopping of charge carriers between impurities localized states. In addition, the experimental dielectric data have been analyzed by considering electric modulus formalism. (C) 2008 Elsevier B.V. All rights reserved.