In this paper, we present a detailed investigation of the electrical and dielectric properties of the Au/SnO2/ n-Si (MIS) structures. The capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics have been measured in the frequency range of 1 kHz-1 MHz at room temperature. Calculation of the dielectric constant (epsilon'), dielectric loss (epsilon"), loss tangent (tan delta), ac electrical conductivity (sigma(ac)), ac resistivity (p,c) and the electric modulus are given in the studied frequency ranges. Experimental results show that the values of dielectric parameters are a strong function of frequency. The decrease of epsilon' and epsilon" with increasing frequency were observed. In addition the increase of c,c with increasing frequency is founded. Also, electric modulus formalism has been analyzed to obtain the experimental dielectric data. The interfacial polarization can be more easily occurred at the lower frequency and/or with the number of interface state density between SnO2/Si interface, consequently, contribute to the improvement of dielectric properties of MIS structure. (C) 2008 Elsevier B.V. All rights reserved.