The purpose of this paper is to investigate frequency-dependent electrical characteristics of the interface states in Sn/p-Si metal semiconductor (MS) Schottky structures. To yield quantitative information about their frequency (f) and voltage (V) dependent characteristics, Sn/p-Si MS structures have been studied by using capacitance (C) and conductance (G/omega) measurements over a wide range of frequencies (50 kHz-1 MHz). The increase in capacitance at lower frequencies is seen as a signature of interface states, and the densities of which are evaluated to be of the order of congruent to 10(10) cm(-2) eV(-1). The presence of the interfaces states (N(ss)) is also evidenced as a peak in the capacitance-frequency characteristics that increases in magnitude with decreasing frequencies. Furthermore, the voltage and frequency dependence of series resistance (R(s)) were calculated from the C-V and G/omega-V measurements and plotted as functions of voltage and frequency. The effect of R(s) on C and G/omega is found noticeable at high frequencies. The C-V-f and G/omega-V-f characteristics of studied structures show fairly large frequency dispersion especially at low frequencies due to N(ss) in equilibrium with the semiconductor. The experimental values of interface state densities and series resistance from C-V-f and G/omega-V-f measurements were obtained in the ranges of 3.46 x 10(10)-1.26 x 10(9) cm(-2) eV(-1) and 71.1-57.3 Omega, respectively. Experimental results show that both the rs and N(ss) values should be taken into account in determining frequency-dependent electrical characteristics. (C) 2009 Elsevier Ltd. All rights reserved.