In this paper, the frequency and voltage dependence of the electrical and dielectric properties of metal-insulator-semiconductor (MIS) Schottky diodes has been investigated using capacitance-voltage (C-V) and conductance-voltage (G/omega-V) characteristics in the frequency range of 1 kHz-1 MHz at room temperature. Calculations of the dielectric constant (epsilon'), dielectric loss (epsilon ''), loss tangent (tan (o) over bar), ac conductivity (sigma(ac)), ac resistivity (rho(ac)) and the electric modulus are given in the studied frequency ranges. Experimental, results show that the values of the dielectric parameters are strongly dependent on frequency and voltage. The values of E and E decreased with the increasing frequency, while those of sigma(ac) increased with the increasing frequency. Also, electric modulus formalism has been analyzed to obtain the experimental dielectric data. The results imply that the interfacial polarization can occur more easily at low frequencies and consequently contribute to the deviation of dielectric properties of MIS Schottky diodes.