In this study, the effect of frequency and voltage on the dielectric properties of Al/(CdS-PVA)/p-Si structures prepared using cadmium sulfide (CdS)-polivinyl alcohol (PVA) interface material was investigated. For this purpose, real and imaginary permittivity (epsilon' and epsilon ''), dissipation factor (tan delta), ac electrical conduction mechanism (sigma(ac)), real and imaginary part of electric modulus (M' and M") were obtained by using capacitance-conductance (C-G/omega) measurements at frequency between 5kHz - 5MHz and at voltage between (-1V) - (+1V). All parameters were found to depend considerably on the frequency and voltage. epsilon' and epsilon '' reach higher values at low frequencies due to surface states (N-ss) which can easily monitor ac signal, dipolar polarization and interfacial polarization. Short-range mobility of charge carriers caused the increase of both electrical modulus and sigma(ac) with increasing frequency. Moreover, M '' exhibited a peak behavior which shifts to higher frequency with increasing voltage. Peak behavior could be ascribed to both decrease in polarization and surface states. (C) 2020 Elsevier B.V. All rights reserved.