The cadmium sulfide (CdS) nanopowders have been prepared by ball-milling method, and CdS-polyvinyl alcohol (PVA) nanocompound in the form of film has been deposited on a p-Si wafer as an interfacial layer by spin-coating method. The impedance characteristics of the fabricated Al/CdS-PVA/ p-Si (metal-polymer-semiconductor)-type structures were studied in the frequency and voltage range of 5 kHz-5 MHz and ±1 V, respectively, by considering interface states (D it ), series resistance (R s ), and interfacial layer effects at 300 K. While the voltage and frequency dependence profiles of D it were evaluated from the low-high frequency capacitance (C LF -C HF ) and Hill-Coleman methods, R s profiles were evaluated from the Nicollian and Brews method. Doping concentration atoms (N A ) and barrier height Φ B (capacitance-voltage (C-V)) values were also obtained from the reverse bias C-2 versus V plots for each frequency. While D it and R s values decrease with increasing frequency almost exponentially, Φ B (C-V) increases linearly. Therefore, both the measured capacitance (C m ) and conductance (G m /w) values were corrected to eliminate the R s effect. The experimental results show that R s value is more effective on the impedance measurements at high frequencies in the accumulation region, but D it is effective at low frequencies in the depletion region.