Poly (vinyl) chloride (PVC)-based proton conducting polymer electrolytes have been prepared by solution cast technique. The effect of addition of ethylene carbonate (EC) as the plasticizer on the structural property of the prepared proton conducting polymer electrolyte system was investigated by X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while its effect on electrical property was investigated by Impedance Spectroscopy (IS). With addition of plasticizer, the crystalline nature of the polymer was found to be disrupted as revealed by X-Ray diffraction. FTIR showed interactions between Cl- and H+ which was accounted by shifts in the bands of Cl-. Ionic conductivity was found to be 3.06 x 10 -5 S cm-1 at room temperature (300 K) for the films containing 95 wt. % (PVC -NH4CF3SO3) –5 wt. % EC.