A study on the electric properties of reverse osmosis composite membrane was conducted by wet impedance method. The thin film of composite membrane was prepared by interfacial polycondensation with 1,3-phenylene diamine and 1,3,5-benzene tricarbonyl chloride, The electric resistance and capacitance of polyamide skin layer of composite membrane was analyzed by alternating current. The dielectric constant of membrane was also analyzed and compared with theoretical value. Concentration and dipping time of aqueous phase play major role in electrical properties of membrane. The effect of acid treatment on membrane properties was also investigated.