A theory of low frequency impedance in membranes consisting of several layers is proposed. An approach based on irreversible thermodynamics makes it possible to express the impedance of the system in terms of the phenomenological characteristics of component layers (conductivity, ion transference number, sorption isotherm, etc.). No models and suppositions about concrete mechanisms of binary electrolyte solution component transfer across membrane are used. Expressions for the impedance of multilayer membranes situated in both closed and opened cells are derived. Asymptotics of final results corresponding to relatively high applied frequencies are considered. General ways of using the theory are discussed. It is shown that the proposed theory may be useful in studying sorption, electrochemical, and electrokinetic properties of component layers.