The electrical properties of ion-exchange membrane systems with a bi-layer distribution of the fixed-charge inside the membrane, have been analyzed by using the network simulation method. The system under study is constituted by an inhomogeneous membrane with a bi-layer distribution of the fixed-charge and two diffusion boundary layers on both sides of the membrane, the ionic transport of a symmetric 1:1 electrolyte being described by the Nernst-Planck and Poisson equations. The steady-state, transient and small-amplitude ac responses of the membrane system, have been obtained. The influence of the degree of inhomogeneity of the membranes on the steady-state current-voltage characteristic, the electrochemical impedance and the chronoamperometric response of the system, has been analyzed and discussed. (C) 2010 Elsevier B.V. All rights reserved.