The electrical properties of ion-exchange membranes have been investigated using the network simulation method. A network model is proposed for the Nernst-Planck and Poisson equations describing the ionic transport through an ion-exchange membrane and the two diffusion boundary layers on both sides of the membrane. An electric circuit simulation program is used to solve the network model in order to obtain the steady-state, transient, and small-amplitude ac electrical properties of a cation-exchange membrane in contact with an asymmetric electrolyte solution. The steady-state, chronopotentiometric, chronoamperometric, and small-amplitude ac responses of the whole membrane system have been simulated. The study is mainly intended to analyze the characteristics of the equilibrium and nonequilibrium diffuse double layers in ion-exchange membranes and to quantify some interesting aspects of the nonstationary polarization phenomena occurring at the charged membrane/solution interfaces.