Separation of an aqueous solution of HCl + FeCl2 by anion-exchange membrane Neosepta-AFN was investigated in a conventional two-compartment cell. The experiments revealed that this membrane is a. good separator for the mixture mentioned - ferrous chloride is efficiently rejected, while hydrochloric acid permeates well through the membrane. The separation is very efficient at low concentrations of ferrous chloride and high acid concentrations. The separation efficiency of the membrane was evaluated by the partial flux of ferrous chloride. The experiments showed that this partial flux is low, i.e. below 5.6%. It decreases with an increasing acid concentration, but it increases with an increasing concentration of salt in the solution separated. Moreover, the separation process was quantified by the permeability of the membrane based on four concentration dependent phenomenological coefficients. (C) 2008 Elsevier B.V. All rights reserved.