Some properties of an anion-exchange membrane, ADS (Morgane-Solvay), were studied in aqueous solutions containing both sodium chloride and sodium benzenecarboxylate or benzenesulfonate. Measurements of electric resistance, water content, ion-exchange and self-diffusion flux were performed as a function of the organic salt concentration (10(-3) to 10(-1) M) in the external aqueous solution. The membrane affinity is greater for benzenesulfonate than benzenecarboxylate ion. The electric resistance decreases when the Cl- counter-ions are substituted by these organic ions more hydrophobic and less mobile. The self-diffusion flux of the Cl- ion through the membrane are strongly dependent on the water content and the concentration of this inorganic anion inside the membrane.