Morphological and structural changes on anion selective membrane Selernion(1) AMV and cation-exchange-membrane Selemion CMT were evaluated, when these membranes were in contact with solutions containing zinc complexes. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and thermogravimetric analysis (TGA) were used to investigate the membranes. The effect of interactions among zinc complexes and membranes on the ionic transport was evaluated. To this investigation, the sodium ion transport, through the anion-exchange-membrane AMV, and the cyanide transport, through the cation-exchange-membrane CMT, were analysed. Two solutions were used on this paper: alkaline (NaOH) and alkaline with cyanide (NaCN). Results show an important loss of permselectivity of the ion-exchange membranes in the presence of zinc-cyanide complexes, what demonstrates that the interactions among complexes and membranes can cause significative changes on these membranes. (c) 2005 Elsevier B.V. All rights reserved.