The extraction of Na+, Ni2+, and Cr3+ using six different membranes made of polyaniline composited withhigh-impact polystyrene, which differ in the doping agent and/or the preparation method, has been investigated.The swelling and ion-exchange capacities of the six polyaniline composited with high-impact polysterene(HIPS/PAni) membranes have been determined and compared with that of the commercial Selemionmembrane. Electrodialysis tests using a five-compartment cell evidenced that the extraction of ions dependson the electronic structure of the SO3- groups, which is modulated by the doping agent, and on bothmicrostructure and electrical resistance of the membrane, which are regulated by the preparation method.The transport of ions through HIPS/PAni and Selemion membranes was found to be comparable. Quantummechanical calculations on model complexes have been performed to characterize the electronic structureof the dopants. Results indicate that the strength of the interaction between the different doping agents andthe polyaniline is inversely proportional to the concentration of negative charge in the SO3- group of theformer. Moreover, both the binding energy and the distribution of charges calculated for dopant · · · PAnicomplexes have been compared with those predicted for dopant · · · metallic ion complexes.