5-Aminoisoquinoline (AIQ), a bifunctional monomer, having an aniline type -NH2 group and a -C=N-C group in quinoline ring, was specifically electropolymerized utilizing the -NH2 groups to leave the -C=N-C groups in the ring intact in the resulted polymer. Electrochemical characteristics for the polymerization of mixture of aniline (ANI) and AIQ was investigated via cyclic voltammetry. Individual electrochemical homopolymerization studies for ANI and AIQ were also performed to deduce the changes in the electrochemical characteristics during polymerization with ANI and AIQ together. X-ray photoelectron spectroscopy (XPS) was employed to find the elemental composition and proportion of reduced units in the copolymer. The presence of -C=N-C groups in the copolymer is evident from XPS and in situ spectroelectrochemical results. Double potential chronocoulometry was used to obtain the diffusion characteristics of the copolymer film modified electrode. Oxidation of hydroquinone was performed on the copolymer film modified electrode. (C) 2002 Elsevier Science B.V. All rights reserved.