We report the electropolymerization of CuPtBr6 film on the electrode substrate by cyclic scanning in 3 x 10(-3) M CuCl2 + 3 x 10(-3) M K2PtBr6 + 1 M KCl in the potential range from + 700 to - 800 mV (versus the saturated calomel electrode (SCE)). Several surface analysis techniques were used to characterize the film on the electrode surface. A sharp and intense diffraction peak in the X-ray diffraction (XRD) pattern indicates that the film has a high preferential orientation. The electrochemical behavior of the modified electrode was studied in detail in electrolyte solutions containing various cations. On the basis of these studies, a mechanism of electropolymerization was proposed which suggests for the modifier film a one-dimensional, polymeric structure formed from a negatively charged platinum compound, stabilized by Cu2+ and Cu+ as the counter ions. The composition of the modified film is proposed to be [CuPtBr6. CuPtBr4](n), and is denoted as CuPtBr6/glassy carbon (GC) to highlight the starting components. H+/H, Fe3+/Fe2+ and Cr3+/Cr2+ display remarkably reversible redox behaviors at the CuPtBr6/GC electrode. The modified electrode also displays good catalytic activity toward the oxidation of ascorbic acid, hydrogen peroxide, S2O32-, and especially nitric oxide. (C) 2000 Elsevier Science Ltd. All rights reserved.