Electrochemically active 1,4-bis(3,4-dihydroxyphenyl)-2,3-dimethylbutane (nordihydroguaiaretic acid, NDGA) films can be directly deposited on Nafion modified electrodes from aqueous nordihydroguaiaretic acid. The deposited NDGA/Nafion films are stable, and show obvious electrochemical activity in aqueous solutions with various pH. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the NDGA/Nafion films. When freshly prepared NDGA/Nafion films were transferred to aqueous solutions at various pH, the formal potential was found to be pH dependent. The NDGA/Nafion films electrocatalytically oxidized dopamine, epinephrine, and norepinephrine in aqueous solutions, with the electrocatalytic oxidation current developing through the oxidized form of the NDGA/Nafion film. NDGA/Nafion films also showed reversible electrocatalytic properties. Such films electrocatalytically reduce the oxidation products of dopamine, epinephrine, and norepinephrine resulting from the electrocatalytic oxidation of these compounds by the NDGA/Nafion film. The NDGA/Nafion modified films also electrocatalytically oxidized a mixture of dopamine and ascorbic acid. The chemical reaction of dopamine quinone with ascorbic acid was investigated using the rotating ring-disk electrode method. (c) 2005 Elsevier B.V. All rights reserved.