Hybrid films composed of electropolymerized luminol-flavin adenine dinucleotide (FAD) adsorbed film modified electrodes have been prepared in aqueous acidic solutions. These films are stable and electrochemically active, and can be produced on glassy carbon, platinum, gold, and transparent semiconductor tin oxide electrodes. The hybrid poly(luminol)/FAD film showed two redox couples. Electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of hybrid poly(luminol)/FAD and poly(luminol) films. The modified electrode was transferred into various aqueous acidic solutions, the two redox couples and the formal potentials of the hybrid films were observed to be pH-dependent. The electrocatalytic oxidation and reduction of NADH and NAD(+) by a polyluminol/FAD hybrid film in aqueous solutions with various pH were carried out. The electrocatalytic oxidation of NADH and the reversible electrocatalytic reactions of NADH/NAD(+) using a poly(luminol)/FAD hybrid film were found to be active. (c) 2006 Elsevier B.V. All rights reserved.