An electrochemical study of a deposition membrane Of L-glutathione (GSH) and cetylpyridinium bromide (CPB) at polycrystalline Ag electrodes has been carried out. It is found that a deposition membrane containing GSH and CPB can form at the Ag electrode after deposition at 0.05 V (vs. SCE) from a solution containing both compounds, and this has been confirmed by cyclic voltammetry, IR and XPS spectroscopy. At pH 9.7, this deposition membrane gives a well-defined cathodic peak at about -1.1 V, accompanied by the appearance of multiple anodic peaks. Further investigation suggests that the cathodic peak should he attributed mainly to the reduction of CPB rather than the reductive desorption of GSH. The influence of deposition potential, deposition time, CPB concentration, pH and concentration of base solution and other surfactants on the transfer reaction of the deposition membrane were all investigated, and information on the formation of the deposition membrane was obtained. Many thio compounds and surfactants have been used for comparison. It was found that both the mercapto and carboxy groups play important roles in the formation of the mixed deposition membrane. (C) 2004 Elsevier B.V. All rights reserved.