The interfacial and electrochemical behaviour of diphenyldiselenide (Phi(2)Se(2)) on the hanging mercury drop electrode has been studied by means of cyclic and ac voltammetry and chronocoulometry using 30% dimethylformamide-water media. Both capacitance and Faradaic current measurements reveal that a progressively thicker multilayer film is formed as a result of chemisorption of Phi(2)Se(2) at the mercury/solution interface. By controlling the thickness of the film, a gradual inhibition of the electrochemical reduction of Ru(NH3)(6)(3+) is achieved. (C) 2003 Elsevier Ltd. All rights reserved.