Surfactin is an acidic lipopeptide with amphiphilic character, which can interact with a biomembrane. The interaction of surfactin with a supported bilayer lipid membrane on a glassy carbon electrode (GCE) was investigated by cyclic voltammetry and ac impedance spectroscopy in this paper. Surfactin could induce pores in the bilayer lipid membrane and even cause the destruction of the membrane. The mechanism of the interaction of surfactin with the supported bilayer lipid membrane was studied. The insertion of surfactin into the lipid membrane was the first step in the formation of pores. Subsequently, surfactin aggregated in the lipid membrane to form the pores. Along with the transition of surfactin molecules from the outer to the inner layer, which was connected to the surface of the GCE, the lipid membrane was destroyed. (c) 2004 Elsevier B.V. All rights reserved.