The redox reactions of C-60 fullerene incorporated into a cast film of an artificial lipid (tri-n-dodecylmethylammonium bromide, 3C(12)N(+)Br(-)) on a boron-doped p-type semiconductive diamond electrode were investigated in an aqueous medium. The electrode showed one quasi-reversible and one sigmoidal wave in the cyclic voltammogram. In contrast, three quasi-reversible waves were observed when using a basal-plane pyrolytic graphite electrode. The redox mechanism of C-60 in the 3C(12)N(+)Br(-) film on the diamond electrode is explained using an electron energy diagram. The significance of the surface states in the hole transfer processes from the diamond electrode to C-60 in the lipid film is discussed.