A novel charge-transfer compound (TMB)(3)PMo12O40 (TMB-PMo12, TMB = 3,3',5,5-tetramethylbenzidine) was synthesized. There is a strong electronic interaction between organic donor TMB and PMo12O403-heteropoly anion. Irradiation of ultraviolet light can cause the intramolecular electron-transfer between TMB and heteropoly anion in the complex. Electrochemical behavior of the TMB-PMo12 modified electrode in H2SO4 solution showed well-defined redox couples corresponding to the redox reactions of the incorporated TMB and heteropoly anion. The TMB-PMo12 modified electrode exhibits excellent catalytic activity for the reduction of IO3-, where the incorporated TMB may play an important role to activate the catalytic activity of the heteropoly anion. (c) 2006 Elsevier B.V. All rights reserved.