The usage of anisomeric square pulse with fluctuating frequency for electrochemical generation of FeO42- has been reported. The cylinder electrolytic bath was constituted by a double cathode and a porous cast iron cylinder anode, using CS-CMC bipolar membrane as septum. Compared with CS or CIVIC membranes, CS-CMC BM has good mechanical strength and chemical stability in acid and alkali solution. FT-IR spectrum indicated that CS-CMC BM contained -N=CRH2+ and -COO- functional groups. The charge density of -N=CRH2+ in CS layer and -COO- in CMC layer was about 14.13 and 9.01 mmol/g, respectively. With the aid of anisomeric square pulse, the oxidation layer was destroyed in time. After 6 h electrolysis, the corresponding current efficiency was 51.2%. (C) 2007 Elsevier B.V. All rights reserved.