To utilize bipolar membrane in water splitting electrodialysis, bipolar membranes were prepared by a paste method using commercial CM1 as cation exchange layer and optimized poly (GMA-DVB-PVC34) as the anion exchange layer. Chemically and thermally stable aromatic pyridinium was introduced as anion exchange functional group. Iron(III) hydroxide was immobilized at the bipolar membrane junction. The effect of iron(III) hydroxide on water dissociation capacity and current efficiency was investigated using a six-compartment electrodialytic cell. The result showed that with the immobilization of iron(III) hydroxide in the intermediate layer, water dissociation was enhanced and comparable to that of commercial BP1. The observed current efficiency for BPM with 5% (w/v) iron(III) hydroxide was more than 95%. (c) 2006 Elsevier B.V All rights reserved.