Wastewater treatment by conventional methods as ion exchange, coagulation and precipitation is very important. A relatively new method for wastewater treatment is introduced; this method is known as electrically switched ion exchange (ESIX). ESIX can be used to separate metal ion contaminants from industrial wastewater. The ESIX method involves sequential application of reduction and oxidation potentials to an ion exchange film to induce the respective loading and unloading of Cs+. The metal ion separated from the wastewater and unloaded from the electrode by modulating the potential applied to the film. This technology is superior to conventional methods (e.g conventional ion exchange) as it requires very little energy for ionic separation. In this study, two films of nickel hexacyanoferrate were prepared on nickel electrodes with different preparation procedures. Each film shows different performance in Cs+ separation. Scanning electron microscopy was used to characterize the modified film surfaces. Cyclic voltammetry was used to investigate the ion exchange capacity and stability. These two films show a high capacity and stability for Cs+ separation.