The reverse osmosis (RO) membrane desalination process is relevant and reliable technology for desalination of geothermal water. However, some serious limitations had recently been discovered during field practice, among them the boron problem seems to have a critical meaning. We have reported that the maximum boron rejection obtained with RO system equipped with commercially available membranes was 49% at 15 bar of applied pressure and pH 8.0. The minimum boron concentration in the product water was still 4.70 mg/L at this condition [8]. On the other hand, water authorities of EU have recommended that the acceptable concentration level of boron in irrigation water should be lower than 1.0 mg/L. Thus, integration of a secondary purification step, such as ion exchange-ultrafiltration hybrid process to the RO system is considered to be useful to reach target values of boron in the product water according to our past experiences. Indeed, we previously checked the performance of such hybrid process for boron removal from geothermal water directly and determined the optimum process parameters and its recyle use [35]. According to the obtained results, it was possible to use ion exchange-ultrafiltration hybrid process for elimination of boron from geothermal water. Thus, we considered that we could apply the hybrid process for elimination of the residual boron from RO permeate of geothermal water this time when RO process is the preferable process for desalination of geothermal water.