In this study, the effect of pH as a function of number of membranes employed on boron removal from geothermal water containing boron was investigated by using a mini-pilot scale brackish water reverse osmosis (BWRO) system. When the pH of geothermal water was increased to 10.5, boron rejection obtained was 94.5-95% for both single and double membrane configurations at 12 bar of operating pressure. At pH 10.5, the boron concentration of the product water was around 0.5 mg/L which is suitable according to irrigation standards. On the other hand, it was observed that the average permeate flux and water recovery values decreased when the pH of feed water was increased from 8.0 to 10.5 for both single and double membrane configurations. (C) 2012 Elsevier By. All rights reserved.