In this study, desalination performance of a mini-pilot scale seawater reverse osmosis (SWRO) system installed at geothermal field was investigated. The system was analyzed in terms of product water quality and quantity using two types of FilmTech SWRO membranes (SW30-2540 and a novel high rejection SWRO membrane abbreviated as XUS SW30XHR-2540). To determine the effect of applied pressure on desalination performance of the SWRO system, the process was operated at different pressures. The boron rejection of SWRO membranes was higher than that of BWRO membranes. An average boron rejection of 88% and a salt rejection of 99% were obtained at 20 bar of operating pressure by a high rejection XUS SW30XHR-2540 membrane. The average permeate recovery by XUS SW30XHR-2540 membrane was about 16% and it increased to 34% at 40 bar of operating pressure. The respective average boron rejection value obtained by SW30-2540 membrane was 84% at 20 bar. The average permeate recovery of SW30-2540 membrane was 20% at 20 bar while it,increased to 37% at 40 bar. The quality of product water obtained by both membranes was good according to water standards. (C) 2012 Elsevier B.V. All rights reserved.