A numerical analysis tool for the estimation of boron reduction, in reverse osmosis (RO) desalination plants, was developed. The derived model enables proper variations of some controllable parameters for significant permeate boron reduction. These parameters are: temperature, applied pressure, permeate splitting along the membranes module and pH changes of the feed. Upon verification of the present model with existing data, parametric reduction of the permeate boron concentration was calculated. It was found that lowering the RO desalination temperature, increasing the applied pressure and/or increasing pH, result in reduction of the permeate boron concentration. The optimal permeate splitting was found to be around half of the module length. Effects of the above controllable parameters on membrane functions, in regard to other permeate variables, are also analyzed and discussed. It was shown that combining contributions of several parameters may yield significant permeate boron reduction to an extent of possible saving a second desalination stage or ion exchange. The present model provides a basis for cost analysis of the required change of the parameters to gain a significant reduction of the permeate boron concentration. (C) 2004 Elsevier B.V. All rights reserved.