This present work focused on preparation of economic and high performance reverse osmosis membranes, characterized by high transport properties (salt rejection and flux) towards desalination of brackish water. In this respect cellulose acetate from sugar-cane bagasse (BCA) and polymethyl methacrylate (PMMA) wastes were used as the substrates of membrane. The function of PMMA for enhancing the performance of bagasse-based cellulose acetate RO-membranes was investigated at operating pressure 35.85 bar and feed temperature 25 degrees C. The effects of casting solution, percentage of polymer and treatment of polymer by alkali (HPMMA) on the performance of RO-membrane were discussed. The preferable composition (wt.%) of the 90% BCA and 10% HPMMA was achieved salt rejection 92.18% and flux 325.91 h(-1) m(-2). High water purity was obtained by pre-passing the salted water through membrane made from dissolved bagasse (methylol cellulose) together with PMMA, instead of ion exchanger, followed by passing the accepted water through BCA-HPMMA membrane, whereas the salt rejection increased to similar to 98%. Also, by this approach we obtained high thermal stability membrane compared to CA-RO-membrane. This data gives highlight on possibility of application such type of membrane with high temperature operation conditions. (C) 2007 Elsevier B.V. All rights reserved.