THIS INVENTION 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 RESPECTCELLULOSE 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 520 PSI AND FEED TEMPERATURE 25 -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 91% AND FLUX 210.19 ML.H’1. IN’2. HIGH WATER PURITY WAS OBTAINED BY PRE-PASSING THE SALTED WATER THROUGH MEMBRANE MADE FROM DISSOLVED SOLUTION AND PMMA, INSTEAD OF ION EXCHANGER, WHEREAS THE SALT REJECTION INCREASED TO ~ 98%. ALSO, BY THIS APPROACH THERE IS NO ANY PROBLEM RESULT FROM APPLICATION SUCH MEMBRANE IN WARM COUNTRIES (HIGH THERMAL STABILITY