Membrane based desalination is the proven and established technology for mitigating the increasing water demand. The high flux membrane will require lower pressure to produce the given quantity of water and therefore will consume lower energy. The present paper demonstrates the novel method to produce high flux membrane by surface modification of thin film composite reverse osmosis (TFC RO) membrane. TFC RO membrane was exposed to sodium hypochlorite solution of 1250 mg/l for 30 minutes and 60 minutes at ph 11.0, followed by 1000 mg/l Chitosan for 60 minutes at pH 2.5 and the solute rejection/flux were monitored. It was observed that there is upto 2.5 times increment in flux with ca. 3% increase in solute rejection in case of chitosan treated membrane. Although, the flux increase is more in longer sodium hypochlorite treated membrane, the decline in solute rejection was also significant. The membrane samples were characterized by Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to understand the chemical structural changes in the membrane, atomic force microscope to understand the morphological changes on membrane surface, zeta potential for surface charge and contact angle analysis to understand the change in hydrophilicity. The % rise in trans-membrane flux per o C rise in feed water temperature was more in case of chitosan modified membrane as compared to virgin TFC RO membrane. The higher temperature sensitivity makes it a good candidate for solar powered reverse osmosis where, low grade thermal energy can be utilized to increase the feed water temperature and higher temperature feed water gives more pronounced advantage in trans-membrane flux. Introduction:Thin film composite RO membrane has found numerous applications in desalination and water reuse. Research and development effort in improving its solute rejection and flow performance of the membrane has made the RO membrane versatile for diverse applications. A thin film composite RO membrane consists three layers: the bottom support