Nanofiltration (NF) has been used as pretreatment to reverse osmosis (RO) desalination processes for lowering the required pressure. In this work, a novel kind of amphoteric thin-film composite (TFC) NF membranes were prepared through a method of coating and cross-linking using sulfated chitosan (SCS), polysulfone (PS) ultrafiltration (UF) membrane, and epichlorohydrin (ECH) as the active layer material, the base membrane, and the cross-linking agent, respectively. At 0.40 MPa and ambient temperature, the rejections of the resultant membrane to Na2SO4 and NaCl solutions (1000 mg L-1) were 90.8% and 32.5%, while the permeate fluxes were 22.9 and 58.4 kg m(-2) h(-1), respectively. The structure and morphology of the resultant SCS/PS composite NF membranes were characterized with attenuated total reflection infrared spectroscopy (ATR-IR), environmental scanning electron microscopy (ESEM), and atomic force microscopy (AFM). The rejection performances suggested that SCS/PS composite NF membranes cross-linked by ECH have a potential for the separation of mono/divalent inorganic electrolytes from low-molecular-weight organics. (C) 2012 Elsevier Ltd. All rights reserved.