In this work, we have tried to improve the surface and antifouling properties of polyethersulfone (PES) membranes coated by a thin layer of chitosan. Acrylamide (AAm) as a grafting agent and microwave-assisted grafting as a physical procedure were employed to grafting of the chitosan thin layer without using any chemical initiator. Different acrylamide concentrations (1.8, 3 and 4.2 wt.%), irradiation times (0, 10, 30 and 60 s) as well as irradiation powers (180, 360 and 520 W) were employed. The modified membranes showed an outstanding antifouling property for bovine serum albumin (BSA) in some conditions of preparation. The separation properties of the thin film composite membranes for ion solutions (NaCl, Na2SO4 and MgCl2) increased and changed. Water contact angle measurement, ATR-IR apparatus, SEM, AFM and membrane filtration set-up were used for supporting the results. We used Taguchi designs to analyze many factors with few runs. (c) 2013 Elsevier B.V. All rights reserved.