Radical grafting of two monomers, methacrylic acid and polyethylene glycolmethacrylate, onto commercial composite polyamide reverse osmosis membranes was performed. A redox system was used for initiation, and grafting was performed in an aqueous medium at room temperature. Surface grafting was characterized by ATR-FTIR, ESCA and streaming potential measurements. It was found that the membranes were surface modified without damage to their transport properties.