Hydrophilic nanotiltration membranes were prepared by UV-assisted graft polymerization of hydrophilic monomers onto the surface of ultrafiltration membranes made of cardo polyetherketone (PEK-C). The effect of irradiation time and monomer nature on the membrane performances was investigated. Analyses by Fourier transform infrared in attenuated total reflection mode, contact angles of the modified-membrane surface showed that the grafting degree and the hydrophilicity increase with the irradiation/grafting time or irradiation intensity. It was found that the UV-assisted grafting can be performed on the PEK-C chains with or without benzophenone (BP). The grafting inside the pores of the UV sensitive PEK-C membrane is demonstrated by the change of the membrane retention characteristic from that of an UF membrane to that of a nanofiltration membrane. The retentions to sodium chloride and sodium sulfate of the membrane with poly(acrylic acid) grafted for 90 min. UV irradiation under a 1.6 mW/cm(2) irradiation were 36% and 94.1%, respectively, while the water flux through the membrane was ca. 31.3 L m(-2) h(-1), at 0.4 MPa. (c) 2006 Elsevier B.V. All rights reserved.