PVB ultrafiltration membranes were first prepared via the well-known phase inversion process, and then treated with HCl to improve their antifouling property. Water contact angle measurement indicated the remarkable increase of membrane surface hydrophilicity, X-ray photoelectron spectroscopy (XPS) confirmed the hydrolysis of butyral groups within the membrane, and scanning electron micrograph (SEM) suggested that acid-treated membranes preserved asymmetric structure. Ultrafiltration results showed that separation performance and antifouling property of PVB membranes were considerably affected by acid treating conditions. Prolonging treating time or increasing HCl concentration could increase surface hydrophilicity effectively and thus render the membranes better antifouling property. (c) 2006 Elsevier B.V. All rights reserved.