Membrane fouling by organic solutes during electrodialysis is a well-known problem, especially during water treatment. Fouling causes an increase in membrane electrical resistance, leading to shortened membrane life and increased energy consumption. This article describes an improvement to the antifouling potential for an anion exchange membrane (AEM) by surface modification with poly-(sodium 4-styrene sulfonate) (PSS). The antifouling potential of the AEM was evaluated by the transition time, i.e. the time elapsed before the fouling took place, using sodium dodecylbenzene sulfonate (SDBS) as a model organic foulant. It was shown that the antifouling potential of the AEM was considerably improved by surface modification with PSS. A mechanism for fouling by SDBS is also theoretically discussed and it is concluded that adsorption of SDBS micelles on the AEM surface was prevented by surface modification with PSS and the antifouling potential was improved because both hydrophilicity and the negative charge density were increased on the modified membrane surface. Additionally, it was confirmed that surface modification with PSS scarcely affects the performance of AEM during electrodialysis. (C) 2012 Elsevier B.V. All rights reserved.