Nanosized Bi2WO6 catalyst exhibited the enhanced photoactivity for the degradation of 4-chlorophenol (4-CP) under visible irradiation compared to the sample prepared by high-temperature solid reaction. The photoactivity of the catalyst was sensitive to pH variation of the suspension. Nanosized Bi2WO6 catalyst showed the highest activity at pH 7.2. The photodegradation of 4-CP by nanosized Bi2WO6 catalyst followed a pseudo-first-order reaction. After three recycling runs for the photodegraclation of 4-CP, the activity of the catalyst did not show any significant loss, suggesting that the catalyst was stable under visible irradiation. (C) 2007 Elsevier Ltd. All rights reserved.