Quantum-sized ZnO particles supported on sepiolite (ZnO/sepiolite) was prepared by sal-gel method using the sepiolite of acid activation as carrier, zinc acetate dihydrate (Zn(CH3COO)(2)center dot 2H(2)O) and lithium hydroxide monohydrate (LiOH center dot H2O) as raw material. The size of ZnO which supported on fibrous sepiolite is about 5 nm when calcined at 200 degrees C. The behavior of ZnO/sepiolite composites in the degradation of C.I. Reactive Blue 4 was investigated. Under the optimal preparation conditions, when the content of ZnO was about 70 wt.% in the nanocomposites, the photocatalytic property of the ZnO/sepiolite was excellent. The degradation rate of 20 mg/L C.I. Reactive Blue 4 could get to 98% in 120 min at room temperature when the concentration of catalyst was 0.2 g/L. The photocatalytic decomposition of organic pollutants accords with a pseudo first-order kinetic. The pH and H2O2 influence the degradation rate of the ZnO/sepiolite. The experiment indicated that after the catalyst had been used 5 times repeatedly, the degradation rate had been still above 80%. (C) 2010 Elsevier Inc. All rights reserved.