Sonolysis is one of the techniques to destroy various organic contaminants in dilute aqueous solutions. The purpose of this study was to examine the effect of alumina particles on the enhancement of sonolysis. Chlorobenzene was chosen as the model organic compound and batch experiments were carried out with 20 kHz ultrasound source. The results showed the acceleration of the decomposition rate was observed and the rate was proportional to the surface area increased by the introduction of the particles. The possible mechanisms for the enhancement were discussed including the increase in the cavitation bubbles which were produced by sonication and the decomposition took place in.