Photo-, sono-and sonophotocatalytic degradation of methylene blue using Abstract. This paper is reporting the sonophotocatalytic degradation of Reactive Red 120 (RR120) under UV light and in the presence of TiO 2 enhanced by ultrasonic irradiation. The result then was compared with photocatalytic degradation. The effects of pH, catalyst loading and initial dye concentration on the degradation rate were studied. In this study, degradation experiments were performed using photoreactor system which comprised a batch photoreactor, UV lamp and ultrasonic mist probe. The probe was used in order to introduce the effect of ultrasonic irradiation in the photoreactor system. The degradation efficiencies of sonophotocatalysis system were obviously depend to the parameter conditions such as pH, catalyst loading and initial dye concentration. Meanwhile, the ultrasonic irradiation in the sonophotocatalysis system enhanced the degradation rate but not changed its trend. Besides, this system exhibited higher rate constant and degradation efficiency compared to photocatalysis system due to an increase in the available surface area or active site of the catalyst and decreasing of mass transfer limitations.