In the present work, the effect of different operating parameters such as frequency of irradiation, intensity of irradiation, initial radius of the cavity, the gas content of the cavity and the operating temperature on the cavitational activity has been studied in a trip I e-frequency sonochemical reactor using numerical solutions of the cavity dynamics equations. The typical range of these operating parameters has been selected based on the experimental evidences (i.e. most commonly used range of operating parameters in actual practice) so as to get a realistic picture about the likely effect of the operating parameters in the sonochemical reactors. Comparison of the obtained trends in terms of the variation in the cavitational activity with the experimental results (some in the present work whereas some earlier published experimental results) has enabled us to give some recommendations regarding the optimum set of operating parameters. It has been observed that the cavitational activity is maximum when a combination of lower frequencies at higher intensity of irradiation is used as compared to the higher frequencies and lower intensities of irradiation and the operating conditions are such that lower initial size nuclei are generated in the system. Also conditions of lower operating temperature and an optimum gas fraction are suitable for the generation of higher cavitational activity. The present study should help in the efficient design and operation of the multiple-frequency sonochemical reactors for obtaining maximum cavitational efficacies. (C) 2004 Elsevier Ltd. All rights reserved.