There is an increasing interest in the application of high intensity ultrasound as an advanced oxidation technique. In this study, 1,1,1-trichloroethane (TCA) is the compound being subjected to ultrasonic irradiation. The study focuses on the effects of pressure (0.103–0.241 MPa), temperature (6–19.4°C) and pH (3.96–12.5). Optimum conditions of treatment are discerned from the results of the experiments based on a center composite design. The results show that about 98% of TCA can be removed in 1 h of treatment (starting concentrations average 80 mg/l). Also, experiments indicate that the initial concentration does not affect destruction rate in this system. Optimum conditions as indicated by statistical analysis are at T=14.2°C, P=0.212 MPa and pH=10.9. This study also presents a method to normalize rate constants for changes in the power-to-volume ratio.