Ultrasonic degradation of Basic Red 29 (BR29) textile dye in the presence of Co2+-H2O2 system was investigated in this study. The effects of presence of ultrasonic power, concentrations of cobalt (II) acetate (Co(II)Act) and H2O2, temperature and initial pH on the BR29 degradation were examined. Initial dye concentration of 20 mg/L BR29 was used in the study as a model solution. In sonication experiments, an ultrasonic bath at a frequency of 40 kHz was employed. Best experimental conditions were also obtained in the studies as follows: 1000 mg/L Co(II)Act, 1000 mg/L H2O2, 40 degrees C and original pH of 6.70. According to the results, after 30 min of sonication in the presence of Co2+-H2O2 dye removal efficiency of practically 100% was achieved. It was also found that US enhanced the degradation rate of BR29. (C) 2009 Elsevier B.V. All rights reserved.