The ultrasonic degradation of reactive brilliant red K-2BP (K-2BP) in water with CCl4 enhancement was investigated. The effects of operating parameters, such as CCl4 dosage, ultrasonic power, media temperature, dye initial concentration, and initial media pH on K-2BP degradation were discussed. The ultrasonic degradation of K-2BP was obviously enhanced by CCl4 addition an effect attributed to the increased (OH)-O-center dot radical concentration in the presence of CCl4 as a hydrogen atom scavenger, and the formation of chlorine-containing radicals. The main degradation products of K-2BP were tentatively identified by GC-MS and ion chromatography. A possible degradation pathway for K-2BP was also proposed. (C) 2011 Elsevier B.V. All rights reserved.