The degradation of 2chloro-5methyl phenol (2C-5MP) in aqueous solution by ultrasonication (US) in the presence of TiO2 and H2O2 has been studied. Maximum degradation rate of 2.66 x 10(-2) was achieved by US/TiO2/H2O2 process when compared to US/TiO2 (1.01 x 10(-2)) and US/H2O2 (5.5 x 10(-3)) systems. The effect of inorganic ions on degradation rate of 2C-5MP were found to be in the order of Cl- > SO42-> HPO42- > HCO3-. Further, the impact of synthetic additives like CCl4 as hydrogen radical scavenger and CH3OH as hydroxyl radical scavenger on US were studied which confirmed the involvement of hydroxyl radicals in the degradation of 2C-5MP. Kinetic studies revealed that the degradation process followed pseudo-first-order mechanism with the correlation coefficient (R-2) of 0.9913 under experimental conditions. (C) 2009 Elsevier B.V. All rights reserved.