The hydrolysis of sodium toluene sulfonate (STS) in sub-/supercritical water in the presence of CO2 was investigated using a continuous flow system at the constant pressure of 250 bar. The effect of water flow-rates, reaction temperature and CO2 flow-rates on the hydrolysis of STS was investigated. Results showed that hydrolysis of STS increases with the increase in temperature and CO2 flow rate. The optimum reaction conditions calculated by partial factorial design were 452 degrees C, water flow rate of 2.3 mL min(-1) and CO2 flow rate of 0.08 mL min(-1). Furthermore, supercritical water was used for total removal of STS from industrial wastewater using H2O2 as an oxidant. Results showed that at temperatures higher than 350 degrees C more than 99% of STS is oxidized while COD remains high until reaction temperature of 450 degrees C after which COD of solution diminished 81%. (C) 2015 Elsevier B.V. All rights reserved.