The kinetics and mechanisms of the reactions of 2-chlorophenol with hydroxyl radical, azide radical, hydrogen atom and hydrated electron have been studied using pulse radiolysis. In neutral solutions, relatively stable hexadienyl type OH-adducts is formed upon the addition of hydroxyl radical to the aryl ring of the substrate. In alkaline solutions, 2-chlorophenoxyl radical and semi-quinone radical anion are formed through the electron transfer from the substrate to hydroxyl radical as well as OH-addition followed by HCl/OH,-, elimination. Azide radical oxidizes 2-chlorophenol via one-electron transfer, forming correspondent o-chloro-phenoxyl radical. Hydrogen atom reacts with the substrate via the addition to the aryl ring, forming hexadienyl type •H-adducts. Under the attack of hydrated electron, 2-chlorophenol undergoes reductive Cl,-, elimination, with the rate constant of 3.5×10,8,dm,3,•mol,-1,•s,-1,in alkaline solution and 2.2×10,9,dm,3,•mol,-1,•s,-1,in neutral solution respectively. These results shed light on the degradation mechanism of chlorophenols and provide theoretical foundation for treatments of wastewater contaminated with chlorophenols.