The kinetics and mechanism of ozonation degradation of p-nitrochlorobenzene（pCNB）were investigated.The reaction rate constant of pCNB with O3 was 1.6 L·mol-1·s-1 by direct determination.With nitrobenzene and chlorobenzene as the reference compounds

the reaction rate constant of pCNB with ·OH that was determined by means of competition kinetics was 2.6×109 L·mol-1·s-1.During the pCNB ozonation degradation

organic nitrogen and organic chlorine were almost completely converted to nitrate and chloride.Ozonation could not reduce TOC obviously.The results of LC-MS and GC-MS showed that the main intermediate products were aromatic substances such as p-chlorophenol

p-nitrophenol

2-chloro-5-nitrophenol

etc.

and non-aromatic substances such as oxalic acid

malonic acid

maleic acid

muconic acid etc.Finally

a possible reaction pathway of ozonation degradation of pCNB was proposed according to these intermediate products.