Abstract o-chloroaniline (o-CA) is a priority organic pollutant that exists widely in industrial pesticide wastewater. Recent reviews on the wastewater treatment methods for the pesticide industry indicate that the treatment methods utilized do not always lead to complete degradation of o-CA. The photocatalytic degradation behaviour of o-CA has been studied in the presence of a catalyst. The effects of the kind of catalyst, pH of the solution and the influence of dissolved oxygen have been examined. After treatment, the organic pesticide wastewater with chloroanilines was non-toxic, and chloroanilines were almost completely degraded after a certain period of irradiation (photodegradation up to 98%, COD removal up to 62.6%.) Experiments on photocatalytic degradation of o-CA with sunlight showed a promising route for pesticide wastewater treatment.