In the present study, degradation of petroleum industry wastewater has been investigated through laboratory experiments by employing heterogeneous photocatalytic process. A photocatalytic reactor was used for the advanced oxidation. The industrial wastewater was characterized. Photocatalytic activity of semiconductor such as titanium dioxide (TiO2) has been investigated. An attempt has been made to study the effect of process parameters through amount of catalyst, and operating pH on photocatalytic degradation of petroleum industry wastewater. The experiments were carried out by varying pH (2-11), amount of catalyst (0.25-1.5 g/L). Optimal suspended catalyst concentration, fluid pH and temperature were obtained at amounts of near 1 g/L, 3 and 50 °C, respectively. The maximum rate of degradation was observed in acidic medium at pH 3 and maximum reduction in chemical oxygen demand (COD) of 60%. © 2015 Scientific Publishers.