This paper presents the photocatalytic degradation of real refinery wastewater from National Refinery Limited (NRL) in Karachi, Pakistan, using TiO2, ZnO, and H2O2. The pretreatment of the refinery effluent was carried out on site and pretreated samples were tested at 32-37 °C in a stirrer bath reactor by using Ultra-Violet photo oxidation process. The degradation of wastewater was measured as a change in initial Chemical Oxygen Demand (COD) and with time. Optimal conditions were obtained for catalyst type, and pH. The titanium dioxide proved to be very effective catalysts in photocatalytic degradation of real refnery wastewater. The maximum degradation achieved was 40.68% by using TiO2 at 37 °C and pH of 4, within 120 minutes of irradiations. When TiO2 was combined with H2O2 the degradation decreased to 25.35%. A higher reaction rate was found for Titanium dioxide. The results indicate that for real refinery wastewater, TiO2 is comparatively more effective than ZnO and H2O2. This study proves that real refinery wastewater reacts differently than synthetic refinery wastewater, oil field produced water or oil water industrial effluent.