BACKGROUND: Photocatalysis is one of the advanced oxidation processes that has gained in importance over recent years owing to its ability to decompose a wide range of organic and inorganic pollutants at ambient temperature and pressure. However, there are two essential issues regarding photocatalytic processes, i.e. limitations on photon transfer and on mass transfer. In the present study, a novel photo-impinging streams reactor, which can minimize such limitations, has been utilized in the photocatalytic degradation of phenol. The design and operating parameters such as type of nozzle, flow rate, catalyst loading, pH, initial phenol concentration and light intensity were found to have the expected impact on the efficiency of the process. The effects of two different co-oxidants, H2O2 and Na2S2O8 on the photocatalysis were also examined. RESULTS: Results indicated that 100 mg L-1 of phenol in a 750 cm(3) solution was completely degraded within 2.5 h reaction time in the presence of TiO2 without a co-oxidant present; and within 1 h in the presence of a co-oxidant. CONCLUSION: A comparison between the current data and those available in the literature revealed higher efficiency and increased performance of the present reactor relative to conventional apparatus. (C) 2010 Society of Chemical Industry