BACKGROUND: Atypical approach for removing As from drinking water includes a pre-oxidation step to transform the more toxic As(III) to As(V) and a subsequent separation process for As(V) removal. Unfortunately, typical oxidants result in the formation of toxic oxidation by-products, so alternative options, such as TiO2 photocatalysis, have been investigated. But As(V) produced by oxidation of As (III) remains adsorbed on the catalyst surface, thus limiting process efficiency. In this work a new catalyst based on molybdenum oxide supported on titania (MoOx/TiO2) was investigated to overcome this drawback. RESULTS: The complete photocatalytic oxidation of As(III) (5 mg L-1) to As(V) took place after 120 min exposure to UV-A light. Moreover, the removal of As(V) by adsorption treatment downstream of the photocatalytic process was more effective (90% by gamma-Al2O3 after 10 min) compared with the combined photocatalysis-adsorption process. Finally, the experimental set-up with UV LED irradiation was found to be more effective (96% As(III) converted) than the UV-A light system (75% As(III) converted). CONCLUSION: Photocatalytst did not adsorb As(V) which was completely released into the solution, thus preserving its surface activity and, consequently, drastically reducing operating costs related to catalyst reactivation. (c) 2014 Society of Chemical Industry