Groundwater contaminated by nitrate has become a worldwide problem. Existing technologies for nitrate removal, including zero-valent iron reduction, can only transform nitrate ions to predominantly NH4+. As a result, many studies have concentrated on seeking a solution to convert nitrate to N-2. In this study, the efficiencies of nitrate removal from aqueous solution by single (TiO2 and nano zero valent iron, nZVI), and composite (Nano-TiO2-Fe-0 composite, NTFC) system under UV illumination were prepared. Among the three systems, both nZVI and NTFC can effectively remove nitrate. However, only NTFC can achieve satisfactory transformation of nitrate to N-2. Further investigation has proven that the composition of NTFC (TiO2/nZVI ratio) greatly influences the conversion of nitrate to N-2, which can be attributed to the maintenance of high level of ferrous ions in the NTFC system due to its reducing condition. (C) 2011 Elsevier B.V. All rights reserved.