Photo-degradation of tributyltin (TBT) has been enhanced by TiO2 nanoparticles doped with nitrogen (N-doped TiO2). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 degrees C. X-ray diffraction results showed that N-doped TiO2 remained amorphous at 300 degrees C. At 400 degrees C the anatase phase occurred then transformed to the rutile phase at 600 degrees C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO2 calcined at 400 degrees C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light When compared with undoped TiO2 and commercial photocatalyst, P25-TiO2 which gave 14.8 and 18% conversion, respectively. (C) 2010 Elsevier B.V. All rights reserved.