(Copper, Nitrogen)-codoped titanium dioxide (TiO2) nanoparticles have been prepared via a sol-gel route, followed by heat treatment at an elevated temperature. Such (Cu, N)-codoped TiO2 nanoparticles showed a strong absorption in the visible region and a red shift in the band gap transition and exhibited an enhanced photocatalytic activity as compared with the pure, N-doped and Cu-doped TiO2 for xylenol orange decomposition.