The nanopaticles of TiO2 doped with nitrogen and cadmium are synthesized by sol-gel method followed by 2h calcination at 400 degrees C in air atmosphere. Its chemical composition and optical absorption are investigated by XRD, UV-vis absorption spectra, TEM, XPS and Raman spectra. The results show that nitrogen and cadmium co-doping cause the absorption edge of TiO2, to shift to the visible-light region. The Cd2+ doping hinders the recombination rate of excited electrons/holes and prevents the aggregation of powder during the calcination. Superior catalytic activity of the co-doped TiO2 was observed for the decomposition of rhodamine B under visible light irradiation. The interstitial nitrogen atoms in co-doped TiO2 nanoparticles powder are responsible for the visible light photocatalytic activity. (c) 2007 Elsevier B.V. All rights reserved.