TiO2 nanoparticles co-doped with different doping concentration of Pr and N were prepared by sol-gel method combined with microwave chemical method. The samples were characterized by XRD, UV-vis, TEM, XPS, PL, and the photocatalytic activity were investigated by photocatalytic degradation of methylene blue (MB). The results indicate that Pr and N ions incorporate into the lattice of TiO2, co-doping restrains the increase of grain size, broadens the absorption region to visible light, and inhibits the recombination of the photo-generated electrons and holes. Moreover, the photocatalytic activity of Pr-N-TiO2 is remarkable improved due to the synergistic effect of the co-doped ions. The degradation rate of MB in 6 h is 92.81%, which is much higher than that of Degussa P25 (45.01%). (C) 2011 Elsevier Ltd. All rights reserved.