A convenient and simple sol-gel method has been developed for the synthesis of anatase TiO2 and Codoped TiO2 nanoparticles. The samples were characterized by XRD, XPS, UV-vis DRS and it was found that the dopant ions replaced some of the crystal lattice titanium ions, existing in the form of Co2+. UV-vis DRS confirm that the obtained ColTiO(2) samples have an extended light absorption range compared with pure TiO2. Photocatalytic activities of the catalysts were assessed based on the degradation of single rhodamine B (RhB) and mixed dyes in aqueous solution in the present of visible light (lambda > 420 nm). With an optimal molar ratio of 1% (Co/Ti), the sample shows the highest rate photodegradation efficiency under the same experimental conditions. SPV was used to investigate photophysical mechanism of the visible light photocatalytic activity and revealed that there is an electronic interaction between the Co and TiO2, which plays a significant effect in improving the efficiency of photocatalysis. (C) 2014 Elsevier B.V. All rights reserved.