Cerium-doped tantalum oxide (cerium-Ta2O5) particles were synthesized using a low-temperature hydrothermal method. The crystal structure of the samples was investigated using X-ray diffraction (XRD). The XRD results revealed that the Ta2O5 cells shrunk after cerium doping. The electronic structure of cerium-Ta2O5 was calculated using density functional theory (DFT). The DFT results indicated that the energy band of Ta2O5 was narrow when it was doped with cerium, which might have resulted in the improved electrocatalytic activity of Ta2O5. Therefore, calculation of results could be used as a direct theory by which the electrocatalytic activity of cerium-Ta2O5 may be studied. The electrocatalytic activity of cerium-Ta2O5 was investigated in a KCl solution containinng methylene blue (MB) using cyclic voltammetry (CV). The CV results showed that the cerium-Ta2O5 exhibited excellent electrocatalytic activity toward MB reduction. The cathodic peak potential of MB shifted from -0.22 Von a glass carbon electrode to -0.01 V on a Wcerium-Ta2O5 film electrode. (C) 2012 Elsevier B.V. All rights reserved.