A high electrocatalytic activity of RuO2 has been found for oxygen reduction reaction (ORR) in the cathode of direct borohydride fuel cells (DBFCs). The electron transfer number n during the ORR changes from 3.58 to 3.86 and the percentage of the intermediate product H2O2 decreases from 20.8% to 7.2% correspondingly when the disk potential scans negatively from -0.39 V to -0.8 V versus Hg/HgO. Peak power densities of 425 mW cm(-2) has been obtained at 60 degrees C, when RuO2 has been used as a cathodic catalyst in DBFCs. RuO2 displays low sensitivity to the BH4- oxidation in DBFCs. Moreover, RuO2, as a cathodic catalyst, demonstrates a superb stability during a 200-h durability test. The identical X-ray diffraction (XRD) patterns of the RuO2 before and after the durability test also prove its stability. (C) 2014 Elsevier B.V. All rights reserved.