Novel ruthenium electrocatalysts for the oxygen reduction reaction (ORR) were prepared by pyrolysis of Ru-3(CO)(12) in three atmospheres: neutral (N-2), partially oxidative (air) and partially reductive (70:30 N-2/H-2), at temperatures in the 80-700 degrees C range. The materials were characterized by FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy. A thermogravimetric analysis of the Ru-3(CO)(12) precursor in the three atmospheres was also performed. The electrocatalytic properties of the materials were evaluated by rotating disk electrode measurements in 0.5 mol L-1 H2SO4. The kinetic parameters, such as the Tafel slope, exchange current density and charge transfer coefficient, are reported. The catalysts prepared in N-2 and N-2/H-2, in general, show a higher performance than those synthesized in air. In the two nitrogen containing atmospheres, a pyrolysis temperature of 360 degrees C seems to lead to better electrocatalytic properties for the ORR. The new electrocatalysts are also tolerant to methanol concentrations as high as 2.0 mol L-1. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.