Powder of RuxCrySez electrocatalyst was prepared from decarbonylation of the transition-metal carbonyl compounds in an organic solution containing dissolved selenium. The synthesized catalyst was characterized by FT-IR, X-ray diffraction (XRD), SEM and electrochemically. The powder catalyst presents high uniformity of cauliflower-like agglomerates of nanocrystalline particles embedded in an amorphous phase. The electrocatalysis of the oxygen reduction at this material on the ink-type electrode in acid electrolyte was studied by using the rotating disk electrode (RDE) technique. The RuxCrySez catalyst presented attractive catalytic activity for the oxygen reduction reaction, ORR, in 0.5 M H2SO4. The Tafel slope for the ORR remains constant with temperature at -0.117 V dec(-1) and the charge transfer coefficient increases in da/dT= 1.8 x 10(-3), attributed to entropy turnover contribution similar to those reported on ruthenium-based selenide catalysts. The effect of temperature on the kinetics of ORR was analyzed and an apparent activation energy of 40.6 kJ mol(-1) was determined. The performance achieved from the hydrogen-oxygen polymer electrolyte membrane fuel cell (PEMFC), with cathode of RuxCrySez catalyst operating at different temperatures, was evaluated. (c) 2005 Elsevier B.V. All rights reserved.