The structurally ordered intermetallic Pd3Fe alloy nanoparticles supported on carbon (O-Pd3Fe/C) are prepared by the impregnation method and employed as the electrocatalyst for the oxygen reduction reaction (ORR). The physical properties of the Pd3Fe nanoparticles are characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. It is revealed that the O-Pd3Fe/C catalyst shows the super lattice characteristics of the long range ordering of Pd and Fe atoms, confirming the formation of ordered intermetallic phase with face centered cubic structure. The electrochemical properties are evaluated by cyclic voltammetry and rotating disc electrode techniques. The O-Pd3Fe/C catalyst exhibits the significantly improved durability, as well as the specific activity of 2.4 and 2.6 times that of the disordered Pd3Fe/C catalyst and Pd/C catalyst, respectively, at 0.8 V. The performance enhancement is attributed to the formation of ordered intermetallic phase, resulting in the optimal compressive lattice strain and the higher degree of alloying. (C) 2015 The Electrochemical Society. All rights reserved.