Abstract In this work, palladium–iridium nanowires with a Pd/Ir atomic ratio of 2/1 are synthesized through a facile hydrothermal method. Transmission electron microscopy images show that the palladium–iridium nanowires have a uniform diameter below 2 nm and a rough surface with many atomic steps. The electro-catalytic performance of the carbon supported palladium–iridium catalyst towards oxygen reduction reaction has been examined in 0.1 M HClO4 solution. The carbon supported palladium–iridium catalyst displays comparable catalytic activity but much higher durability in comparison with those of the commercial carbon supported platinum catalyst. The excellent electro-catalysis might be attributed to the high accessible area, rough surface and iridium introduction. The work demonstrates that palladium–iridium nanocrystals are promising electro-catalysts for oxygen reduction electro-catalysis in acid media.