Iridium catalyst was prepared by a direct gas phase reduction method. The phase composition of iridium was analyzed by X-ray diffraction, and the electrochemical performance was evaluated by cyclic voltammetry (CV) and linear scanning voltage (LSV). The result of XRD shows that iridium is transformed completely from iridium oxides after 400 °C reduction for 3 h under ammonia atmosphere. According to the result of CV and LSV, iridium possesses favorable electrocatalytic activity for oxygen reduction. The onset potential of iridium for oxygen reduction reaction (ORR) achieves 0.51 V (vs. SCE). From the viewpoint of atomic states, the number of d-band vacancy of iridium is more than that of platinum which leads to the lower electrocatalytic activity of iridium than that of platinum, but the two electrocatalysts have the similar electrocatalytic paths for ORR