A key constituent in developing lithium–air batteries is the oxygen electrode, which facilitates the oxygen reduction reaction during the discharge process and the oxidation reaction of Li2O2 during the charge process. In this article, we report on the electrocatalytic activity of platinum, iridium, and platinum–iridium alloy in an oxygen electrode. The average crystallite size of the previous metal nanoparticles was less than 2nm, which were uniformly dispersed on the surface of chained Ketjenblack powder. Both chronoamperometry analysis and cell testing showed that Pt–Ir/C electrode exhibited superior activity and is the best electrode in this research. The discharge potentials for all three catalysts are similar, ∼2.81V vs. Li/Li+, and the discharge overpotential (∼0.15V) is very low. The charge overpotential for Pt–Ir/C composites was around 0.6V.