Bifunctional Pt/Ir x (IrO2)10− x (x <10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Ir x (IrO2)10− x support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir3(IrO2)7 nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir3(IrO2)7 catalyst possesses the highest electrochemical surface area (24.74m2 g−1) and the highest activity towards oxygen reduction reaction (ORR) (21.71mAmg−1 at 0.85V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35mAmg−1 at 1.55V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.