Apart from conventional composite materials, in situ exsolution for constructing the heterostructure is one of the most effective strategies to design the high-performance electro-catalysts. Herein we report a novel heterostructured simple perovskite nanorod-decorated A site-deficient double perovskite PrBa0.94Co2O5+delta (SPN-APBC) cathode, synthesized by an in situ exsolving process from A site-deficient double perovskite PrBa0.94CO2O5+delta (A-PBC). The results demonstrate a highly electro-catalytic activity of the SPN-A-PBC cathode toward oxygen reduction reaction (ORR) for intermediate-temperature solid oxide fuel cells (IT-SOFCs), achieving a very low and stable polarization resistance of similar to 0.025 Omega cm(2) at 700 degrees C in air. The anode-supported single cell with this heterostructured cathode delivers a maximum power density of 1.1 W cm(-2) at 700 degrees C and a superior steady operation over 120 h at a loading voltage of 0.6 V. Furthermore, the SPN-A-PBC electrode exhibits a good tolerance to CO2. When tested in air with 6 vol% CO2 at 700 degrees C, the SPN-A-PBC electrode still maintains a stable polarization resistance of similar to 0.078 0 cm(2). The unique catalytic activity of the SPN-A-PBC cathode for ORR may be attributed to extended active sites, abundant interface defects, enhanced redox property and oxygen mobility. The fast ORR kinetics and excellent durability in air with CO2 highlight the potential of SPN-A-PBC as a potential functional material in the energy conversion devices.