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The significant challenges facing the development of the cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) are the poor oxygen reduction reaction (ORR) activity as well as the CO 2 poisoning issues. Herein, an La/Nb co-doped perovskite Ba 0.9 La 0.1 Co 0.7 Fe 0.2 Nb 0.1 O 3- δ (BLCFN) has been developed as a promising cathode for IT-SOFCs. The polarization resistance of BLCFN cathode is 0.073 Ω cm2 at 700 °C air. This remarkable improved ORR activity can be attributed to the increased oxygen vacancies caused by the introduction of La3+ and Nb5+ ions. Furthermore, the collaboration introduction of La3+ and Nb5+ ions greatly reduce the alkalinity of the BLCFN electrode, bringing excellent CO 2 -tolerance for BLCFN cathode. No carbonate is yielded on the surface of the BLCFN cathode. The improvement on CO 2 -tolerance for these cathodes is largely attributed to the introduction of Nb5+ ions, which have higher acidity and more powerful M − O bond, and the introduction of La3+ can improve the ORR activity of the material on this basis. The co-doping of La/Nb elements furtherly stabilizes the lattice structure. Overall, the high ORR activity and CO 2 -tolerance of the cathode manifest a bright application prospect for BLCFN cathode in SOFCs and other membrane reactors. [Display omitted] • A more stable cubic structure is achieved by La/Nb co-doping. • La/Nb co-doping improves the oxygen reduction reaction activity. • BLCFN cathode material exhibits superior resistance towards CO 2 poisoning. • A peak power density of 812 mW cm−2 is achieved at 700 °C with BLCFN cathode. [ABSTRACT FROM AUTHOR]