Abstract: Reversible solid oxide cell (RSOC) is a clean and efficient electrochemical conversion and storage devices. Due to the Sr segregation in the now available perovskite oxygen electrodes, new requirements are put forward for the durability of oxygen electrodes. Y_0.08Zr_0.92O_2-δ/Er_0.4Bi_1.6O₃ (YSZ/ESB) composite electrolyte and Ca₃Co₄O_9+δ (CCO) oxygen electrode were prepared by solution impregnation method in this paper. The polarization resistance of CCO oxygen electrode at 800°C was 0.45 Ω·cm². The oxygen electrode showed superior durability in the process of alternating anodic and cathodic polarization for 100 h. Anodic and cathodic polarization displayed opposite influence mechanisms on the electrode performance. The degradation induced in the electrolysis mode can be eliminated by reversibly cycling between electrolysis and fuel-cell modes. The Ni-YSZ/YSZ/ESB/CCO single cell obtained a maximum power density of 722 mW·cm⁻² at 800℃. The electrolysis current density at 1.5 V was 1204 mA·cm⁻², which corresponded to the hydrogen production rate of 503.3 mL·cm⁻²·h⁻¹. Results showed that CCO with good reversible polarization performance and long-term stability achieved a high energy conversion rate.