Novel perovskite-type A-site calcium-doped Nd 1 – x Ca x BaCo 2 O 5+ δ oxides were studied in terms of oxygen electrode materials for reversible solid oxide cells (RSOCs). The electrode of x ≤ 0.2 was composed of a tetragonal perovskite structure with a P4/mmm space group. A Ca 2+ dopant was used to improve the thermal expansion coefficient (TEC), conductivity, and electrochemical properties of the NdBaCo 2 O 5+ δ oxides, with TEC and conductivity values of Nd 1 – x Ca x BaCo 2 O 5+ δ ( x = 0–0.2) of 17.5–16.2 × 10 −6 K −1 and 960.4–1068 S cm −1 , respectively. The X-ray photoelectron spectroscopy results indicated that Ca 2+ doping has a beneficial influence on the surface oxygen adsorption properties and the increase in the concentration of Co 4+ . On the basis of the first-principles density functional theory, doping with Ca 2+ leads to easier oxygen release and uptake. The area specific resistance of the x = 0.2 electrode was 0.058 Ω cm 2 at 700 °C, whereas at 800 °C, the cell using the x = 0.2 oxygen electrode exhibited a maximum power density of 740 mW cm −2 when H 2 was used as the fuel, and the current density of the electrolytic pure CO 2 at 1.5 V was 1.68 A cm −2 . These attractive electrochemical properties suggest that Ca-based doping is an effective method for developing (reversible solid oxide cell) RSOC oxygen electrodes. • The structure and properties of NCBC double perovskite oxides were studied in terms of oxygen electrodes for RSOCs. • The introduction of Ca significantly reduces the TEC and increases conductivity. • Doping with Ca 2+ leads to easier formation of oxygen vacancies at the Nd–O layer. • NCBC exhibits excellent reversibility and catalytic activity in the opposite operating mode.