Abstract: Solid oxide electrolysis cells (SOECs) can effectively convert CO₂ into high value-added CO fuel. In this paper, Sc-doped Sr₂Fe_1.5Mo_0.3Sc_0.2O_6−δ (SFMSc) perovskite oxide material is synthesized via solid-phase method as the cathode for CO₂ electrolysis by SOECs. XRD confirms that SFMSc exhibits a stable cubic phase crystal structure. The experimental results of TPD, TG, EPR, CO₂-TPD further demonstrate that Sc-doping increases the concentration of oxygen vacancy in the material and the chemical adsorption capacity of CO₂ molecules. Electrochemical tests reveal that SFMSc single cell achieves a current density of 2.26 A/cm² and a lower polarization impedance of 0.32 Ω·cm² at 800 °C under the applied voltage of 1.8 V. And no significant performance attenuation or carbon deposition is observed after 80 h continuous long-term stability test. This study provides a favorable support for the development of SOEC cathode materials with good electro-catalytic performance and stability.