Successfully incorporating Gd3+ ions into the A-site of BaFeO3-δ by sol-gel method, has resulted in the formation of cobalt-free GdxBa1-xFeO3-δ (x= 0.1, 0.2, 0.3, and 0.4) perovskites with a stable cubic symmetric structure. The analysis of oxygen vacancy and electrical conductivity reveals that the higher conductivity of Gd0.3Ba0.7FeO3-δ (GBF0.3) promotes the oxygen reduction reaction activity while ensuring enough oxygen vacancy, resulting in the higher electrochemical performance. At 800°C, the polarization resistance of GBF0.3 symmetrical cell and the maximum power density of the GBF0.3 single cell are 0.019 Ω cm² and 0.99 W cm-2, respectively. Furthermore, the single cell can operate stably for 117 hours under 1.2 A cm-2. Therefore, it holds great promise as a novel cathode candidate for solid oxide fuel cells (SOFCs).