LaBaCo_2−xMo_xO_5+δ (LBCMx, x = 0–0.08) cathodes synthesized by a sol-gel method were evaluated for intermediate-temperature solid oxide fuel cells. The limit of the solid solubility of Mo in LBCMx was lower than 0.08. As the content of Mo increased gradually from 0 to 0.06, the thermal expansion coefficient decreased from 20.87 × 10⁻⁶ K⁻¹ to 18.47 × 10⁻⁶ K⁻¹. The introduction of Mo could increase the conductivity of LBCMx, which varied from 464 S cm⁻¹ to 621 S cm⁻¹ at 800 °C. The polarization resistance of the optimal cathode LBCM0.04 in air at 800 °C was 0.036 Ω cm², reduced by a factor of 1.67 when compared with the undoped Mo cathode. The corresponding maximum power density of a single cell based on a YSZ electrolyte improved from 165 mW cm⁻² to 248 mW cm⁻² at 800 °C.