Double perovskite SmBa0.5Sr0.5Co2O5+δ(70%)+Ce0.8Sm0.2O1.9(30%) as SBSC70+SDC30 cathode was fabricated using solid-state reaction technique and investigated as cathode material for solid oxide fuel cells operating at intermediate temperature (IT-SOFC). This work aims to determine the effect of SDC electrolyte doping into double perovskite cathodes on SOFC performance. LS-POP carried out particle size distribution analysis, and the equipment operates on a light source (HE-Ne laser) basis. XRD was used to determine the structure of the cathode powder, and SEM was used to analyze the microstructure morphology. Symmetrical cells were tested using a potentiostat Voltalab PGZ 301. The distribution of particle size for the SBSC70+SDC30 cathode was in the range of 1.41-2.03 µm. The polarization resistance (Rp) value of SBSC70+SDC30 cathode decreases with increasing temperature from 1.22 cm2 at 600°C to 0.21 cm2 at 800°C. The SBSC70+SDC30 activation energy (Ea) for Rp was 117. 3 kJ mol−1. From the overall results, double perovskite SBSC70+SDC30 cathode has potential as a cathode of medium temperature SOFC cells.