Cathodic performance of double perovskite oxide of PrBaCo2O5as an active catalyst for SOFC was investigated. Because delamination of PrBaCo2O5cathode is easily occurred by larger thermal expansion coefficient, mixing effects of PrBaCo2O5with another perovskite oxide were investigated using a LaGaO3-based electrolyte. Among the oxides mixed with PrBaCo2O5(PBCO), it was found that mixing Sm0.5Sr0.5CoO3(SSC) with PBCO shows the smallest cathodic overpotential and the most suitable for increase in cathodic activity. Increase in cathodic performance can be assigned to the high activity of oxygen dissociation on SSC and the fast oxide ion diffusivity in PBCO. Therefore, composite oxide of PBCO with SSC is highly active as cathode for SOFC at intermediate temperature.