Cathodic overpotentials of Ln(0.6)Sr(0.4)MnO(3) (Ln = La, Pr, Nd, Sm, Gd, Yb, and Y) were studied for a new cathode of solid oxide fuel cell (SOFC). Cathodic overpotentials as well as the electrical conductivity strongly depended on the rare earth cations used for the A sites of perovskite oxide. Strontium doped PrMnO3 exhibited the highest electrical conductivity among the examined perovskite oxide containing Mn for B sites. Moreover, overpotentials of Sr-doped PrMnO3 cathode maintained low values in spite of decreasing the operating temperature. Consequently, almost the same power density of SOFC with La0.6Sr0.4MnO3 cathode can be obtained at about 100 K lower operating temperature by using Sr-doped PrMnO3 as the cathode. The overpotentials and electrical conductivity decreased and increased with increasing the amount of Sr dopant in PrMnO3, respectively, and the lowest overpotential was attained at x = 0.4 in Pr1-xSrxMnO3. Comparing with La0.6Sr0.4MnO3 oxide, the reactivity of Pr0.6Sr0.4MnO3 with Y2O3-stabilized ZrO2 is much less than that of La0.6Sr0.4MnO3 and furthermore, the matching of thermal expansion of Pr0.6Sr0.4MnO3 with Y2O3-ZrO2 was satisfactorily high. Therefore, perovskite oxide of Pr0.6Sr0.4MnO3 has a great possibility of the cathode materials for decreasing the operating temperature of solid oxide fuel cells.