SrFe1-xCoxO3-z (0 less than or equal to x less than or equal to 1, z similar to 0.1) of the cubic perovskite type was prepared by treating mixtures of grossly oxygen-deficient samples obtained at room temperature, using an electrochemical oxidation technique. The ferromagnetic Curie temperature has been found to be raised above 300 K for 0.4 less than or equal to x less than or equal to 1.0 (340 K at x = 0.4) by the electrochemical oxidation method. Only a few hundred mV of electrode potential has relatively more oxidation power than a considerably high oxygen pressure, however, the lack of stability after electrolysis isa weak point.