A potentionstatic step technique was used to measure oxygen transport in the mixed-conducting perovskite SrCo1-xFexO3-delta where x = 0.2, 0.5 and 0.8. A solid state sealed electrochemical cell configuration was employed for this purpose featuring a single crystal yttria-stabilized zirconia solid electrolyte. The chemical diffusion coefficient of oxygen was found to be fast but highly thermally activated. At 850 degrees C, the chemical diffusion coefficient for oxygen was in the range 10(-7)-10(-6) cm(2)/s With the SrCo0.5Fe0.5O3-delta composition exhibiting the higher value. Such rapid rate of oxygen transport makes this material attractive for oxygen selective membranes for high temperature gas separation applications.