Oxygen transport through SrFe1.125Co0.375Oy oxide coupled with the oxidation of CO was investigated in the temperature range of 900-850 degreesC. An oxygen flux as large as 1.3 X 10(-6) mol cm(-2) s(-1) was observed through a 1.2 mm thick membrane at 900 degreesC by exposing one side of the membrane to air and the other side to mixture of helium and carbon monoxide with P-CO at 0.16 atm. This value is two orders of magnitude higher than the value measured in the absence of CO. The oxygen permeation flux remained almost unchanged with the variation of the membrane thickness, and increased with the CO partial pressure. The flux showed a weak temperature dependence with an apparent activation energy of 28+/-3 kJ/mol. These observations all suggest that the oxygen exchange between the gas/solid interface is the rate-limiting step of the oxygen permeation process. (C) 2000 Elsevier Science B.V. All rights reserved.