A combined experimental and numerical study is performed on a button-cell LNO-ITM reactor. A semiempirical model for oxygen permeation is considered, ABn model, and the values of the empirical constants are calculated based on the fitting of the available experimental data in the literature. A validation study for the present model is performed using the present experimental data. A detailed numerical study is presented on an LNO-ITM button-cell reactor under oxy-fuel combustion conditions. CH4 is used as the working fuel forming a mixture with CO2 at the permeate side inlet. The model results showed reasonable agreements under different operating conditions. The effect of reactivity in the permeate side of the membrane on oxygen permeation flux is considered. It is found that the oxygen permeation flux is increased by about 50% for the case of reacting flow as compared to the case of nonreacting flow. Distinct behavior of oxygen permeation flux values through the present button-cell ITM reactor is encountered while varying the operating conditions as compared to other reactors in the literature. This may be attributed to the complicated design of the flow path close to the membrane surface which maximizes the effects of flow momentum on the oxygen flux. (C) 2015 Elsevier Ltd. All rights reserved.