The influence of chromium in metal components on oxygen permeation and microstructure of BaCo0.7Fe0.2Nb0.1O3-delta(BCFNO) membrane was investigated under the condition of the oxygen-permeable membrane reactors. In the presence of chromia-forming metal components, the oxygen permeation (f)lux decreased by about 2.4% and 10% when using dry air and humidified air (4% H2O) for 100 h at 850 degrees C, respectively. In the presence of chromia-forming alloys on the permeate side, the oxygen permeation flux decreased by 7% within 100 h. Due to the deposition of volatile Cr species from chromia-forming alloys and formation of spinel phases of BaCrO4 and BaCr2O4 on the membrane surfaces, the performance of the membrane reactors deteriorated continuously as a function of time. Poisoning of chromium species is also a critical issue for the application of MIEC oxygen permeable membrane reactors. (C) 2015 Elsevier B.V. All rights reserved