A reactor using dense. mixed ion electron conducting membranes was successfully studied in the oxidative dehydrogenation of ethane to ethylene. Already bare Ba0.5Sr0.5Co0.8Fe0.2O3-delta membranes allowed reasonable operation with yields beyond state-of-the-art steam cracking. The application of a surface catalyst was found to enhance performance even further. Long term stable operation and ethylene yields of about 75% were observed when using membranes with V/MgO micron grain or Pd nano cluster modified surfaces at temperatures of 1040 or 1050 K, respectively. Being one key factor for the performance of the membrane reactor, the influence of the surface catalysts on the oxygen permeation is reported in a detailed study. Parameters for a model describing the oxygen permeation were determined. The nature of the model indicates the importance of the surface exchange for oxygen permeation, explaining in this way the observed enhancement after application of surface catalysts at the permeate side. (c) 2005 Elsevier B.V. All rights reserved.