A crack-free supported mixed-conducting membrane (composite 60 wt.%SrCo0.4Fe0.5Zr0.1O3-delta/40 wt.%MgO, SCFZ-0.4MgO) was successfully prepared by the dry-pressing technique directly on a support with the different composition (composite 60 wt.%MgO/40 wt.%SrCo0.4Fe0.5Zr0.1O3-delta, MgO-0.4SCFZ), followed by sintering. The match of thermal performances between the membrane and the support was realized by incorporating the support material,(MgO) into the membrane (SCFZ) and simultaneously merging the membrane material (SCFZ) into the support (MgO). SEM and the nitrogen gas-tight test demonstrated that the surface of the supported membrane was dense and crack-free. XRD patterns showed that SCFZ was chemically compatible with MgO. The oxygen flux of the supported membrane with a dense layer of 200 mu m and a support layer of 1.0 mm was about 9-11 times that of the 1.2 mm symmetric SCFZ-0.4MgO membrane. (c) 2006 Elsevier B.V. All rights reserved.