A tape casting co-sintering route is described in which thin dense layers of LaSrFeCoO3 (LSFC) have been formed on planar, porous MgO substrates 100- 200 micron thick. SEM analysis of the sintered structure showed that it was possible to eliminate most of the residual porosity in the LSFC layer, but maintain a porosity between 25 and 45% in the MgO support layer. The LSFC layer dit not reveal many cracks. The overall shrinkage of the co-sintered structure was about 25%. The LSFC layer topography was smooth and uniform with a metallic-like lustre. A good correlation was obtained between the observed microstructure and the gas permeability measurements made at room temperature.