A variant of tape casting, involving phase inversion, was explored for the preparation of supported ceramic oxygen separation membranes in one step. A slurry of Zr0.84Y0.16O1.92 (YSZ) andLa0.8Sr0.2MnO3 δ (LSM) powders in a N-methyl-2-pyrrolidone solution of polyethersulfone was tape cast, and immersed in water bath for solidification into a green tape. After sintering at 1320 1C a ceramic membrane was obtained with a total porosity of 35%, consisting of a porous layer with thickness 0.85 mm on a gas-tight top layer with thickness 0.15mm. An oxygen permeation flux of 1.90 x 10- 3 mol m -2 s -1 was observed at 900 1C by exposing the porous side of the membrane to air and the other side to helium. A supported membrane with the identical YSZ/LSM ratio, made by sequential two-step tape casting, with graphite as pore former, showed a flux of 3.31 x 10- 4 mol m- 2 s -1. The difference in oxygen flux between the two membranes is attributed to the difference in resistance towards gas transport in the support layer. It is concluded that the phase inversion tape casting is a simple and effective method for preparation of supported oxygen separation membranes.