An ultrathin La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) hollow fibre membrane for enhanced oxygen permeation flux was fabricated using a wet spinning/sintering method. The membrane exhibits a highly asymmetric structure comprising of a very thin dense outer layer supported by finger-like structures that are fully open on the inner surface. Oxygen permeation measurements were conducted using sweep gas as an operating mode. Effects of operating temperatures and flow rates of the sweep gas on the oxygen permeation fluxes were investigated in details. The highest oxygen permeation flux, i.e. 0.096 cm(3)/cm(2) s (5.77 cm(3)/cm(2) min) was obtained from the ultrathin hollow fibre membrane at 1323 K (1050 degrees C) and the sweep gas flow rate of 2.42 cm(3)/s. The results indicate that the oxygen permeation flux obtained is much higher (4.9-11.2 times) than that obtained from conventional LSCF hollow fibre membranes mainly due to the reduced thickness of the membrane as well as the porous surface on the permeate side. In addition, despite a very thin dense layer, the LSCF hollow fibre membrane possessed a reasonable mechanical strength (113.22 MPa). (C) 2009 Elsevier Ltd. All rights reserved.