Hollow-fiber membranes of mixed conducting perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-delta were prepared using a sequence of extrusion, gelation, and sintering steps. For this purpose, a finely divided mixture of the component oxides was prepared by the modified Pechini technique and suspended in a polymer solution. The suspension was extruded through a spinneret and gelled in water. The resulting fiber was first heated at 800 degrees C to remove the polymer and then at 1100 degrees C to form the perovskite and simultaneously sinter the particles to a gastight membrane. The fibers were characterized by scanning electron microscopy and tested for air separation at ambient pressure and temperature between 700 and 950 degrees C. The maximum oxygen flux measured was 3.9 mlJmin/cm(2) at 950 degrees C and 0.022 atm of average permeate oxygen partial pressure.