Oxygen ion conducting Ba0.5Sr0.5Co0.8Fe0.2O3-delta hollow fiber membranes with o.d. 1. 15 mm and i.d. 0.71 mm were fabricated using a sequence of extrusion, gelation, coating and sintering steps. The starting ceramic powder was synthesized by combined EDTA-citrate complexing followed by thermal treatment at 900degreesC. The powder was then dispersed in a polymer solution, and extruded through a spinerette. After gelation, an additional thin coating of the ceramic powder was applied on the fiber, and sintering was carried out at 1190degreesC to obtain the final ceramic membrane. The fibers were characterized by SEM, and tested for air separation at ambient pressure and at temperatures between 700 and 950degreesC. The maximum oxygen flux measured was 5.1 mL/min/cm(2) at 950degreesC. (C) 2004 Elsevier B.V. All rights reserved.