A mesopore sized YSZ-SiO2 ceramic hollow fibre membrane has been fabricated using a novel phase transition technique. The N-2 or H-2 single-gas permeation under relatively high pressure gradients reveals that the YSZ-SiO2 membrane is gas permeable, and the mean pore diameter of the membrane is less than four nanometers. Examination of the microstructure of the membrane shows that the YSZ-SiO2 ceramic is well sintered and is free of packing-pores. By analyzing the phase transition of the SiO2 and the microstructure of the membrane, it is believed that the pores in the membrane for the gas permeation were created by the beta -> alpha transition of cristobalite. (C) 2009 Elsevier B.V. All rights reserved.