In this study, flexible carbon hollow fiber membranes derived from sulfonated poly(phenylene oxide) (SPPO) as a carbon precursor were developed. We observed that a lower pyrolysis temperature (450-600 degrees C) gives more flexible carbon membranes with smaller bending radii, whereas pyrolytic membrane at 700 degrees C becomes less flexible and rather brittle due to a sintering of the carbon matrix. It was found that the thinness of the hollow fiber provides a desired flexibility to the carbon membranes. The carbon hollow fiber membrane pyrolyzed at 600 degrees C showed not only better mechanical stability but also excellent performance for gas separation such as O-2/N-2 and CO2/CH4. (C) 2010 Elsevier B.V. All rights reserved.