Carbon molecular sieve membranes derived from cellulose-hemi cellulose have been evaluated for hydrogen separation from light hydrocarbons. Copper(II) nitrate was added to the precursor in the range of 0-6 wt%, resulting in increased hydrogen/methane permselectivity at the expense of permeability. Carbonization temperature was varied from 400 to 700 degrees C, with the best performance for membranes produced between 550 and 650 degrees C. Mixed gas tests with H-2, CO2, C-1-C-4 and N-2 showed that these membranes tolerate light hydrocarbons and separated hydrogen with a permeability of about 480 Barrer and hydrogen/methane permselectivity >1000. Hydrogen/carbon dioxide permselectivity was found to be approximately 23 at 25 degrees C. Transport was activated and an increase of 65 degrees C doubled the mixed gas hydrogen permeability. Performance was strongly influenced by exposure to air. (c) 2007 Elsevier B.V. All rights reserved.