This work shows that the gas separation performance of phenolic resin-based carbon membranes can be adjusted by controlling the pyrolysis processing variables (heat treatment temperature, heating rate, soaking time and atmosphere). A large variety of carbon membranes for gas separation have been developed by simple carbonization of a phenolic resin film deposited on a ceramic tubular support. Thus, molecular sieve carbon membranes (MSCMs) with good capabilities towards the separation Of O-2-N-2, CO2-CH4, CO2-N-2 and olefin-paraffin mixtures as well as adsorption-selective carbon membranes (ASCMs) effective in the recovery of hydrocarbons from hydrocarbon-N-2 mixtures have been obtained. (C) 2003 Elsevier B.V. All rights reserved.