A new method is presented for the preparation of carbon membranes having both catalytic and gas separation properties that could utilize the advantages of laminar flow and high conduction in a microchannel. The carbon membranes with highly dispersed metal were prepared by the carbonization at 500-900degreesC of polyamide acid membrane loaded with bivalent cations of Cu, Ni or Zn by ion exchange. The metal-loaded carbon membranes carbonized at 700degreesC have macropores of about 100 nm in diameter. The micropore volume of the membranes carbonized at 700degreesC was much larger than that of the carbon membranes without exchanged cations. The cations can form ionic crosslinks between two carboxyl groups and were converted to highly dispersed metal oxide or elemental metal particles during the carbonization. The particle diameter in the carbon membranes loaded with Cu, Ni and Zn had particle diameters of about 20, 25 and 100 nm, respectively, and were expected to possess high activity. Using the prepared catalytic membranes, the high hydrogen yields were obtained in methanol decomposition.