A gas permeable, carbon based, nanocomposite membrane comprises a nanoporous carbon matrix comprising a pyrolyzed polymer, and a plurality of nanoparticles of carbon or an inorganic compound disposed in the matrix. The matrix is prepared by pyrolyzing a polymer, and nanoparticles of the particulate material are disposed in the polymer prior to pyrolysis. The particles may be disposed in a precursor of the polymer, which precursor is subsequently polymerized, or in the polymer itself.