Soluble metal phthalocyanines, e.g, PcFe(OCH2CF3)(4) form supramolecular complexes with a cyanoethylated hydroxypropylcellulose polymer (AHC) with nitrile groups on flexible spacers. Composite membranes made from these complexes enrich O-2 or CO2 from a mixture with N-2 or CH4, respectively. The complexation is concluded from spectroscopic observations and from differences in membrane properties, The surface structure of the membranes was investigated by AFM. Optimal selectivity and permeability were found with membranes containing phthalocyanines with bulky substituents on the macrocycle and metal ions, which are able to coordinate with the nitrile groups of the polymer. Some fluorinated substituents gave high permeate fluxes. Optimal selectivity values found were 3.5 for alpha(O2/N2) and 18 for alpha(CO2/N2). For the feed CH4/CO2 swelling effects were observed.