Three cobalt Schiff-base complexes were synthesized and added into poly(dimethylsiloxane) (PDMS) and ethyl cellulose (EC) membranes as oxygen carrier. The influences of oxygen carrier concentration and temperature on the gas permeability and selectivity of the membranes were studied and the effects of oxygen carrier concentration on the oxygen facilitated transport, on the polymer chain flexibility as well as on the free volume in the membranes were discussed.