Asymmetric polyethersulfone (PES) micro-porous flat sheet membranes were prepared by the phase inversion method (PIM) and used as the support. PES-PDMS composite membranes were fabricated with coating polydimethylsiloxane on the surface of PES membrane. The FluidMAG-PAD was coated on PES and PES-PDMS membrane to prepare super-paramagnetic membranes for separation of oxygen from nitrogen. Permeance and O-2/N-2 selectivity were evaluated in the absence or presence of external magnetic field. In the absence of external magnetic field, the super-paramagnetic polymer provides larger surface area leading to extended sites for oxygen adsorption. In the presence of magnetic field, the super-paramagnetic particles obtained magnetic property leading to a pronounced interaction with oxygen resulting in elevated selectivity and permeability. Copyright (C) 2011 John Wiley & Sons, Ltd.