Poly(2,6-dimethyl-1,4-phenylene oxide) composite membrane containing the different amount of nano-sized magnetic iron oxide (magnetite) was used in gas separation (N-2/O-2) experiments and vapour permeation (ethanol/water) studies. Presence of the magnetic particles additive has an impact on the separation properties of the polymer matrix. Using this type of membranes in separation of gaseous mixtures restrains permeation of paramagnetic constituent and promotes diffusivity of the diamagnetic component. Diffusion coefficient of nitrogen increased from 8.66 x 10(-4) to 42.00 x 10(-4) cm(2) s(-1) respectively for pure PPO membrane and loaded with 10 w/w% of Fe3O4. In case of the vapour permeation studies, increase both flux and diffusivity of less polar component (ethanol) is observed. Flux changed from 1.07 x 10(-12) to 53.2 x 10(-12) cm(3) (STP) cm(-2) s(-1) and diffusion coefficient raised from 2.01 x 10(-10) to 84.2 x 10(-10) cm(2) s(-1) respectively for pure PPO membrane and loaded with 10 w/w% of Fe3O4. (c) 2013 Elsevier B.V. All rights reserved.