Mixed matrix membranes (MMMs) containing three different metal organic frameworks (MOFs) (Cu3BTC2, FeBTC and MIL-53 (Al)) as filler in P84 were prepared and characterized in terms of ethylene/ethane separating ability. SEM, TGA and DSC suggest the absence of non-selective voids in the Cu3BTC2 and FeBTC MMMs. Gas permeation experiments confirmed this, and showed an increase in ethylene/ethane selectivity of 73% to a value of 7.1, while ethylene permeability remained constant at 17 x 10(-18) mol m/(m(2) s Pa) with addition of 20 wt% Cu3BTC2. Addition of 20 wt% FeBTC showed a reduced permeability, caused by the formation of a denser intermediate layer, and no significant change in selectivity. Addition of MIL-53 led to increased permeabilities and no change in selectivity, which is probably the result of the formation of non-selective voids or the absence of inherent selectivity of MIL-53. (C) 2012 Elsevier B.V. All rights reserved.