Asymmetric mixed-matrix membranes (MMMs) were prepared via phase inversion from Matrimid (R) or Matrimid (R)/Polysulphone blends containing a crystalline metal organic framework (MOF [Cu-3(BTC)(2)]) to improve the membrane gas separation performance Physical properties of the synthesized MOF and the membrane (film density, T-g, d-spacing) were analyzed The distribution of MOF embedded in the polymer was studied with SEM Improvement in thermal and mechanical properties of membranes with increasing [Cu-3(BTC)(2)] loadings, as well as increasing CO2/CH4 and CO2/N-2 selectivity and permeance of the silicone sealed membranes suggests defect-free membranes with good compatibility at the filler/polymer interface Also, relative permeance was in accordance with the Maxwell model for porous materials (C) 2010 Elsevier B.V. All rights reserved