Mixed matrix membranes based on zeolite LTL dispersed in a glassy polyimide, 6FDA-6FpDA, as well as in block copolymers composed of 6FDA-6FpDA and amine-terminated polydimethylsiloxane (PDMS) were fabricated and characterized for gas transport properties. Pure gas permeability tests were performed using He, O-2, N-2, CH4 and CO2 for each membrane. Permeability was shown to increase for all gases as the siloxane content in the copolymer increased. The addition of zeolite L to the polymer matrix lowered the permeability of all gases regardless of the polymer matrix, and did not offer improvements in the ideal selectivity of any gas pair investigated. (c) 2005 Elsevier B.V. All rights reserved.