JDF-L1 is a microporous titanosilicate exhibiting a layer structure with pore size of about 3 angstrom. It is consequently an attractive material to separate H(2)-containing mixtures. This is the reason why JDF-L1 after disaggregation by means of hexadecyltrimethylammonium surfactant, has been combined with a carboxyl group containing copolyimide (6FDA-4MPD/6FDA-DABA 4:1) to produce mixed matrix membranes, which were applied to the separation of H(2)/CH(4) and O(2)/N(2) mixtures. Additionally, due to the sheet growth habit of JDF-L1 crystals, a preferential horizontal orientation of the JDF-L1 filler particles dispersed into the polymer was expected. This preferential orientation, which was achieved when the polymer solution concentration used during the membrane casting process was relatively low, has been studied by optical and electronic microscopy. X-ray diffraction and polarized Raman spectroscopy. A quantitative analysis was carried out applying Cussler's model for mixed matrix membranes with oriented flakes. (C) 2011 Elsevier B.V. All rights reserved.