Zeolitic imidazolate framework ZIF-11 particles were prepared and mixed with Matrimid (R) 5218 polyimide, from 0 to 40 wt. % loadings. The ZIF-11 particles and the Matrimid (R) 5218 polyimide matrix were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-Ray diffraction (XRD), infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) techniques. Surface and cross-sectional scanning electron microscopy images of the mixed matrix membranes (MMMs) were taken to examine the dispersion of particles in the polymer matrix. No visible agglomeration between ZIF-11 particles and the polymer matrix was spotted, even at 40 wt. % ZIF-11 loading. Mixed matrix membranes were described by the measured permeabilities of H-2, CO2 and CH4 gases. Ideal gas selectivities were determined. Permeability of all gases increased with increasing ZIF-11 percentages. The permeabilities for all gases decreased at 40 wt. % loading, and the CO2/CH4, and H-2/CH4 selectivities were increased. (c) 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.