Novel ordered mesoporous COK-12 type silica particles were used as fillers in polyimide (Matrimid) based mixed-matrix membranes (MMMs). The highly ordered 2D hexagonal structured filler materials with short and straight pores were synthesized at room temperature under quasi-neutral pH. The gas permeation and SEM results of the MMMs confirmed a homogenous filler dispersion and defect free synthesis of membranes. The presence of large mesopores in the fillers leading to faster diffusion of penetrant gas resulted in higher gas permeabilities in comparison to pristine Matrimid membrane. The potential of the membrane under mixed-gas conditions and different operating temperatures was also evaluated. The membranes showed decreasing trend of activation energy of permeation with the addition of filler. The ease of synthesis, highly ordered structure with short and straight pore channels and improved gas permeation properties makes COM-12a promising filler for industrial gas separations. (C) 2015 Elsevier B.V. All rights reserved.