Membrane-based gas separations are becoming relevant. Ordered mesoporous silicas have uniform pore channels with a mesopore range. The mesopores are advantageous for rapid diffusion of target molecules, can be modified in a variety of ways, allowing for separation applications. We first describe the technologically scalable fabrication based upon mesoporous silica membranes on polymeric hollow fibers. Furthermore, we modify the mesopores using amine-containing polysilsesquioxane molecules. The resulting modified membranes exhibit promising permeability and selectivity in separation of CO2 from N2 or CH4. Also, the CO2 and N2 transport properties of aziridine-functionalized mesoporous silica membranes are investigated. The hyperbranched aminosilica membrane shows bi-functional gas transport property regarding humidity of gas streams.