Mixed matrix membranes (MMMs) prepared with 6FDA-DAM polymer using ordered mesoporous silica MCM-41 spheres (MSSs), Grignard surface functionalized MSSs (Mg-MSSs) and hollow zeolite spheres are studied to evaluate the effects of surface modification on performance. Performance near or above the so-called permeability-selectivity trade-off curve was achieved for the H-2/CH4, CO2/N-2, CO2/CH4, and O-2/N-2 systems. Two loadings (8 wt % and 16 wt %) of MSSs were tested using both constant volume and Wicke-Kallenbach sweep gas permeation systems. Besides single gas H-2, CO2, O-2, N-2, and CH4 tests, mixed gas (50/50 vol %) selectivities were obtained for H-2/CH4, CO2/N-2, CO2/CH4, and O-2/N-2 and found to show enhancements vs. single gases for CO2 including cases. Mg-MSS/6FDA-DAM was the best performing MMM with H-2/CH4, CO2/N-2, CO2/CH4, and O-2/N-2 separation selectivities of 21.8 (794 Barrer of H-2), 24.4 (1214 Barrer of CO2), 31.5 (1245 Barrer of CO2), and 4.3 (178 Barrer of O-2), respectively. (c) 2015 American Institute of Chemical Engineers AIChE J, 61: 4481-4490, 2015