The H2/CO2selectivity across ZIF-7 membrane prepared by in-situ growth method at 105°C synthesis temperature for 2 h, was the highest at 15.98, nearly 4 times higher than H2/CO2 Knudsens E.q. factor of 4.7. ZIF-7 membranes prepared from in-situ growth method also surprisingly performed better than ZIF-7 membranes prepared by other innovative techniques such as electro-spray deposition and secondary growth methods. (selectivity : 9.59 and 4.7, respectively) Despite lower selectivity performance than the numerically predicted results, the micro-porous ZIF-7 membrane prepared in this work demonstrated higher H2 permeability of 3770 barrer. Performance comparison between various inorganic membranes, including ZIF-7 & ZIF-8 membranes, was made and a new upper boundary for inorganic membranes was also constructed and reported.