Metal organic framework (MOF) membranes have attracted significant attentions in recent years because of their potentials in gas and liquid separations and other applications such as catalysis and chemical sensors, etc. More than half of the MOF membrane publications up to date are related to ZIF-8 system, because of its easy synthesis, relatively high stability, and excellent gas separation performance, which allows many novel ideas to be easily implemented. Extensive studies have shown that ZIF-8 membranes hold great potentials in gas separations, but may face great challenges in liquid separations mainly because of their poor stability. This is also a common observation for other MOF membranes. As such, in this article we use ZIF-8 membrane as a prototype and focus on its development in gas separations for the discussions of the most concerned issues related to membrane commercialization including membrane synthesis, separation performance, stability, process reproducibility, and finally on the opportunities and challenges that MOF membranes may face in industrial applications.