Mixed matrix membrane (MMM) is a new class of membrane materials that offers the significant potential in advancing the current membrane-based separation technology. As an attractive material that demonstrates outstanding separation properties, MMM has been the subject of worldwide academic studies conducted by many researchers especially those related to membrane technology. The past decades have witnessed substantial progress and exciting breakthroughs in both the fundamental and application aspect of MMM in various forms of separation, particularly in gas separation. These emerging materials for separation have been traditionally accomplished by incorporating conventional inorganic fillers such as zeolite, carbon molecular sieve and silica nanoparticles in a polymer matrix. The recent advances have shifted towards the introduction of new and novel materials namely carbon nanotubes, metal organic framework and clay layered silicate as potential fillers in the polymer matrix. The successful implementation of MMM depends greatly on the polymer matrix selection, the inorganic filler as well as the interaction between the two phases. The selection of suitable types of inorganic filler, the surface modification, and the performance of the resulted MMM membranes were discussed and represented the major contribution in this review. The recent efforts to tackle the underlying problems and the effects of various kinds of modification that would eventually heighten the performance of membrane applications in gas separations were discussed. Better understanding on the improvement and optimization of MMM process was provided by considering the possible solutions to overcome the problems encountered during MMM preparation. This hybrid system holds significant potential and great promise for further investigations, development and applications. The future direction and perspective in MMM research for gas separation was also briefly outlined to further advance the materials for MMM in gas separation. (C) 2011 Elsevier B.V. All rights reserved.