This paper extensively discussed the gas permeabilities in MMM using theoretical models and the results were compared with the published experimental data. The models considered are: Maxwell model modified Maxwell model, Lewis-Nielsen model, modified Lewis-Nielsen model and Felske model. The selected models were compared based on published experimental data (168 data point) of MMMs, inorganics including zeolites NaA and NaX and neat polymer permeabilities. The results generated based on standard deviation, sigma and absolute average relative error, %AARE for the models studied show a decreasing order: Lewis-Nielsen model > Maxwell model > modified Lewis-Nielsen model> modified Maxwell model > Felske model. This indicates that the most reliable predictive model in predicting gas permeability in MMM is Felske model. (C) 2009 Elsevier B.V. All rights reserved.