Different Sigma-1 zeolite loaded Matrimid (R) 5218 mixed matrix membranes (MMMs) were prepared by solution casting and CO2/CH4 gas separation experiments were performed. Also, the Maxwell model was employed to predict through the CO2/CH4 permeability prediction Sigma-1 -Matrimid (R) 5218 MMMs. Without considering the polymer chain rigidification and the partial pore blockage effects on the Maxwell model, the AARE (average absolute relative error) values were high, i.e. for CO2 permeability as 14.2%, for CH4 permeability as 65.9% and for selectivity prediction as 30.5%. However, the AARE values were reduced after including the polymer chain rigidification and the partial pore blockage effects into the Maxwell model by introducing two parameters, beta and alpha, into the model so that the AARE value for CO2 permeability prediction was 1.6%, for CH4 permeability prediction was 14.5% and for selectivity prediction was 15.7%. (C) 2014 Elsevier B.V. All rights reserved.