A new mass transport model named modified binary friction model (MBFM) is proposed. The new mass transport model is based on the previously developed binary friction model (BFM) and is capable of predicting mass transport in viscous and transitional Knudsen regimes. Macro homogeneous mass transport models used in porous media are reviewed. The shortcomings of each model are discussed, and a comparison of the new mass transport model with existing models such as Fick's, dusty gas model and BFM is presented. It is found that the choice of transport model can significantly impact the predictions of mass transport. The transport predictions of the new model are significantly different compared to existing models for flow in Knudsen region and for mixtures containing gases with large difference in molecular weights. (c) 2012 Elsevier Ltd. All rights reserved.