The regulation of mass transport through anode diffusion layer is one of the major issue of direct methanol fuel cell. In fact it is critical to maintain an adequate methanol concentration in the anode electrode such that both the rate of methanol crossover and the mass transport loss can be minimized. In the present work the effect of anode micro-porous layer on system operation is investigated both experimentally and theoretically. The developed 2D two-phase isothermal model is validated with respect to three different typologies of measure at the same time, increasing results reliability. Model simulations highlight that anode micro-porous layer can cause an inversion of water diffusion flux through the membrane and enhances methanol gas diffusion mechanism, reducing methanol crossover. Finally the developed model is used as a tool to design an optimized anode diffusion layer. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.