The microstructural characteristics of the anode microporous layer (MPL) can significantly affect the mass transport in direct methanol fuel cells by influencing the methanol delivery and CO2 removal processes. The hydrophilic-hydrophobic balance and pore structure of the flow path were established by optimizing the content of polytetrafluoroethylene (PTFE) in the anode MPL. An empirical model was developed to design and optimize the anode MPL to achieve better mass transport and cell performance. From the simulated and experimental results, increasing the content of PTFE enhanced the CO2 removal ability in the anode MPL, thereby alleviating CO2 blockage in the anode catalyst layer, whereas the narrowed flow path hindered methanol delivery in the anode MPL. A good balance between methanol delivery and CO2 removal in terms of mass transport was achieved when the PTFE content was adjusted to 15 wt %, leading to the best cell performance. (c) 2018 American Institute of Chemical Engineers AIChE J, 64: 3519-3528, 2018