Liquid water transport through gas diffusion layers (GDLs) with different thicknesses and different amounts of polytetrafluoroethylene (PTFE) is studied by taking an ex-situ approach. Droplet static contact angles on GDLs were also measured. Using a constant flow syringe pump, liquid water was introduced to the surface of GDL sample and the breakthrough pressure at which liquid water passes through the GDL and forms droplet on the other side of the GDL was measured by a differential pressure transducer. Liquid water can pass through the pores when its pressure exceeds the capillary pressure. It was observed that the breakthrough pressure increases with GDL thickness. Also, applying some amount of PTFE to an untreated GDL was observed to significantly increase the breakthrough pressure while more amount of PTFE within the GDL had negligible effect on liquid water breakthrough pressure. Using measured breakthrough pressures and contact angles, maximum pore diameter of GDLs were calculated based on the GDL’s single layer model.

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