A first comparison is made of the anisotropic porosity profiles for various polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layer (GDL) materials. Microscale computed tomography (μCT) imaging is performed for two main categories of commercially available GDL materials (carbon fibre paper and felt). The methodology to analyze the through-plane porosities for various materials is presented, and conclusions are drawn about the material pore structures. This work provides insight into both the internal GDL material properties for liquid water transport and the external GDL properties for droplet transport in a PEMFC gas channel.