The three dimensional water distribution and transport pathways in gas diffusion layers (GDL) of a polymer electrolyte membrane fuel cell (PEM FC) are analysed at various operating conditions. The method of quasi in-situ Xray tomography is used for a three dimensional visualization of the water distribution and the GDL structure. Based on the results of dynamic radiographic measurements water
... [Show full abstract] transport pathways are located and subsequently investigated in detail by means of tomography. The combination of 2D and 3D techniques allows for an identification of 3D transport pathways through the GDL.