ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT Influence of local carbon fibre orientation on the water transport in the gas diffusion layer of polymer electrolyte membrane fuel cells Authors Henning Markötter a,b, *, Katja Dittmann b , Jan Haußmann c , Robert Alink d , Dietmar Gerteisen d , Heinrich Riesemeier e , Joachim Scholta c , John Banhart a,b , Ingo Manke b Author affiliations a) Technische Universität Berlin (TUB), Straße des 17. Juni 135, 10623 Berlin, Germany b) Helmholtz-Zentrum Berlin (HZB), Hahn-Meitner-Platz 1, 14109 Berlin, Germany c) Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden Württemberg (ZSW), Helmholtzstraße 8, 89081 Ulm, Germany d) Fraunhofer Institut für Solare Energiesysteme (ISE), Heidenhofstr. 2, 79110 Freiburg, Germany e) Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany *corresponding author present/permanent address: Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany phone: +49 30 8062 42826 henning.markoetter@helmholtz-berlin.de Keywords (max. 6 keywords) Polymer electrolyte membrane fuel cell, gas diffusion layer, perforation, liquid water transport, local fibre structure, radiography combined with tomography Abstract We used synchrotron X-ray imaging to investigate the influence of local fibre structures of gas diffusion layers (GDL) in polymer electrolyte membrane fuel cells on the transport of water. Two different measurement techniques, namely in-situ radiography and ex-situ tomography, were combined to reveal the structure-