Small scale passive self-breathing micro fuel cells are an interesting alternative approach to power small integrated portable systems. The water management of these cells is greatly affected by the cell design especially at the cathode side. Different cathodic current collector designs with different opening ratios are studied considering the impact onto the water distribution by using in situ high resolution neutron imaging. The impact of pulsed and constant load operation is analyzed as well as the impact of different environmental conditions. Several key observations could be made concerning water management in such cells, including the absence of water accumulation in the anode channels as well as the absence of excessive flooding of the cathode gas diffusion layer (GDL), even in designs implying lateral transport of liquid water over relatively large distances (up to 5 mm). (C) 2012 Elsevier Ltd. All rights reserved.