In this paper, the impact of dead-ended anode (DEA) operation on the liquid water management of polymer electrolyte membrane fuel cells (PEMFCs) was investigated using X-ray synchrotron radiography. The fuel cell voltage and concurrent through-plane liquid water saturations in anode and cathode gas diffusion layers (GDLs) were measured during DEA and open anode operation. It was observed that DEA operation led to significant increases in liquid water content in both anode and cathode GDLs, along with fuel cell power output degradation. A strong correlation was observed between the buildup of the liquid water in the anode and the cathode, and as a result, the liquid water transport in the cathode was also significantly impacted by this DEA operation. •In situ liquid water thicknesses were measured by synchrotron X-ray radiography for a fuel cell operating in DEA.•Fuel cell voltage degradations were linked to both anode and cathode GDL flooding.•Strong correlations between anode and cathode liquid water content were observed.