The authors report on in situ investigations of liquid water evolution and transport in an undisturbed operating fuel cell at the microscopic level. Synchrotron x-ray radiography enhances the spatial resolution by two orders of magnitude compared to the state-of-the-art techniques in this field. The primary spots of liquid water formation, their growth, and transport inside the porous gas diffusion material were analyzed; correlations between operating conditions and the dynamics of droplet formation are described. Previous findings from modeling and simulation approaches are confirmed and the applicability for the description of in situ processes of a recently proposed model has been proven.