It is often difficult to fully resolve non-destructively both liquid water and solid structure within an operating fuel cell. Both neutrons and X-rays offer non-destructive probes to understand internal structure of objects of interest. By combining these two probes it is possible to obtain three-dimensional information on liquid water distribution and its interaction with the material structure and interfaces. The NIST neutron imaging facility offers the ability to perform simultaneous neutron and X-ray tomography by orienting a micro-focus X-ray tube orthogonal to the neutron beam. A small, 0.36 cm², fuel cell was developed specifically to facilitate simultaneous neutron and X-ray imaging and was operated at high flow rates to avoid water slug formation in the gas channels. The presentation will describe initial results and ongoing efforts in simultaneous tomography of fuel cells to further understanding of interfacial effects and overall water distribution. Shown in the figure are three-dimensional volume renderings of the composite neutron and X-ray tomography reconstructions giving water distribution with respect to fuel cell hardware and material interfaces. This work was partially supported by GM through an Academic Partnership Single Project Agreement with Rochester Institute of Technology.