Understanding the migration of Ni/NiO in nickel yttria-stabilized zirconia (Ni-YSZ) can potentially help to design a better solid oxide fuel cell (SOFC) anode. We observed that an extensive hydrogen reduction and methane steam reforming of Ni-YSZ caused bulk migration of Ni/NiO to at least similar to 5 mu m deeper from the Ni-YSZ surface. No significant bulk migration effects were detected after simple thermal treatments in a nonreducing/nonreforming environment. The surface analysis of a single zirconia grain in the first 10-20 nm region from the annealed, hydrogen-reduced, and methane-steam-reformed Ni-YSZ shows a Ni-enriched surface supporting earlier claims of Ni exsolution. A three-dimensional electron backscattered diffraction analysis of the thermally treated sample before exposing it to reducing and reforming environments indicated a mixed NiO/YSZ phase with some porosity and random grain orientation. The surface analysis and mapping were carried out using time of flight secondary-ion mass spectroscopy and Auger electron spectroscopy, whereas energy dispersive X-ray spectroscopy maps on focused ion beam sliced areas on Ni-YSZ were utilized for the bulk analysis. The results provide additional information related to complex reactions occurring in SOFCs during internal reforming conditions.