To study the reaction kinetics at the anode of solid-oxide fuel cells, a nickel stripe pattern was prepared on the surface of yttria-stabilized zirconia (YSZ) [8 mole percent (m/o) Y2O3-doped ZrO2] by an ionized cluster beam (ICB) method and photolithography Due to grain growth of nickel film at high temperatures, the minimum possible width of the stripes was found to be ca. 5 mum. By impedance measurements in H-2-H2O atmospheres at 700 to 850-degrees-C, it was shown that the reaction proceeds through the triple-phase boundary (TPB) of H-2-H2O/Ni/YSZ and the mechanism of the rate-determining reaction is different from that at the TPB of H-2-H2O/Pt/YSZ. The former takes place on the nickel surface close to the TPB, while the latter just across the TPB. The reaction rate for a unit length of the TPB of H-2-H2O/Ni/YSZ was slower than that of H-2-H2O/Pt/YSZ by about one order of magnitude.