Ni and NiO based oxygen carrier particles are developed for chemical-looping combustion,, in which fuel is oxidized by metallic oxide medium in a reduction reactor and reduced metal is oxidized by air in oxidation reactor. This system may yield great advantage of savings of energy and suppressing the effect on environment. Two kinds of materials, Ni and NiO base particles, are examined from the viewpoint of reaction kinetics and carbon deposition. The purpose of this study is to find suitable materials that may suppress carbon deposition (e.g. effects of solid composition and base material), to clarify appropriate reaction conditions to avoid carbon deposition (e.g. temperature and maximum carbon deposition free conversion) and to interpret the effect of temperature on reaction rate.