Reduction behaviors of NiO-modified large surface area CeO2-ZrO2, solid solutions were examined by the temperature-programmed reduction technique. NiO modification of the CeO2ZrO2 solid solution lowered the reduction temperature of the solid solution. At the reduction stage of the CeO2-ZrO2 solid solution, NiO was the sole species observed by XRD. Therefore, NiO particles apparently facilitated the reduction of the solid solution, lowering its reduction temperature. The activity of the NiO/CeO2-ZrO2 catalysts for partial oxidation of methane to H-2 and CO increased with an increase of oxygen storage capacity of the CeO2-ZrO2 solid solutions. The NiO particles having strong interaction with the support showed high stability for partial oxidation of methane, while the NiO particles having weak interaction produced a large amount of coke (carbon nanotubes).