The effect of nonthermal RF plasma treatments on alumina-supported nickel. catalysts was investigated for benzene hydrogenation because of recent increased interest in using plasma techniques for catalyst development. As evidenced by the temperature-programmed reduction (TPR) results, plasma treatments, either before or after impregnation, can significantly change the structure of an Ni precursor supported on alumina and the interaction between them, though treatments after impregnation have a more prominent effect. Plasma modifications both before and after impregnation of metal precursors are effective in improving the activity and stability of Ni catalysts for benzene hydrogenation. The plasma modification before impregnation is slightly more effective for the activity enhancement than the plasma modification after impregnation. However, plasma modifications after impregnation increase the stabilities of catalysts much more than those of catalysts with plasma modifications before the impregnation. The plasma effect on the activity and stability of Ni catalysts for benzene hydrogenation is likely due to the modified metal-support interaction induced by plasmas. It is clearly demonstrated that the nonthermal RF plasma is an effective way, at room temperature, to modify and enhance Ni/Al2O3 catalysts for benzene hydrogenation.