Plasma modifications of catalyst supports before and after impregnation of metal precursors improve the activity, selectivity and stability of catalysts, e.g. Ni catalysts for benzene hydrogenation and Pd catalysts for selective hydrogenation of acetylene. Plasma modification of the support before impregnation is slightly more effective than the plasma modification after impregnation. However, plasma modifications after impregnation increase the stability and selectivity of catalysts more effectively. The economic benefit of much improved stability of Ni catalysts for hydrogenation of benzene and the enhanced activity and selectivity of Pd catalysts for acetylene hydrogenation, e.g., is significant. Similar benefits for various catalysts and other industrial processes via RF plasma techniques are expected.