Commercial SCR catalysts used in a coal-fired power plant were regenerated by H2SO4 solution. The characterization study of the catalysts was carried out by using various analytical techniques. Major deactivating elements for the SCR catalyst were determined and the optimal condition for regeneration of the catalyst was investigated. The catalyst regenerated with 0.5 wt% H2SO4 solution showed a high catalytic activity due to an increase in the polymeric vanadates and acid sites by surface sulfates. A higher H2SO4 concentration than 2.5 wt% in the washing solution leads to a loss of active components out of the catalyst by dissolution and a dramatic decrease in the surface area.