A catalyst and a method for selectively reducing nitrogen oxides with ammonia are provided. The catalyst includes a first component of copper, chromium, cobalt, nickel, manganese, iron, niobium, or mixtures thereof, a second component of cerium, a lanthanide, a mixture of lanthanides, or mixtures thereof, and a zeolite. The catalyst may also include strontium as an additional second component. The catalyst and the method may have special application to selective reduction of nitrogen oxides in exhaust gas from diesel vehicles, although the catalyst and the method have broad application to a wide range of gas streams that contain nitrogen oxides.