The present invention entails a method of removing ammonia from a gas stream. The method entails irradiating the gas stream with light in the spectral range of 200 350 nanometers and disassociating hydrogen free radicals from ammonia to form NH.sub.2. Once NH.sub.2 is formed, then reacting the NH.sub.2 with NO.sub.x to form N.sub.2 and water. In one specific embodiment of the present invention, the method entails removing ammonia from a gas stream associated with a cement producing process. In particular, a raw feed is directed into a pyroprocessing system of a cement manufacturing facility. This raw feed is heated and in the process of producing cement, a gas stream results. Ammonia present in the gas stream is removed or substantially reduced by irradiating the gas stream and disassociating hydrogen free radicals from the ammonia to form NH.sub.2. NH.sub.2 is then reacted with NO.sub.x to form water.