The paper gives an overview of stationary source NOx control technology. Fuel combustion is the major source of NOx emissions in populated areas. In the U.S., stationary combustion sources account for 53% of the NOx produced by human activity; industrial non-combustion sources produce about 2%. The rest is produced by mobile sources. Stationary source emissions can be controlled by modifying the combustion process or by post-combustion treatment. Conventional combustion modification can reduce NOx by up to 50%; advanced techniques have the potential for over 80% reduction. Post-combustion treatment can achieve up to 90% control; however, costs may be substantially higher than those for combustion modification.