Abstract: A process and apparatus for removing sulfur oxides and nitrogen oxides from the gaseous combustion products of sulfur-containing fossil fuel, such as high sulfur coal, comprising passing the combustion products into a reaction chamber, introducing atomic oxygen and air into the chamber, subjecting the resulting gaseous mixture to a plurality of confined, upwardly spiralling vortical movements in series, maintaining a reservoir of sulfuric acid in the reaction chamber, each vortical movement being of sufficient velocity as to atomize and elevate the sulfuric acid in the reservoir and to intermix it with the combustion products, impinging the vortical mixture against rapidly rotating surfaces whereby to discharge the mixture outwardly against the chamber walls to fall by gravity into the reservoir, and repeating the plurality of vortical movements in series in at least one additional reaction chamber, thereby producing sulfuric acid and/or nitrosyl sulfuric acid as a saleable by-product and reducing the sulfur