Abstract: Sulfur dioxide and other sulfur compounds are removed from various waste gas streams including those from incineration, refinery sulfur processing, coal burning, or metal smelting operations. The process for sulfur compound removal comprises, in an adsorption vessel, the quenching and subsequent adsorption of the gas with a suitable adsorbent such as an aqueous basic solution (e.g. sodium hydroxide). Sulfur compounds are thus adsorbed into a liquid scrubbing solution predominantly in the form of partially oxidized species (i.e. sulfites, bisulfites, thiosulfites, sulfides, and bisulfides). In a separate heterogeneous catalytic oxidation step, these partially oxidized sulfur compounds are more completely oxidized so that the chemical oxygen demand of the effluent from the oxidation reactor is substantially reduced.