The chemistry of current or potential so2 removal processes can be placed into four categories: (1) reduction, (2) liquefaction, (3) direct dissolution, and (4) oxidation. Methods that involve reducing so2 to elemental sulfur appear promising since this product can be easily handled, shipped, and stockpiled. Unfortunately, so2 cannot always be reduced directly when other oxidizing agents are present. Thermodynamic data indicate that some oxidizing reagents will also consume reductant at the reduction temperature. A two- stage process can be applied to waste gases that contain excessive quantities of oxygen, nitrogen oxides, and water vapor. The best sorbent for the first stage appears to be a nonalkali or nonalkaline earth medium since this medium more readily releases the so2 for reduction in the second stage.