A sulfur dioxide-rich off gas stream obtained, as for example, by regeneration of a flue gas desulfurization sorbent, is treated with a hydrocarbon oil in the liquid phase at a temperature of about 250 F. to about 800*F. in order to reduce the sulfur dioxide. The hydrocarbon oil is preferably an inexpensive refinery stream, e.g., gas oil, catalytic cycle stock, or residuum. Hydrogen sulfide formed in the reduction can be reacted with a further quantity of sulfur dioxide to form elemental sulfur. At least a portion of the hydrocarbon oil after reaction with sulfur dioxide may be burned in a furnace in which flue gas containing sulfur dioxide is formed.