Abstract: A system for desulfurization of sulfur-containing coal comprises apparatus for comminuting sulfur-containing coal, a gas/solid reactor having an inlet and an outlet, a connection or conduit for supplying the comminuted sulfur-containing coal to the reactor inlet, and an oxidant gas generator constructed in accordance with U.S. Pat. No. 4,248,681 connected to supply an oxidant gas to the reactor. The oxidant gas produced from concentrated salt solutions contains substantial amounts of chlorine dioxide, while the oxidant gas produced from dilute salt solutions contains other oxygen-containing gases. The oxidant gas is introduced at pressures which may range from sub-atmospheric to super-atomospheric and the comminuted coal is mixed or agitated to insure efficient gas/solid contact. The oxidant gas oxidizes the sulfur contaminants of the coal to gaseous sulfur oxides which are removed from the reactor. The desulfurized comminuted coal may be slurried for pipeline transmission.