A development program on pressurized fluidized-bed combustion is being carried out in a bench-scale pilot plant capable of operating at 10-atm pressure. The concept involves burning fuels such as coal in a fluidized bed of particulate lime additive that reacts with the sulfur compounds formed during combustion to reduce air pollution. Nitrogen oxide emissions are also reduced at the combustion temperatures used, which are lower than those used in a conventional coal combustor. The CaSO/sub 4/ produced in the combustor is regenerated to CaO that is recycled to the combustor for removal of sulfur compounds. Information is presented on bench-scale regeneration experiments, TGA experiments on sulfation and regeneration rates of synthetic SO/sub 2/-sorbents containing metal oxides, bench-scale combustion experiments, regeneration by the CaSO/sub 4/-CaS reactions, coal combustion reactions, status of equipment fabrication, and mathematical modeling of the gas-solid combustion reactions. Current objectives are (1) to select and optimize a regeneration process, (2) to test the behavior of different limestones, dolomites, and synthetic additives during combustion and regeneration, and (3) to assess the behavior of biologically toxic trace elements and corrosive elements.