The report gives results of the first independent evaluation of a full-scale utility spray-dryer/baghouse dry flue gas desulfurization (FGD) system. The system treats flue gas from a nominal 100 MW of coal-fired power generation. The test program, conducted during July-October 1983, used two different coals as boiler fuels: one, a subbituminous coal and coke mixture with a nominal 1.2 percent sulfur content; and the other, a 3.4 percent sulfur Illinois bituminous coal. SO2 removal, particulate emissions, sulfuric acid removal, and extensive process data were recorded. Low sulfur coal tests indicated that 75 percent SO2 removal was achievable in the short term at reagent ratios of 0.6 to 0.7, and 90 percent SO2 removal was achievable at a reagent ratio of about 0.8. An average removal of nearly 90 percent was achieved in short-term tests with high sulfur coal at reagent ratios of 1.3 to 1.4. Calcium chloride addition to the atomizer feed slurry was found to reduce the lime addition requirements for high sulfur tests by about 25 percent.