The paper provides high-temperature isothermal data on SO2 capture by calcium-based sorbents, obtained in a dispersed-phase reactor for limestones, dolomites, hydrated calcitic limes, and hydrated dolomitic limes as a function of Ca/S molar ratio, temperature, and SO2 partial pressure. The experimental results indicate that SO2 capture is approximately linearly dependent on Ca/S molar ratio and relatively insensitive to SO2 partial pressure above 2000 ppm. SO2 capture is a strong function of general sorbent class; dolomitic sorbents are better than calcitic materials on an equivalent calcium basis, and hydrated materials are more reactive than carbonates. Computer model predictions based on a grain formulation, available fundamental rate data, and measured surface areas accurately predict limestone performance; however, predicted capture for the hydrated sorbents is significantly below that measured experimentally. The measured capture results do, however, generally correlate with the BET surface areas measured when the sorbents were calcined in a muffle furnace at 980 K for 20 minutes with an inert environment.