Two calcium-based absorbents, hydrated lime and calcium carbonate slurries, were employed for studies on absorption of SO2 from simulated flue gases in semi-batch bubble column and foam-bed slurry reactors. The concentration of SO2 at the inlet to, and exit from, the reactor was measured using a ZRJFAY36, Fuji, Japan make infrared SO2 analyzer. Different surface-active agents were used for studies of performance of the foam-bed reactor for the desulfurization operation. With the bubble column reactor, the maximum value of the transient SO2 removal efficiency obtained was 99.4% with hydrated lime slurry, while with the use of calcium carbonate slurry this value was 97.7%. In the foam-bed reactor, the maximum removal efficiencies were found to reduce, more with lime slurry: 91% with each of Triton X-100 and Tween 80, but to 95.2% and 96%, respectively, when calcium carbonate was used as the absorbent. The products obtained from the desulfurization operation were characterized using FT-IR and TGA analyses. Calcium sulfate hemihydrate was obtained for all the combinations of absorbents without and with the surfactant additives, except in the case where Teepol was added to the hydrated lime slurry and gypsum was obtained as the FGD product.