In this work, we propose a study of the SO2 mass-transfer rate in an absorption process based on the use of an aqueous solution of ammonia (NH3), which reacts with SO2 to give ammonium sulfite according to follow overall reaction SO2 + 2NH3 + H2O ? (NH4)2SO3. An experimental and modelling study is carried out to define the thermodynamic and kinetic aspects of the ammonia-based Flue Gas Desulfurization (FGD) process. A dataset of SO2 solubility in aqueous ammonia solutions was estimated by simulations in ASPEN PLUS using an equilibrium model based on data provided in the relevant literature. The Enhancement factors (EL) for the SO2 ammonia-based absorption are determined under the explored experimental conditions: different gas and liquid flow rates, and feed molar NH3(aq)/SO2(g) ratios, varying both concentrations of ammonia in the liquid and sulfur dioxide in the gas streams.