A dynamic model representing an industrial flue gas desulfurization (FGD) unit has been developed. The purpose of this model is to anticipate new SO2 emission legislation and to study some industrial issues such as the influence of a NH3 slip (from the selective catalytic reduction (SCR) unit) or fly ashes (from the electrostatic precipitator). Interaction between gas, liquid, and solid phases have been taken into account as well as a detailed liquid chemistry with the main acid base equilibria and nonideal thermodynamic behavior. All major rate-controlling steps are modeled: limestone dissolution, sulfites oxidation, and precipitation of gypsum. The absorber hydrodynamic is modeled using an Euler Euler approach to represent countercurrent flow between flue gas and droplets; the oxidation reactor is modeled as a bubble reactor. Fly ash collection and solid handling were also implemented in order to predict the gypsum quality. The model results were successfully compared with industrial data acquired in the Cordemais (France) coal-fired power plant. The average deviation between model results and industrial data is 5%. Most of the differences between model and experiment are probably due to the lack of a precise and actualized liquid composition to initialize the model. The transient response of the model represents correctly the behavior encounter in the Cordemais power plant. Some detailed transient response experiments are needed in order to definitely validate the transient response of the model. The main hypotheses and parameters of the model were discussed and tested in order to quantify their respective influence. It appears that the aerodynamic hypothesis in the gas inlet zone and the droplet size estimation were affecting very significantly the model results. None of the rate-based submodel can be neglected: liquid and gas transfer, absorption enhancement factor, sulfite oxidation, and limestone dissolution. The expression of SO2 absorption enhancement factor is crucial for the good representation of SO2 absorption; our simplified enhancement factor gives good results in terms of being representative of the holding tank pH.