The effect of physicochemical parameters on the kinetics of the desorption of SO2 with an instantaneous reversible chemical reaction in the liquid phase was studied. We have employed a mathematical model of the thermal desorption of SO2 from sodium sulphite solutions, which occurs in a packed column coupled with a boiler heated indirectly. It is shown that the equilibrium parameter which combines sulphur dioxide partial pressure with the composition of sodium sulphite solution plays a crucial role in the design and optimisation of the process.