The paper contains the investigations of physical and chemical parameters of calcareous wastes as residuals in the soda production process. The possibility of using these wastes as a sorbent for dry and wet desulfurization of combustion gases from power stations is the main aim of presented data. The reactivity properties of that sorbent for dry method of desulfurization were obtained by AP test, while for wet method by ABB Flaki. On the basis of the obtained results high level of suitability of calcareous waste for wet dcsulfurization method was established (reactivity SRm* = 0.85), for dry desulfurization method suitability of the sorbent is limited by its high consumption up to 5 kg/kgSO2.