The paper presents results of the analysis of waste from semi-dry flue gas desulphurisation installation called Integrated Novel Desulphurisation (NID). A comprehensive analysis of the physicochemical properties was conducted, including analyzes of the content of ions SO32- and SO42- (relating to 2CaSO3·H2O i CaSO4·2H2O), moisture, SiO2 and R2O3 and SEM-EDX analysis. The original method for the determination of sulphates (IV) using a potentiometric titrator was designed. Determined that the main component of both studied wastes was 2CaSO3·H2O, and its content is for NID 1 – 41,24±0,63%, for NID 2 – 45,53±0,33%. The content of CaSO4·2H2O, which was determined by gravimetric method amounted for the NID 1 – 8,92±0,12%, for the NID 2 – 8,27±0,08%. The moisture content for both tested materials was about 4%, the content of SiO2 was in the range of 8–10%, and R2O3 content was about 1%. It was also shown that the test material is not homogenous. Images from scanning electron microscope showed that in the waste occured irregularly agglomerates with a diameter between 30 and 100 microns. EDX analysis revealed that elements constituted NID wastes are oxygen, sulfur, calcium, chlorine, silicon, aluminum, copper and carbon.