Today, most scientists are confident that carbon dioxide mitigation by carbon capture and storage is the most feasible option to significantly reduce the level of carbon dioxide emissions and with that reduce the impact of the greenhouse effect. The simultaneously multi component absorption of CO2, SO2 and NOx from flue gas using potassium carbonate (K2CO3) solution is believed to be both a more cost effective and attractive technology. Based on such a capture process, the main aim of this work was to investigate the effect of SO2 on the vapour-liquid equilibrium (VLE) curve and absorption efficiency of carbon dioxide using a 30w% unpromoted potassium carbonate solution. As a consequence of the absorption of SO2 into the potassium carbonate solution, it would be expected that the VLE curve of the CO2-K2CO3 system would change. This change in the VLE curve implies an inherent effect on the absorption performance and efficiency of the CO2 capture unit operation. In this thesis, a direct relationship between the absorbed SO2 and the change in the CO2 equilibrium partial pressure for the carbonate system was shown both qualitatively and quantitatively. Furthermore, identification of the reaction and the species formed during the absorption of SO2 by the carbonate solution was another aspect investigated in this thesis. This shows possible methods how the concentration of absorbed SO2 can be regulated.