Power production based on oil shale combustion is accompanied by high carbon dioxide emissions and by the formation of alkaline waste ash. A set of laboratory experiments was carried out in order to investigate the interactions in the heterogeneous system: water suspension of ash-flue gases. Suspensions of ash were treated with model gases imitating the content Of CO2 and SO2 in flue gases and air. Comparative experiments were carried out using the model system: suspension of pure CaO-flue gases. The aim of the experiments was to achieve the complete carbonation of oil shale ash by CO2 from flue gases. Experiments indicated that ash can be completely carbonated if the pH value of suspensions decreases to 9-7. The total amount of bound CO2 reached up to 153.8 kg per ton of oil shale ash or 70.8 kg per ton of oil shale burnt for electricity production. The part of bound CO2 formed 35.6 and 7.3% from the carbonate and total emission Of CO2, respectively. Due to carbon dioxide binding, alkaline ash will be chemically stabilized and its hazardous environmental effect decreased.