SO2 removal efficiency of a pilot-scale spray dryer, which is located after a central heating boiler of 3 MW heating capacity, was investigated. The boiler burns No.5 fuel-oil. Removal efficiencies were studied for various trona-based sorbent solutions depending on the ratios of Na/S, which correlate to SO2 removal capacity in flue gas and sorbent solution. Up to 98% of removal efficiencies were obtained for certain sorbent concentrations and Na/S ratios. Removal efficiencies were also well-correlated with Na/S ratios in mathematical models based on the experimental data. The trona used in this study is mined from one of the world's largest trona mines in Ankara/Turkey. Study results indicate that this mine can economically and effectively be used in flue gas desulphurization processes.