Fine particles of waste cement are produced as a byproduct in the recycling processes of aggregates from waste concrete. Along with a rapid increase in the emission rate of waste concrete by demolishing concrete buildings, especially in Japan and China, the emission rate of waste cement is quickly increasing these days. And it is projected that this increasing trend will continue at least over next several decades. However, a large portion of the waste cement particles has been disposed of without being reused. The main component of the waste cement is calcium silicate hydrate gel ((CaO)x-(SiO2)y-(H2O)z), and calcium hydroxide, Ca(OH)2. Since both components are known to have high abilities of the SO2 absorption, it is expected that the waste cement particles could be used as a sorbent for the flue gas desulphurization. In this study, desulfurization performances of waste cement particles were examined in a laboratory-scale experimental apparatus. The waste cement particles produced in a commercialized recycling process of aggregates from waste concrete were used. BET surface area and pore volume of waste cement particles were investigated. The diameter of the wasted cement particles was distributed in the range of 10 ~ 200 µm. After classified into several groups by thieving, a known amount of the waste cement particles were mounted in a sample cell of thermo-gravimetic analyzer (TG-DTA), and the weight changes of the sample particles due to the exposure to gas flow containing SO2 were measured. The SO2 concentration in the gas flow was changed in the range of 60 ppm ~ 1500 ppm balanced with nitrogen and oxygen. The oxygen concentration was changed in the range of 0 ~ 10 %. The reaction temperature was changed in the range of 650 ~ 1050 °C. The weight of the waste cement sample was found to increase with increasing SO2 exposure time, due to the desulphurization reaction. Higher desulphurization rates were observed for the waste cement particles with smaller particle size ranges. The desulphurization rate was increased with increasing the concentrations of SO2 and O2 in the gas flow. The desulfurization rate was increased with increasing temperature in the range of 650 to 950 °C. However, the rate was decreased when temperature was increased higher than 950 °C. The desulphurization rate of the waste cement, based on the weight of the absorbent, was lower than that of calcium hydroxide or calcium carbonate. However, the waste cement as a desulphurization sorbent would be advantageous in terms of the cost over calcium hydroxide or calcium carbonate. In addition, the effective use of waste cement is demanded in terms of reduction of waste streams.