Sulfur emission in coal power generation is a matter of great environmental concern. Limestone sorbents are widely used for reducing such emissions. This work applies thermogravimetry to determine apparent activation energy and frequency factor on the sorption of SO2 by limestone. The kinetic parameters were determined from Arrhenius plots generated from TG/DTG measurements. The experiments were carried out under isothermal conditions between 600 and 900 degrees C. A natural dolomite with a mean size of 650 mu m was used. The Arrhenius plot shows that there is a clear change on reaction mechanism in the range of temperatures between 800 and 875 degrees C. Supposedly, beyond 850 degrees C sintering comes to increasingly restrain reaction. For temperatures up to 850 degrees C the frequency factor and the apparent activation energy resulted, respectively, 1.410 s(-1) and 8.8 kJ mol(-1). (C) 2006 Elsevier B.V. All rights reserved.