This paper was aimed at the thermal decomposition and kinetics of the byproducts from MgO flue gas desulfurization. The effects of particle size and charcoal on thermal decomposition of the byproducts were investigated by the thermogravimetric analysis method, and the non-isothermal kinetic parameters of the byproducts were evaluated with the Coats-Redfern method. The results showed that the mass loss increased with the decrement of the particle size. However, the effect of the particle size on the mass loss of each thermal decomposition stage was different. Increasing the amount of charcoal powder in the byproducts had an obvious effect on the temperature characteristics of the thermal decomposition of magnesium sulfate, resulting in a reduced thermal decomposition temperature which could facilitate the thermal decomposition process. The equations G(alpha) = 1-(1-alpha)(1/2), G(alpha) = [-ln(1-alpha)](2), and G(alpha) = 1-(1-alpha)(1/3) were the quite appropriate kinetic mechanisms describing the thermal decomposition process of MgCO3, MgSO3, and MgSO4, respectively. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.