The direct sulfation reaction is defined as the sulfation reaction between SO2 and limestone in an uncalcined state, and is typically relevant for flue gas desulfurization by direct sorbent injection during pressurized fluid-bed combustion (PFBC) and SO2 absorption on limestone in the cyclone preheater used in cement production. In the past decades, this reaction has been extensively studied due to its potential for providing an economical control of SO2 emissions during PFBC and other similar processes. In this paper, a literature review of the direct sulfation reaction is presented. Various subjects, such as the influence of the reaction conditions (gas concentrations, temperature and system pressure), limestone properties and additives to the reaction kinetics, the reaction mechanism and modeling, are discussed. (C) 2006 Elsevier Ltd. All rights reserved.