Two bituminous coals used in coal-fired power plants were mixed with either Ca- or Ma-based chemical additives. Coals and the mixtures were burnt in a laboratory-scale drop tube furnace, respectively. The impact of the additives on the trans formations of coal minerals, as well as on the emissions of particulate matter with an aerodynamic diameter smaller than 2.5 mu M (PM2.5), was investigated. The generated ash particles were collected using a cyclone combined with a low-pressure impactor. The physical and chemical properties of these ash particles were analyzed. The results indicate that the addition of chemical additives call affect the mineral transformation process, and thus, control the emissions of PM2.5 and PM1 during combustion. In particular, additives have a considerable impact on the particle size distribution and chemical composition of PM. wherein it improves the degree of coalescence of submicron and fine mineral particles, which reduces PM2.5 emissions. The effects of additive oil the reduction of PM2.5 emission, depend on the type of coals being used.