The aim of this study was to find out the fine-particle emissions (PM2.5) of different energy production processes in Finland. The main purpose was to compare the calculated emission factors between different energy production concepts. The purpose was also to define what is known about fine-particle emissions and what should still be studied/measured. Only those energy production processes that produce a significant amount of direct emissions of solid particles have been treated here, i.e. pulverized combustion and oil burners from burner combustion, fluidized bed combustion processes, grate boilers, recovery boilers and diesel power plants. Secondary particles from gaseous pollutants have not been considered within this study. In pulverized coal combustion the particle emission is composed mainly of particles smaller than 5 μm in aerodynamic diameter. Roughly half of the total mass of particle emission is composed of fine particles (PM2.5). Depending on boiler size category and particle separation devices, the specific emission factor for fine particles is 1–30 mg MJ−1. For pulverized combustion of peat, ca. 20–25% of the total mass of particle emission is fine particles, and then the specific emission factor is between 5 and 8 mg MJ−1. For recovery boilers, the fine particle portion of the total particle emission is 50–60% (by mass) and the specific emission factor for fine particles varies considerably according to the boiler size category, being between 12 and 77 mg MJ−1. For oil burners, grate boilers and fluidized bed combustion processes, the fine-particle portion of the total particle emission could not be determined, because there were no applicable measurement results at hand. For these combustion techniques, more public measurements are needed in order to clarify the amount and composition of fine particles with different fuel varieties. Additionally, the chemical composition of fine particles is a very important feature when human health effects caused by particulate matter are considered.