Coal, the world's most abundant, most accessible and most versatile source of fossil energy was brought to the forefront of the global energy scene by the industrial revolution of the 19th century. Like any fossil fuel, coal is associated with naturally occurring radioactive materials. This is due to their U, Th, and K content. This certainly has radiological implications not only for the miners but also for the immediate environment of the mines and the users. In this study, the radioactive elements in Manisa-Soma and Istanbul-Agacli coals and their ashes were studied. In the experimental section, the coal and thermal power plant ashes which were taken from Manisa-Soma were used. Sieve, moisture, ash, calorific value, volatile amount, total carbon, total sulphur, major element and radioactive element analysis of the samples were carried out. The float and sink analyse and flotation tests were carried out on the samples which were taken from Manisa-Soma and Istanbul-Agacli. Thus, radioactive elements changes and moving mechanisms were investigated with coal preparation and burning methods. Furthermore, the pre-investigation of the assessment of the thermal power plant ashes was carried out with the experiments on the ash samples, which were taken from the Soma thermal power plant.