The aim of this thesis was the summary of the basic scientific information about uranium. Attention is paid to the use of uranium in nuclear plants as a source of clean energy as well as an alternative substitution for fossil fuels. The six chapters discuss general characteristics, physical-chemical properties of uranium and it’s the most common compounds. An overview of uranium mining in the Slovakia and Czech Republic is presented. Overview of uranium mining in Slovakia and Czechia is mentioned. The use of uranium fuel in nuclear reactors is described. The effects of radioactive radiation on humans and the environment are also included. The risk of groundwater contamination and the need for safe disposal of radioactive waste is pointing out. Finally, the methods of separation and determination of uranium and its salts are presented.