Abstract There is a continuously increasing interest in the exploitation of alternative sources of energy (wind, water, geothermal energy and biomass) especially in the industrially developed countries. The most perspective exploitation of them in central-European European union countries has biomass. The main advantages of the energetic exploitation of biomass are the facts that biomass is a renewable natural resource, it is neutral fuel concerning production of air pollutant emissions, it has negligible content of sulphur and it is independent from import of primary energetic sources of power. The purpose of the thesis is to describe the exploitation of biomass as an alternative source of power by the gasification process in the fluid reactor and in combination with the addition of the concrete percent amount of charcoal for the purpose of the increase of fuel value of the generated syn gas as well as for the purpose of the efficiency of the gasifying reactor. The gasification is a thermo-chemical transformation of biomass as well as the combustion and the pyrolysis. The gasification of biomass has in comparison with its combustion these advantages: transformation of solid fuel into gas fuel, possibility of the consecutive combustion and the possibility to use different types of biomass. The theoretical part of the thesis is focused on the description of principles of the following: the gasification process, the technologies of the fluid reactors. The second part is focused on the research and the evaluation of the very progression of the gasification process by using concrete alternative fuel depending on the excess of the gasifying air, with the focus on the gasification process with the reference to the concentration of the combustive compounds of the syn gas, to the thermal progression of this process and to the heat value of the analysed gas. All the experimental measures were performed on the experimental gasification device constructed at The Department of Furnaces and Thermal Technology, Faculty of Metallurgy, The Technical University of Košice, for the purpose of the gasification of the alternative fuels.