As a result of shrinking fossil fuels biomass as a regenerative energy source gains in importance. To realize biomass projects it is essential to investigate convenient thermal procedures. On this evidence an analysis and evaluation of diverse gasification technologies with different boundary conditions and diverse biomasses is indispensable. Form and kind of the biomass as well as the type of the gasification plant cause different compositions of the product gas. The gasifiers show advantages and disadvantages concerning the biomass and the produced gas quality, depending on reactor type, kind of heat supply, gasification medium, and the pressure ratio in the reactor. As the ideal gasifier for different biomass is presently not available it will be shown which biomass is suitable for fixed bed or fluidised bed gasifiers.