The conversion of biomass to renewable biofuels by mixed alcohol synthesis (MAS) becomes more and more important because of its benefits compared with other fuels like pure methanol or ethanol. Mixed alcohol fuels have for example higher octane numbers than other biofuels. Advantageous is also the possibility to blend them with methanol or ethanol due to their ability to act as a solvent. In addition to these benefits, mixed alcohol fuels are environmentally beneficial as a result of the use of renewable resources as feedstock, like biomass. The master thesis investigates a thermo-chemical process for the conversion of biomass to a renewable biofuel mixture in pilot plant scale. The produced biofuels are primarily ethanol as well as methanol, propanol, butanol and pentanol. For this purpose a pilot plant was built at the location of the combined heat and power (CHP) plant Güssing to produce mixed alcohols. The synthesis gas was taken directly from the gasifier installed at the CHP plant. The mixed alcohol synthesis as well as the biomass gasification are described and discussed in this work. It should be noted that in this MAS pilot plant real synthesis gas from biomass is used in contrast to other work on MAS. In the course of this work, a test run with ten experiments was carried out on the MAS pilot plant. During this test run temperatures and pressures of the several plant sections were measured online via an automation and visualisation program. A parameter variation of temperatures and pressures was made too. Furthermore, the gas composition of the synthesis gas and the MAS product was analysed by means of gas chromatography.