To diversify energy sources and to address the impacts of global warming, the transformation of biomass, a renewable energy source, into fuels and chemicals is becoming increasingly necessary. The gasification technology is an efficient way of converting biomass via syngas into sustainable fuels. By-products, especially tar, are formed during the gasification process and need to be removed before further downstream processing. Mo/V/W-mixed oxides were found to be applicable for the catalytic tar oxidation in CO/H-2 atmosphere by adding a stoichiometric amount of oxygen. In temperature-programmed experiments the reactivity of different tar model compounds during the selective oxidation on Mo/V/W-mixed oxides as well as the catalytic performances of V2O5, WO3, and MoO3 during the tar oxidation were investigated.