There are still severe problems with high solid concentrations during the enzymatic hydrolysis of lignocellulosic biomass in stirred tank reactors. Thus, the integration of the thermal pretreatment and the enzymatic hydrolysis of the biomass in the same fixed bed reactor is investigated in this work. The influence of pumps on the enzyme activity is shown to be negligible for later applications although sharp pressure drops in valves decrease enzymatic activity. Mechanical treatment upfront to the thermal hydrolysis shows good results during the enzymatic reaction (yield > 95% after 48 h for pelletized straw). Finally the success of the enzymatic reaction in a fixed bed reactor with different solid contents (7 - 20%) is presented.