As the short-time HTST treatment, the extrusion-cooking is one of the most effective treatment methods which only slightly reduce the nutritional value of components. The extrusion-cooking is suitable as a processing method of many food and feed products, e.g. crisps, pasta, breakfast cereals, instant products, flat bread, confectionery, and many others. Some additives, as enzymes, can be used to change characteristics of the final products, but they have also an impact on the processing and quality of extruded products. The aim of this study was the evaluation the effect of different fungal xylanase level and variable extrusion-cooking conditions on the processing efficiency (Q) and specific mechanical energy (SME) consumption during combined enzymatic-hydrothermal treatment. The extrusion-cooking variable conditions were applied to combined hydrothermal and enzymatic treatment with the application of xylanase enzyme. Single-screw extruder with two configurations of plasticizing unit at L/D = 16 and L/D = 20 was used in the experiment. Wheat flour type 750 was fortified with the addition of xylanase in the amount of 50 and 100 ppm and processed at the screw speeds ranged from 40 to 80 rpm with the flour initial moisture content of 25 and 27%. During the extrusion-cooking the processing efficiency was registered and the specific mechanical energy consumption was calculated. The results obtained for the extruded flours enriched with xylanase addition showed significant differences in processing efficiency and specific energy consumption, especially if various L/D were applied at the moisture initial level of 25%. Processing efficiency increased when the longer version of the extruder was applied, especially at the highest screw speed. Xylanase addition increased Q values when low screw speed was applied during processing. Lower initial moisture level of extruded wheat flour caused higher SME values if sample was processed at higher screw speed with L/D=16 version. Application of xylanase enzyme at the level of 50 and 100 ppm in extruded wheat flour increased SME in longer L/D configuration when 25% of moisture and 40 rpm were applied.