The research aim is a theoretical substantiation of the increase in the efficiency of extrudate dehydration due to the supply of air into the vacuum chamber of a modernized extruder with a thermal vacuum working process. On the basis of modern study of the implementation of the thermodynamic process in the interaction of three different air flows in a limited volume of the vacuum chamber of the extruder, one possible way of increasing the efficiency of the finished product dehydration was theoretically justified. In the previously proposed constructive-technological scheme of the extruder, the insufficiently intensive dehydration of the finished product leaving the die of the ma-chine is associated with a relatively low air flow rate at the surface of the cooling extruder. These speed limits the transfer rate of the liquid removed from the extruder by means of wet steam, which is withdrawn from the vacuum chamber of the extruder into a vacuum balloon and condenses. In a modernized extruder, the effect of thermal vac-uum effect is proposed to be enhanced by means of a metered supply of air into the working volume of the extrud-er’s vacuum chamber. The conducted research allowed obtaining analytical expressions with the help of which it is possible to determine the volumetric flow rate of air injected into the vacuum chamber of the machine and to deter-mine its effect on the main structural and technological parameters of the system that ensures the thermal vacuum effect of the extrusion process. The relationship between the coefficient taking into account the influence of the thermal vacuum effect in an autogenous extruder on other significant technical and technological parameters of the machine is shown. The results obtained can be useful and considered in the course of subsequent theoretical stud-ies of extruders with a vacuum chamber and will allow on their basis increasing the efficiency of the machines per-forming the thermal vacuum extrusion of raw materials of plant origin.