We have tested the microwave device of continuous operation for the thermal treatment of plant materials, which was developed and designed to implement microwave technologies in the industry. The purpose of the tests was to assess the effectiveness of the microwave device by the indicators of quality of the obtained material and energy consumption determined by the efficiency of the conversion of microwave energy into the internal energy of the material. The effects of microwave treatment of a straw substrate for tree-destroying fungi were studied. The treatment quality was determined by the yield of Oyster (Pleurotus) mushrooms, grown on the obtained substrate. Microwave treatment was carried out in various modes, which differed in the value of specific power. When analyzing the effectiveness of microwave treatment, the results were compared with the data obtained during the application of the traditional technology of straw sterilization. It was shown that the harvest of Oyster mushrooms increased by 11 %. It was found that under the optimal mode, specific power was q v =8.68·10 5 W/m 3 , final temperature was t=96 °С, duration of treatment was 180 s. Based on the thermal calculations, the values of the microwave chamber efficiency η c were calculated; under the optimal mode, η c =62 %. The influence of the microwave treatment on the sowing characteristics of seed wheat grain was studied. The effectiveness of the microwave treatment was determined by the values of laboratory germination and seed germination energy. Under the optimal mode, the output power of magnetrons was ΣP out =0.6 kW, the grain consumption was G=2.1·10 -2 kg/s. The study of the microwave device operation showed that for this design, in order to ensure stable and uniform movement of the material along the product pipeline, it is necessary to maintain the movement speed that is not higher than 0.5 m/min. It is recommended to apply the tested microwave device of continuous operation on specialized farms