The article discusses a mathematical model of the electrothermal process of heating the formation with a microwave electromagnetic wave, which is caused by electrical devices capable of operating under high pressure. The issues of using microwave dielectric heating to reduce the viscosity of oil-bearing deposits, which will increase the efficiency of their production, are considered. The article presents an in-depth analysis of various existing and promising methods of ensuring the production of high-viscosity oil and shows the advantages of the thermal method, and on the basis of calculations using mathematical and computer models-the prospects for using microwave radiation. Models of the electromagnetic field are shown that provide uniform heating of the sediment to a sufficient depth. The results of the work create and substantiate the basis for the development of a new technology for thermal increase in the efficiency of oil production, primarily in combined oil fields and northern regions, which are characterized by high oil viscosity.