effIcIency of unDerGrounD GAs GenerAtor In consIDerAtIonof the reverse MoDe purpose. Activation of the processes of well underground coal gasification with the consideration of the reverse mode of the underground gas generator based on the balanced state between the oxidizing and reducing zones of the fire face.Methodology. The underground gas generator efficiency was evaluated based on the analytical and laboratory studies. Analyti cal substantiation of the implementation of reverse operations in terms of the underground gas generator is based on the quantita tive parameters of coal gasification in the oxidizing and reducing zones of the underground gas generator and their advance rates. Laboratory studies were carried out on a stand unit with the modeling of the coal gasification processes.findings. Efficiency of the underground gas generator operation by reversing with blowing mixtures has been substantiated, which helps to maintain the balance between its oxidizing and reducing zones. Time periods for the reverse operations have been identified on the basis of the averaged value of concentrations of the combustible generator gases on the outlet from the modeled underground gas generator.originality. Dependences of the changes in displacements of the active underground gas generator zones in terms of the imple mented reverse of blowing mixture supply have been obtained with the consideration of mining and geological conditions of the occurrence of coal seam c 6 of Solenivska site of Donets coalfield. Parameters of the temperature field distribution around the fire face of the underground gas generator have been identified. Correction coefficient (k v ) has been determined, which helps to obtain the data on the advance rate of the oxidizing zone of the underground gas generator with the use of "MTB WUCG" software. practical value. A design of the laboratory stand unit for coal gasification has been improved, which simplifies the control of technological processes while studying gasification modes. Operating efficiency of the underground gas generator with the transi tion to the reverse mode has been substantiated on the basis of energy balance of the active zones of the reaction channel and composition of the generator gas.