The monograph deals with the problems of increasing the effi ciency of fuel combustion and reducing emissions of harmful substances in boilers with a capacity of up to 3.5 MW. Approaches for the formation of stoichiometric air-fuel mixtures in boilers are developed. Th e method for indirect determination of the concentration of air components was developed, which allows to increase the metrological characteristics of gas-analyzing devices. Methods, algorithms and programs to automate the combustion control process, while ensuring the reliability of the data, are created. A system for monitoring the fuel combustion process was developed, and it was implemented on the basis of the NIISTU-5 boiler unit. For researchers, engineers, as well as lecturers and postgraduates of higher educational institutions and scientifi c institutions, working in the fi eld of engineering and optimization in the energy.