The paper considers methods of NOx inhibition by affecting the process of NOx formation. The dependences for the degree of NOx concentration reduction while intensifying the flame cooling, during water spray to the furnace, and while using flue gases recirculation as well as during fuel emulsification or nonstoichiometric fuel combustion have been obtained. The obtained formulas include a set of parameters which could affect the final value of NOx concentration. The effect of a given factor could be evaluated on the basis of these dependencies. The calculated degrees of NOx inhibition display good agreement with full-scale experimental data. The authors study the effect of NOx concentration on ignition of the alternative hydrogen fuel during co-combustion in the furnace volume. The analysis of experimental data on hydrogen ignition delay in the presence of nitrogen oxides has been carried out. It is shown that depending on NOx concentration, minimum ignition delay could occur, i.e. minimum effect of additives on the quality of alternative hydrogen fuel combustion may be allowable. The results of the study could be used for design engineering of power plants with the reduced NOx environmental effect. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.