Abstract: The present disclosure relates to the modifier of combustion of solid, liquid and gaseous fuels, in particular wood, natural gas, coal, mazout and other hydrocarbons, in power boilers, in closed or open chambers, wherein it contains from 10 to 30 wt. % of water, from 20 to 80 wt. % of at least one aliphatic alcohol, from 5 to 15 wt. % of carbamide or its derivatives, and from 5 to 15 wt. % of monoacetylferrocene. Object of the disclosure is also a method of modifying process of combustion of the above-mentioned fuels and a use of the modifier of fuel combustion.