A method to control the combustion of a compression ignition internal combustion engine with reactivity control through the injection temperature; the internal combustion engine is provided with at least one piston, which slides, with a reciprocating motion, on the inside of a cylinder, so as to carry out a succession of combustion cycles, each comprising at least an intake stroke and a compression stroke; the control method comprises the steps of: establishing, for each combustion cycle, a quantity of fuel to be injected into the cylinder; and injecting a first fraction of the quantity of fuel at least partially during the intake and/or compression stroke; injecting a second fraction of the quantity of fuel, which is equal to the remaining fraction of the quantity of fuel, into the cylinder at the end of the compression stroke; and heating the second fraction of the quantity of fuel to an injection temperature of over 100° before injecting the second fraction of the quantity of fuel; the control method is characterised in that: the first fraction is injected by means of a first fuel injector (9; 11) that receives the fuel from a first feed system without active heating devices so that the fraction of the quantity of fuel has a temperature below the injection temperature; and the second fraction of the quantity of fuel is injected by means of a second fuel injector that is different and independent from the first fuel injector (9; 11), injected directly into the cylinder, and receives the fuel from a second feed system that is separate and independent from the first feed system and wherein the second feed system or the second fuel injector is provided with at least one active heating device (12; 13) that is operated to give the fuel the injection temperature. establishing, for each combustion cycle, a quantity of fuel to be injected into the cylinder; and injecting a first fraction of the quantity of fuel at least partially during the intake and/or compression stroke; injecting a second fraction of the quantity of fuel, which is equal to the remaining fraction of the quantity of fuel, into the cylinder at the end of the compression stroke; and heating the second fraction of the quantity of fuel to an injection temperature of over 100° before injecting the second fraction of the quantity of fuel; the control method is characterised in that: the first fraction is injected by means of a first fuel injector (9; 11) that receives the fuel from a first feed system without active heating devices so that the fraction of the quantity of fuel has a temperature below the injection temperature; and the second fraction of the quantity of fuel is injected by means of a second fuel injector that is different and independent from the first fuel injector (9; 11), injected directly into the cylinder, and receives the fuel from a second feed system that is separate and independent from the first feed system and wherein the second feed system or the second fuel injector is provided with at least one active heating device (12; 13) that is operated to give the fuel the injection temperature. the first fraction is injected by means of a first fuel injector (9; 11) that receives the fuel from a first feed system without active heating devices so that the fraction of the quantity of fuel has a temperature below the injection temperature; and the second fraction of the quantity of fuel is injected by means of a second fuel injector that is different and independent from the first fuel injector (9; 11), injected directly into the cylinder, and receives the fuel from a second feed system that is separate and independent from the first feed system and wherein the second feed system or the second fuel injector is provided with at least one active heating device (12; 13) that is operated to give the fuel the injection temperature.