Combustion process especially applicable to cement works, in which process it is desired to use fuels which are difficult to ignite. To do so, a flame comprising a primary zone and a secondary zone is created. The hot primary zone is created using an oxy-fuel flame, which makes it possible to preheat the fuel which is difficult to ignite so as to raise it to the suitable temperature in the secondary zone where it burns, with air, in order to create the main flame. Applications: cement, metallurgy, glass, etc.