A heating device for an exhaust system of an internal combustion engine; the heating device comprises: a tubular body, where a combustion chamber is obtained on the inside; a fuel injector, which is mounted through a base wall of the tubular body so as to inject fuel into the combustion chamber; at least one inlet opening which can be connected to a fan so as to receive an air flow which is directed to the combustion chamber and gets mixed with the fuel; a feeding channel, which receives air from the inlet opening, surrounds an end portion of the fuel injector and ends with a nozzle, which is arranged around an injection point of the fuel injector; a spark plug, which is mounted through a side wall of the tubular body so as to trigger the combustion of a mixture of air and fuel and has electrodes (31, 32); and a static mixer, which is shaped like an annulus, is arranged along the feeding channel and around the fuel injector and is configured to generate, in the air flowing towards the nozzle, a swirling motion, which has a given direction of rotation around a longitudinal axis of the tubular body the feeding channel is delimited, on the outside, by an outer tubular body having an inner surface of the feeding channel and is delimited, on the inside, by an inner tubular body, which surrounds the fuel injector and contains, on the inside, the fuel injector; the heating device is characterized in that: the fuel injector is configured to spray at least part of the fuel against the outer tubular body; the outer tubular body has a through opening, through which a limited part of a fuel spray emitted by the fuel injector, instead of hitting the outer tubular body, flows through the outer tubular body in order to reach the electrodes (31, 32) of the spark plug; and the through opening is circumferentially shifted, in a direction contrary to the air rotation direction imparted by the static mixer, relative to an ideal line connecting an injection point of the injector to the electrodes (31, 32) of the spark plug. a tubular body, where a combustion chamber is obtained on the inside; a fuel injector, which is mounted through a base wall of the tubular body so as to inject fuel into the combustion chamber; at least one inlet opening which can be connected to a fan so as to receive an air flow which is directed to the combustion chamber and gets mixed with the fuel; a feeding channel, which receives air from the inlet opening, surrounds an end portion of the fuel injector and ends with a nozzle, which is arranged around an injection point of the fuel injector; a spark plug, which is mounted through a side wall of the tubular body so as to trigger the combustion of a mixture of air and fuel and has electrodes (31, 32); and a static mixer, which is shaped like an annulus, is arranged along the feeding channel and around the fuel injector and is configured to generate, in the air flowing towards the nozzle, a swirling motion, which has a given direction of rotation around a longitudinal axis of the tubular body the feeding channel is delimited, on the outside, by an outer tubular body having an inner surface of the feeding channel and is delimited, on the inside, by an inner tubular body, which surrounds the fuel injector and contains, on the inside, the fuel injector; the heating device is characterized in that: the fuel injector is configured to spray at least part of the fuel against the outer tubular body; the outer tubular body has a through opening, through which a limited part of a fuel spray emitted by the fuel injector, instead of hitting the outer tubular body, flows through the outer tubular body in order to reach the electrodes (31, 32) of the spark plug; and the through opening is circumferentially shifted, in a direction contrary to the air rotation direction imparted by the static mixer, relative to an ideal line connecting an injection point of the injector to the electrodes (31, 32) of the spark plug. the fuel injector is configured to spray at least part of the fuel against the outer tubular body; the outer tubular body has a through opening, through which a limited part of a fuel spray emitted by the fuel injector, instead of hitting the outer tubular body, flows through the outer tubular body in order to reach the electrodes (31, 32) of the spark plug; and the through opening is circumferentially shifted, in a direction contrary to the air rotation direction imparted by the static mixer, relative to an ideal line connecting an injection point of the injector to the electrodes (31, 32) of the spark plug.