An automatic device for heating and frothing a liquid, in particular milk, comprises a container which is provided with an opening for the introduction of the liquid and is associated with a duct for introducing into the liquid pressurised steam for heating the liquid itself and creating turbulence therein, and air, which duct has, in an internal end portion, a set of openings or nozzles distributed along said end portion and is arranged so as to send steam into the liquid according to a predetermined trajectory.