Device for heating milk or milk froth with steam in a steam/liquid mixer which is equipped with a tubular mixing chamber, at least one steam supply pipe and a milk/milk froth supply nozzle aligned in the longitudinal direction of the mixing chamber. The steam supply pipe operatively discharges steam into a steam supply chamber upstream of the mixing chamber and which is connected to the mixing chamber by steam inlet holes running around the milk/milk froth supply nozzle in the longitudinal direction of the mixing chamber. The steam supply holes are preferably aligned axially parallel to the center axis of the mixing chamber. This arrangement of the steam inlet holes brings about even and thorough mixing of the steam with the cold milk or the milk froth in the mixing chamber, and so optimal heating of the milk or the milk froth.