Espresso coffee or similar drinks in manual or automatic machines is prepared by causing a forced flow of boiling water to pass through a percolation chamber containing coffee powder, in which an adjustable back pressure is created in the percolation chamber to increase the time of contact between the powder and the water. The machine includes a percolation chamber traversed by hot water and intended to contain coffee powder, a drink exit conduit, in which the conduit is in the form of a nozzle having an outlet throttled by adjustable mechanism, and a downstream emulsifying chamber having an air inlet bore.