Abstract: The invention relates to improvements in or relating to a desuperheater for controllable injection of cooling water in a steam or gas line (17), said desuperheater device including an insertion tube (1) extending inside the pipe (17), said tube (1) having a conical outlet nozzle (7) with a valve body (5) movably arranged in a hole (2) in the insertion tube (1) such as to form a regulating port (4). The hole (2) in the insertion tube (1) opens out into a rotation chamber (3) with the centerline (10) of the hole and the centerline (11) of the rotation chamber (3) disposed relative each other at an angle deviating from 90.degree. by an angle .alpha., and where the angle .alpha. is greater than 0.degree. but less than 30.degree..