Abstract: Disclosed is a method and device for heat-treating plaster which is calcined to form hemihydrate plaster or anhydrite. Calcining to form hemihydrate plaster is carried out in at least one fluid bed region in which the water vapor partial pressure and material temperature are adjusted. The at least one fluid bed region can be followed by a further fluid bed region in which the anhydrite is formed and the water vapor partial pressure and material temperature are also adjusted. In addition, a fluid bed region can be provided for cooling purposes before the product-discharge point.