Abstract: Expandable plastic granulate can be manufactured continuously with a plastic melt being impregnated using a fluid expanding agent and the impregnated melt being granulated. The plant which includes at least one pressure producing feed apparatus for the melt, a metering apparatus for the expanding agent, contacting and homogenising apparatus for the impregnation of the melt, at least one cooler for the impregnated melt, an underwater granulator and a plant control. An elevated pressure is exerted by the liquid used during granulation to suppress the expanding action of the expanding agent in the not yet solidified granulate. A regulation of the temperature and pressure of the impregnated melt is effected at the inlet of the granulator to influence a heat take-up from the impregnated melt by the cooler or coolers.