Abstract: A process for regenerating a moisture charged drying cartridge and apparatus for carrying out the process. Drying cartridges are used to prepare drying air for drying synthetic plastics in the form of granulates or powders. Used drying air, which has become charged with moisture, is passed through a drying cartridge which takes up the moisture from the drying air. The dried drying air can then be passed again through the material to be dried. In regenerating a spent, moisute laden drying cartridge, external air is collected, heated and exhausted after passage through the cartridge, which subsequently must be cooled. In order to achieve the lowest possible dew point after regeneration of a cartridge to be dried with a minimum consumption of energy, the regeneration air is passed in a closed regeneration circuit (11) through the cartridge (9').