Abstract: Activated carbon from carbonizable, e.g., organic materials is produced in either two physically separated drums which include means for transferring the superheated steam from one drum to the other or in a single drum provided with a longitudinal, axial separation wall that separates the drum into two drum halves or cavities. The separation wall can be opened, e.g., with hinged gates defining the wall, to transfer the materials from one cavity to the other. Suitable piping and valving is disclosed to effect the quenching of the non or incompletely activated carbon in one cavity and to activate the carbon in the other cavity with the superheated steam generated during the quenching of the carbon in the first cavity.