In an apparatus for the treatment of metallic workpieces (4) with cooling gas, having a cylindrical housing (3) with an opening at the end face for introducing and removing the workpieces (4), two support plates (6, 7) extending in parallel planes vertically in the housing (3) and two air-guiding plates (14, 15) are provided, the workpiece batch (4) being held between the support plates (6, 7), and the air-guiding plates (14, 15) each forming, with the adjacent support plates (6, 7) and with the respectively adjacent inner wall of the housing, shafts (16, 17 and 26, 27, respectively) through which the cooling gas conveyed by blowers held on the housing (3) flows, controlled by reversing flaps (18, 19, 20, 21) arranged at the upper and lower ends of the air-guiding plates (14, 15).