Abstract: A reactor having a moving layer for the removal of undesirable components for gases has an upright moving-adsorber chamber flanked by jalousie arrays of shutters laterally separating that chamber from a gas inlet chamber and a gas outlet chamber communicating through the jalousies with the adsorbent chamber. The gas inlet and gas outlet chambers, which extend over substantial portions of the height of the adsorbent chamber, are provided with the gas inlet and outlet respectively and are so oriented that the flow of gas through the adsorbent chamber is diagonal across the downward flow of the adsorbent supplied at the top of the adsorbent chamber and removed at the bottom thereof.