Abstract: There is described a catalyst element (1) consisting of an integral whole having channels (2) extending therethrough. These channels (2) have, in circumferential sense of the cross section thereof, at least one concave wall portion and at least one convex wall portion, preferably provided by longitudinal projections (4) or grooves (7). As a result, a liquid phase (10) will preferentially be located in cavities (5) defined along the channel walls, and a gas phase (20) will preferentially be located centrally in the channels (2). Consequently, the catalyst element (1) according to the invention offers the possibility of being operated in countercurrent mode with only a slight loss of pressure.