A vapor horn device for use in an elongated, generally upright mass transfer and/or heat exchange column having an internal region comprises an elongated, generally arcuate wall arranged to be located within the internal region and disposed to extend around a longitudinal axis of the column. The arcuate wall includes an inlet area positioned for being contacted by a vapor or mixed phase stream entering the column and causing the stream to flow along an outer surface of the arcuate wall and generally around the axis. The device also includes a primary elongated vane extending outwardly from the outer surface of the arcuate wall. This primary vane has an inner end located adjacent the outer surface of the inner wall and an outer end disposed in spaced relationship relative to the outer surface of the wall. The vane is disposed at a tangential angle relative to the direction of flow of the stream such that the inner end of the vane is further downstream than the outer end thereof whereby any portion of the stream impinging on the primary vane is redirected toward the outer surface of the arcuate wall. The device also desirably includes one or more vanes that extend radially outwardly from the inner wall.