Abstract: A mass and heat transfer device uses a substantially vertical surface to separating a first fluid space from a second fluid space with the first fluid space containing a downward flowing liquid in at least a partially flooded state and an upward flowing gas contained at least partially within the downward flowing liquid. A fluid distribution surface with one or more apertures is provided within the first fluid space with the apertures controlling the downward passage and distribution of the downward flowing liquid and the upward passage and distribution of the upward flowing gas. A heat transfer fluid is used in the second fluid space for heat transfer with fluids in the first fluid space. The fluid distribution surface can be used in a horizontal, vertical or angled position and in annular, cylindrical, and hexahedral forms.