AbstractThe performance of perforated and porous plates in achieving contact between gas and liquid in an absorption process is described. A mixture of carbon dioxide and air is passed upwards through a porous disk forming the base of a column containing liquid absorbent and is disseminated throughout the liquid as a mass of bubbles. 30% v/v monoethanolamine is used as absorbent in quantitative tests and the behaviour of other liquids is studied qualitatively. A distinction is made between two types of absorption taking place in the column. Absorption at the plate surface is extremely active and is essentially complete within a very small compass. Absorption throughout the remainder of the column is much less efficient per unit space and more akin to that of ordinary absorption towers. The influence of various factors (total gas flow rate, and the number, cross‐sectional area, and position of perforations) on ‘plate surface’ absorption is expressed quantitatively. The absorptive behaviour of commercial porous plates broadly follows that of perforated plates but, owing to a less standardised distribution of pores, is not so well defined. The effect on absorption efficiency of change in the flow pattern of the foaming liquor is traced.