Amines act as homogeneous catalysts for the carbon dioxide hydrolysis reaction, so that they are very effective rate promoters for carbon dioxide absorption in carbonate solutions. Experimental data show that the rate-promotion effect is a very conspicuous one, to the point where the catalysed reaction can be regarded as essentially instantaneous in comparison with diffusion phenomena. Possible mechanisms of this effect are discussed.The rate-enhancement effect is in addition to the effect that amines have on the capacity of carbonate solutions. The relationship between the rate and capacity effects is discussed.