In this work we have studied the kinetic and mass-transfer behavior of spray-tower-loop absorbers and reactors. For this purpose, we have investigated mass-transfer rates in the physical absorption of CO2 in water and the effect on mass transfer of respectively a moderately fast reaction, such as the ethoxylation of nonylphenol or fatty alcohol, and an extremely fast reaction, such as the one between CO2 and an aqueous NaOH solution. Spray nozzles used have been geometrically and fluid-dynamically characterized. Experimental results have been interpreted by considering the drops to be internally stagnant or well-mixed. We have shown that an internally well-mixed drops model is more reliable. Moderately fast reactions, such as ethoxylation, (Hatta number of about 1) do not affect mass transfer, while extremely fast reactions require the introduction of an enhancement factor. We have proposed a semiempirical correlation for calculating this factor. Our work could be useful for modeling and simulating spray-tower-loop absorbers and reactors.