The absorption of CO2 into aqueous mixtures of 2-amino-2-methyl-1-propanol (AMP) and piperazine was investigated. A wetted-sphere absorption apparatus was used to measure the absorption rate. The absorption rates of CO2 into aqueous solutions of AMP in the range of 0.55-3.35 kmol/m(3) were measured. The experimental temperatures were 303 and 313 K. The zwitterion deprotonation mechanism was used to interpret the kinetic data of aqueous solutions of AMP. The absorption rates of aqueous mixtures of AMP and piperazine were measured. Piperazine concentrations of 0.058, 0.115, and 0.233 kmol/m3 were added for each AMP solution. The apparent reaction rate constants increased with the addition of piperazine. The effect of piperazine on the reaction rate of CO2 with aqueous solutions of AMP consists of the contribution for the zwitterion deprotonation and the direct reaction of piperazine with CO2. The zwitterion deprotonation constants of all bases presented in liquid and the direct reaction rate constant of piperazine were obtained.