Absorption rates of CO2 into aqueous solution of N-methyldiethanolamine (MDEA) blended with diethanolamine (DEA) were investigated by a laboratory disk column, in the temperature range from 313 to 343 K and a weight ratio of MDEA to DEA of from 50/3 to 50/10 at a total amine concentration of 3.0 M. According to the suggested homogeneous activation mechanism, kinetics of model of CO2 absorption into aqueous solution of MDEA blended with DEA was established and the absorption rate can be expressed as N-CO2 = H(CO2)rootD(CO2)(k(MDEA)C(MDEA)+k(DEA)C(DEA)) (p(CO2) -p(CO2)*). An equation of second-order reaction rate constant between CO2 with DEA, In k(DEA) = 24.515 - 5411.3/T, has been obtained, and it is in good agreement with that of literature reported on CO2 absorption into single DEA aqueous solutions.