Measurements for the rates of absorption of carbon dioxide from carbon dioxide-air mixtures with a water and an aqueous sodium hydroxide solution drop falling freely were made for Fourier number Fo = 1.53 x 10(-5) - 9.83 x 10(-5), initial concentration of aqueous sodium hydroxide solution C-BO = 0.05 - 0.4 mol/l and feed gas concentration of carbon dioxide y = 0.05 - 1.0. Observed dimensionless rates of absorption were compared with the theoretical values by the present model and gave a good agreement with theory. The effect of drop diameter on the enhancement factor, which is a measure of the effect of chemical reaction on the rates of absorption of carbon dioxide with a freely falling alkaline solution drop, were also discussed by using numerical simulation.