3 gaseous mixtures of CO2, SO2, and NO2 were simultaneously absorbed into 1, 8-diamino-p-menthane (DAM) in a stirred, semi-batch tank with a planar, gas-liquid interface within a range of 0-2.0 kmol/m3 of DAM, 0.05-0.3 atm of CO2, 0.0025-0.04 atm of SO2, and 298.15-323.15 K at a fixed NO2 of 0.001 atm to measure their total molar fluxes. Diffusivity and Henry constants of CO2, SO2, and NO2 were obtained using the reference data, measured by N2O analogy. The mass transfer coefficient of each gas, needed to obtain the absorption rate without a chemical reaction, was modified with viscosity of aqueous DAM solution. In CO2-SO2-NO2-DAM system accompanied by firstorder reaction with respect to CO2 and instantaneous reactions with respect to SO2 and NO2, the enhancement factors of CO2 and SO2 were obtained by using an approximate solution of mass balances consisting of reaction regimes of two gases, one of which reacts instantaneously, and then, the enhancement factor of NO2 by comparing the instantaneous rates of SO2 and NO2. The observed values of the molar flux approached to the calculated values very well.