A modified experimental technique for measuring the physical solubility of CO2 in monoethanolamine (MEA) aqueous solutions using the "N2O analogy" method is proposed in this work. The modified technique employs a scaled spiral glass tube with a small drop of mercury as a eudiometer as an alternative to a three-branch U-tube setup to keep the system pressure constant and measure the volume of a drop of absorbed gas at constant temperature. The results were in good agreement with literature values, suggesting that the technique is feasible and reliable. Compared with the three-branch U-tube setup, the new technique is easy to operate and more sensitive and accurate. The physical solubility of CO2 in aqueous MEA solutions over the full range of concentrations was measured using this modified technique over the temperature range from 298.15 to 323.15 K under a constant ambient pressure. Wang et al.'s model (Chem. Eng. J. 1992, 48, 31-40) was used to correlate the data, and the results showed that the model is good for predicting the behavior of the (monoethanolamine + water) system.