The concentrations of carbon dioxide range from 20 to over 40% in digestor gas. The CO2 can be removed from the biogas in order to increase the calorific values. One of the practical approaches for upgrading the biogas is water scrubbing. The solubility of gases in water follows the Henry's law. In this study, a series of experiments was conducted for CO2 absorption into water under the different flow and pressure conditions. The absorption tower was filled with 2" plastic pall rings. At the pressure of 10kgf/cm2, about 95% of CO2 was removed in the synthetic biogas, which is composed of 45% of CO2 and 55% of nitrogen. The removal rate was maintained even when the gas flow rate was at 15 LPM and water flow at 3 LPM. The results could be used in estimating mass transfer coefficient for the pall rings, and then for designing CO2 absorption tower for biogas upgrading.