Chemical absorption is the most common technology used for the process of CO2 removal from natural gas due to its ability to reduce the level of the acid gas to a very low level as well as higher mass transfer performance due to the chemical kinetic reaction. Higher solvent concentration resulted in higher capacity to remove CO2, however reduces the diffusivity as well as its ability to spread on the packing due to its high solvent viscosity. This has hindered the used of high viscosity solvent in the operation of conventional packed column. However, recent technology of using high frequency ultrasonic irradiation for absorption process has shown possibility to operate high viscosity solvent due to the absence of packing in the reactor. From this work, it is shown that high viscosity solvent does not affect the mass transfer performance under ultrasonic irradiation due to the presence of acoustic streaming, fountain and atomization that reduced the film resistance thus increases the diffusivity. This work has demonstrated that this technology has high flexibility of solvent selection for the absorption process. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/)