This paper presents a study on the hydrodynamics and mass transfer performance of absorption of CO2 into deionized water and DEA solutions in a microreactor under elevated pressures up to 4.0 MPa. It is demonstrated that increasing gas density (system pressure) leads to increased pressure drop. Considering such effect, a modified Lockhart-Martinelli model is developed, showing good prediction over the two-phase pressure drop. For the mass transfer performance, parametric studies by varying system pressure, temperature of feeding fluids, molar ratio of DEA/CO2 and CO2-loaded DEA solutions are presented. Two empirical correlations based on the power consumption are developed for the prediction of mass transfer coefficients in physical and chemical absorptions, respectively. The results suggest significant intensification is achieved in the microreactor. Besides, dramatic increase of CO2 loading in the rich absorbents is also obtained, which is very attractive for solvent regeneration. The findings in this paper can serve as guidance in the design of processes with high-pressure operations, such as natural gas purification or biogas recovery.(C) 2017 Elsevier B.V. All rights reserved.