Carbon Capture and Storage (CCS) is a solid option for CO2 mitigation in the atmosphere. One option is the CO2 capture from industrial effluents followed by storage in secured sites. Capture processes are based on selective absorption/desorption cycles of gas in aqueous solutions of amines[1]. The cost of CO2 treatment with classical alkanolamines is a limitation for the use of this technology. The development of breakthrough technologies is needed to optimize the separation process. One of the considered option is the use of a new class of amine : the demixing amines. Those amines are going through a liquid-liquid separation phase when increasing the temperature[2]. This very interesting property allows to treat only a part of the absorbent solution for the regeneration of the CO2 in the absorption/desorption cycle. The use of such new system induced the perfect knowledge of the liquid-liquid equilibriums (LLE) in the binary mixtures water + amine, and the influence of the CO2 on such equilibriums. The aim of this paper is to present a method developed in the laboratory to study precisely the LLE in the binary solutions water + amines and the ternary mixtures water+amine+CO2, as a function of the pressure and the CO2 loading charge. This work is realized with the financial support of ANR and NSERC through an international collaborative project between France and Canada named DACOOTA.