In this work, we present a comparative study of physical properties and CO2 solubility of two ionic liquids (ILs), protic trimethylammonium bis[(trifluoromethyl)sulfonyl]imide and aprotic trimethylsulfonium bis [(trifluoromethyl) sulfonyl]imide in mixture with glutaronitrile (GLN). The effect of temperature on density and viscosity of mixtures was studied and discussed in terms of intra- and intermolecular interactions. Applying Glasser's theory, standard molar entropy, S-0, and the crystal energy, U-POT of the IL/GLN mixtures were estimated, showing a positive contribution of ILs to these quantities. This positive contribution to the entropy variation by the addition of an IL is because of the fact that it destroys GLN-GLN interactions, replacing them with new cation-GLN and anion-GLN interactions. The deconstructing effect of S-111 is greater because there are no strong S-111-GLN interactions, unlike the ammonium cation which can establish H-bonds with C = N groups. The CO2 solubilities in both (IL/GLN) mixtures expressed by CO2 molar fractions, x(CO2), or the Henry constant K-H/MPa showed that the [S-111] [TFSI]/GLN solubilizes more CO2 than the [HN111] [TFSI]/GLN throughout the temperature range. The solubility of CO2 is sensitive to the cation nature and temperature. The sulfonium cation promotes CO2 solubility because it is less cluttered than the ammonium cation unlike HN111 which is the hydrogen-binding seat (NH-GLN) with GLN. Finally, the thermodynamic parameters such as the standard enthalpy Delta H-diss(0), the free enthalpy Delta(diss)G(0), and the entropy Delta S-diss(0) of CO2 dissolution were calculated. They showed that the dissolution of CO2 did not depend on the molecular organization (small variation in entropy) but that it is linked to the intermolecular interactions in the IL/GLN mixture, as shown by the difference in Delta H-max.