The objective of this study was to capture toxic gases like CO2 and SO2 using imidazolium-based ionic liquids, 1-butyl 3-methyl-imidazoliumbis(trifluoromethylsulfonyl) imide and 1-ethyl 3-methyl-imidazolium acetate. In this work, DFT method of hybrid correlation functional with B3LYP/6-31++G (d, p) basis set was used to analyze the mechanism of interaction between toxic gases and ionic liquids based on cations of ionic liquids coupled with an ions of ionic liquids respectively. It has been found that [Bmim][Tf2N]-SO2 has greater binding energy than [Bmim][Tf2N]-CO2. Therefore, the ionic liquid [Bmim][Tf2N] seems to be the most suitable option for SO2 gas capture. Similarly, The ionic liquid [Emim][Ac] has high efficiency to capture the toxic gas SO2 relative to CO2. The types of absorption observed in [Bmim][Tf2N]-SO2 was Chemisorption while, in [Bmim]Tf2N]-CO2 was physisorption. Regarding the intermolecular interaction, the ion pair [Bmim][Tf2N]-SO2 was stronger than [Bmim][Tf2N]-CO2. Likewise, the ion pairs [Emim][Ac]-SO2 interaction was stronger than [Emim][Ac]-CO2 and the interactions among the molecules in [Emim][Ac]-SO2 was also stronger than that of [Emim][Ac]-CO2. Hence, [Bmim][Tf2N] and [Emim][Ac] seems to be the most suitable option to capture SO2 gas relative to CO2. The HOMO-LUMO gap for [Bmim][Tf2N]-SO2 was the highest showed that highest chemical hardness and the most stable compound