Capturing greenhouse gases and preventing climate change are becoming imperative global issues. There is a growing awareness that carbon dioxide emission from fossil fuel combustion is the biggest contributor to this environmental phenomenon. One of the most effective and potential solutions of reducing carbon dioxide emission is to capture it from industrial gas streams, such as flue gases. Among the most commonly used technologies, gas absorption via chemical solvent is the most promising technology due to its capacity to handle a large volume of carbon dioxide. Nevertheless, aqueous alkanolamines have shortcomings that make the process costly and environmentally unfriendly. Recently, ionic liquids started playing a significant role in overcoming these inadequacies. The main objective of this research is to determine the solubility of carbon dioxide in conventional ionic liquids. During this work, a gravimetric microbalance was used to measure the solubility of carbon dioxide in 1,3-Diethoxyimidazolium bis(trifluoromethylsulfonyl)imide [[(ETO)2IM][Tf2N]], 1,3Dimethoxyimidazolium bis(trifluoromethylsulfonyl)imide [[DMIM][Tf2N]], 1-Butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide [[BMPIP][Tf2N]], 1-Butyl-3-methylimidazolium trifluoromethanesulfonate [[BMIM][TfO]] and 1-Butyl-3 methylimidazolium dibutyl phosphate [([BMIM][DBP] ] at 298.15, 313.15 and 323.15 over a pressure range of 100 mbar to 20000 mbar. Critical properties of ionic liquids are estimated by group contribution methods, and estimated values were in agreement with published results. The Peng-Robinson (PR) equation of state and the nonrandom two-liquid (NRTL) models were used to correlate the experimental results. Consistency tests for obtained NRTL results are also presented.