Ionic liquids (ILs) are eco-friendly solvents due to their low vapor pressure. Properties such as density should be known as it affects the mass transfer rates. Due to its limitless combinations, it is impractical to measure densities experimentally. For the first time, the cohesion factor in the cubic equations of state (CEOS) is used to predict the densities of six commercial ILs, namely, 1-ethyl-3-methylimidazolium methane sulfonateTris(2-hydroxyethyl)-methylammonium methyl sulfate [TEMA][MeSO 4 ], and trihexyl(tetradecyl) phosphonium bis(2,4,4-trimethylpentyl) phosphinate [TDTHP] [Phosph]. CEOS models such as predictive Soave−Redlich−Kwong (PSRK) coupled with cohesion factor gave better results when compared to the correlations such as Reid et al. (RR), Mchaweh et al. (MH), and the linear generalized model (LGM). In this work the PSRK equation of state (EOS) with the derived NSM1 alpha function and PSRK with original SRK alpha function were used for the prediction. PSRK EOS model with NSM1 alpha function and PSRK EOS with original SRK alpha function proved very accurate with average minimum deviation of 0.02 % to 0.44 % and 0.29 % to 0.66 % from experimental values for six ILs, respectively.