High-pressure volumetric properties of ionic liquids: 1-butyl-3-methylimidazolium tetrafluoroborate, [C4mim][BF4], 1-butyl-3-methylimidazolium methylsulfate [C4mim][MeSO4] and 1-ethyl-3-methylimidazolium ethylsulfate, [C2mim][EtSO4]

► High-pressure density of IL have been measured. ► Density measurements were performed using a vibrating tube densimeter. ► Measurements have been taken over (283.15 to 353.15) K and the (0.1 to 35) MPa. ► Experimental densities have been correlated by the Tait. ► α and κ of ILs as a function of temperature and pressure have been calculated.