Experimental densities, speeds of sound and refractive indices of the binary mixtures of ethanol with MMIM MeSO4 (1,3-dimethylimidazolium methyl sulfate), BMIM MeSO4 (1-butyl-3-methylimidazoliuin methyl sulfate), BMIM PF6 (1-butyl-3-methylimidazolium hexafluorophosphate), HMIM PF6 (1-hexyl-3-methylimidazolium hexafluorophosphate) and OMIM PF6 (1-methyl-3-octylimidazolium hexafluorophosphate) were determined from T= (293.15 to 303.15) K. Excess molar volumes, changes of refractive index on mixing and deviations in isentropic compressibility for the above systems were calculated. The (liquid + liquid) equilibrium (LLE) data of (IL + ethanol) were carried out experimentally and the NRTL and UNIQUAC correlative equation was applied to these mixtures. (c) 2006 Elsevier Ltd. All rights reserved.