In this work, vapor-liquid equilibria (VLE) study for the systems (sucrose + 1-butyl-3-methyl imidazolium bromide + H2O) and {sucrose + 1-hexyl-3-methyl imidazolium bromide + H2O} in a wide range of concentrations has been carried out at 298.15 K and atmospheric pressure. To measure water activity, the improved isopiestic method was used. Vapor pressure and osmotic coefficient data of the solutions have been determined from the experimental measured water activity data. The performances of different local composition models such as Wilson, NRTL, modified NRTL, NRF-NRTL and UNIQUAC in the correlating the vapor-liquid equilibria data of these ternary systems have been investigated. Then, using the parameters obtained from these models, the unsymmetrical molal activity coefficients of the sucrose and ionic liquids in the binary and sucrose in ternary aqueous solutions have been calculated. The activity coefficient values were used to interpret the solute-solute and solute-solvent interactions presented in these systems. (C) 2016 Elsevier B.V. All rights reserved.