Vapor pressure data were measured for water, methanol and ethanol as well as their binary mixtures with an ionic liquid (IL) 1-ethyl-3methylimidazolium dimethylphosphate ([EMIM][DMPI) at varying temperature and IL-content ranging from mass fraction of 0.10-0.70 by a quasi-static method. The vapor pressure data for the IL-containing binary systems were correlated using NRTL equation with average absolute relative deviation (ARD) within 0.0076, and the binary NRTL parameters was used for predicting the vapor pressure of the IL-containing ternary systems with reasonable accuracy. In addition, the infinite activity coefficients of solvents in [EMIM] [DMP] and isobaric vapor-liquid equilibrium for EL-containing ternary systems at 101.325 kPa. and mass fraction of IL being 0.5 were predicted with the regressed NRTL parameters. The results indicate that ionic liquid [EMIM][DMP] can depress the volatility of the solvents of water, methanol and ethanol but to a varying degree, leading to the variation of relative volatility of a solvent and even removal of azeotrope for water-ethanol mixture. (c) 2007 Elsevier B.V. All rights reserved.