Isothermal vapour-liquid equilibrium data, (VLE) have been measured by an ebulliometric method for four binary mixtures of N-methyl-2pyrrolidinone (NMP) with dipropyl ether at T= 353.15 K and T= 373.15 K, or dibutyl ether at T= 373.15 K, or methyl 1, 1-dimethylethyl ether (MTBE) at T= 333.15 K, or methyl 1, 1 -dimethylpropyl ether (MTAE) at T= 353.15 K, in the pressure range from P = 0 kPa to P = 135 kPa. The experimental VLE results have been correlated using a three parameter Redlich-Kister expansion. All these systems present positive deviations from Raoult's law. Binary mixtures of NMP with dipropyl ether, dibutyl ether, MTBE and MTAE have been investigated in the framework of the Modified UNIFAC (Do) and DISQUAC models. The reported new interaction parameters for the NMP-group (N-CO) and the ether group (-O-) give much better results than known from literature predictions of the thermodynamic properties, including vapour-liquid equilibrium, excess molar Gibbs energy, molar excess enthalpies and solid-liquid equilibrium. Our experimental data and literature data for binary mixtures containing NMP and ethers were compared to the results of predictions with the Mod. UNIFAC (Do) and DISQUAC models. (c) 2005 Elsevier B.V. All rights reserved.