The (vapour + liquid) equilibrium (VLE) and boiling temperature measurements have been determined at 95.3 kPa as a function of composition for the binary liquid mixtures of N-methyl-2-pyrrolidone (NMP) with branched alcohols using a Swietoslawski-ebulliometer. The branched alcohols include 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and 3-methyl-1-butanol. The experimental temperature-composition (T-x) results were used to estimate Wilson parameters and then used to calculate the equilibrium vapour compositions and the excess Gibbs free energy at T = 298.15 K. The experimental temperature-composition (T,x) results were correlated with the Wilson, the NRTL and the UNIQUAC models. The experimental results are interpreted in terms of intermolecular interactions between constituent molecules. (C) 2008 Elsevier Ltd. All rights reserved.