Vapour-liquid equilibrium data were measured for the propanoic acid + water system at 423.2,453.2 and 483.2 K from 1.87 to 19.38 bar over the entire range of concentrations. An experimental apparatus based on the static-analytical method with sampling of both phases was used with quantitative analysis by GC. The system is highly non-ideal showing azeotropic behaviour. The Peng-Robinson (PR), the cubic plus association (CPA), the perturbed chain statistical associating fluid theory (PC-SAFT) and the PC-polarSAFT (PCP-SAFT) equations of state modelled the data. Two association sites were assumed for both compounds. A single-binary interaction parameter (k(ij)) was used in all models, and predictive (k(ij) -= 0) and correlative (k(ij) = k(ij)(0) + k(ij)(1)T) capabilities were assessed. Available data at 313.1, 343.2 and 373.1 K from the open literature were included in the analysis. PCP-SAFT presented higher predictive and correlative capabilities over the entire temperature range. PC-SAFT in predictive mode was not able to represent the azeotropic behaviour but resulted in the second best correlations. CPA presented a satisfactory balance between the two modes. PR predictions were rather poor but correlations were better than those of CPA, at the expense of a larger k(ij). (C) 2015 Elsevier B.V. All rights reserved.