In this work, the isobaric vapor-liquid equilibrium (VLE) data obtained for the ternary system water + HCl + ethanol at 78 kPa, using an Ellis still, were studied. Two rigorous electrolyte models (extended UNIQUAC and LIQUAC) were fitted to the experimental data. Ethanol-H+, water-H+, ethanol-Cl-, water-Cl-, and Cl--H+ interaction parameters were determined. Likewise, Henry's law constants for the volatile electrolyte were defined. A high goodness of fit was obtained for both electrolyte models; however, the extended UNIQUAC one showed better performance (AAD = 0.1326%). Two azeotropes observed in the system were accurately predicted (ethanol + water: X-EtOH = 0.86 at 344.6 K; and HCl + water: X-HCl = 0.11 at 375.5 K). (c) 2017 Elsevier Ltd.