The esterification of acetic acid and 1-hexanol to produce hexyl acetate and water is a test system for modeling and simulation as well as design and scale-up of reactive distillation. The present work provides a complete, high-quality phase equilibrium database for that task. The available literature data were critically surveyed, and existing gaps were closed by experimental work. Vapor-liquid equilibria were studied in isobaric and isothermal experiments for the binary systems acetic acid + 1-hexanol, acetic acid + hexyl acetate, and 1-hexanol + hexyl acetate at pressures between (30 and 90) kPa, corresponding to temperatures between (355 and 440) K. Liquid-liquid equilibria were studied in the systems water + 1-hexanol, water + hexyl acetate, water + acetic acid + 1-hexanol, and water + acetic acid + hexyl acetate at temperatures between (280 and 355) K. On the basis of that data, two parameter sets for the NRTL model were determined, one for the description of vapor-liquid and one for liquid-liquid equilibria. Vapor-liquid and liquid-liquid equilibrium experiments in the quaternary system water + acetic acid + 1-hexanol + hexyl acetate were carried out and used for testing the models. The new database allows the reliable process simulation of hexyl acetate reactive distillation.