Isothermal liquid-liquid equilibria were measured for the water-n-butanol-n-hexane system at 313.15 K. Isobaric vapor-liquid (VLE) and vapor-liquid-liquid equilibria (VLLE) were measured for the same system at normal atmospheric pressure using an all-glass dynamic recirculating still with an ultrasonic homogenizer coupled to the boiling flask. The experimental LLE, VLE and VLLE data were found to be thermodynamically consistent. The data was correlated using the NRTL and UNIQUAC models and predicted by means of UNIFAC. The parameters set thus obtained reproduces the LLE experimental data appropriately. However, it has been difficult to correlate the VLLE data and only the NRTL model produces an acceptable solution. (C) 2011 Elsevier B.V. All rights reserved.