Liquid-liquid phase equilibrium (LLE) data have been measured for the ternary system 2-butanone + 2-butanol + water at (293.25, 313.15, 323.15, and 333.15) K. Experimental results show the extreme phase sensitivity of this system to temperature. At (293.15 and 313.15) K the ternary system has two separate biphasic regions, while at (323.15 and 333.15) K the system has only one region of immiscibility. The nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) models were applied to correlate the ternary system at (323.15 and 333.15) K; the interaction parameters obtained from both models successfully correlated the equilibrium compositions. Moreover, isobaric vapor-liquid-liquid equilibrium (VLLE) is measured for this ternary mixture at 101.3 kPa. The experimental data were compared with the estimation from LLE binary interaction parameters using NRTL and UNIQUAC models and with the prediction of universal functional activity coefficient (UNIFAC) model.