Isothermal vapor-liquid equilibrium (VLE) data were measured for the hexane + pentan-2-one/4-methylpentan-2-one systems to characterize the separation limits. Phase equilibrium measurements were undertaken at approximately 313, 323, and 334 K at subatmospheric pressures using a dynamic apparatus. The gamma-Phi regression approach was used with the nonrandom two-liquid or UNIQUAC activity coefficient models employed to account for the nonideality of the liquid phase, with the Hayden and O'Connell correlation in the virial equation of state, used to account for the vapor phase nonideality. Additionally, the data were modeled by the phi-phi approach with the Peng-Robinson and perturbed-chain statistical associating fluid theory equations of state, which exhibited an inferior performance in comparison to the modeling by the gamma-Phi. approach. The area and point thermodynamic consistency tests were applied to the data and showed that the measured data were thermodynamically consistent. Excess enthalpy predictions were found to correlate well with the available literature.