This is an extended research of the paper (Islam et al., 2011) conducted to obtain a universal set of interaction parameters of the model NRTL over the temperature range 10 - 100 °C for hexane-butanol-water system; meaning for binary pairs hexane-butanol, butanol-water and hexane-water; and for ternary system hexane-butanol-water. Thorough investigations of data selections for all binary pairs (Vapor-Liquid Equilibrium (VLE), Liquid-Liquid Equilibrium (LLE)), infinite dilution activity coefficient (γ∞), infinite dilution distribution coefficient (Dsw), excess enthalpy (HE), and for ternary system (LLE of hexane-butanol-water) were carried out. Finally quadratic temperature dependent interaction parameters were estimated regressing all the mentioned data and in each case calculated results were compared with literature values. The comparisons showed an overall percentage of error within 15% for the mentioned phase equilibrium calculations.