Liquid-liquid equilibrium phase diagrams for two binary systems: water + l-pentanol and water + 2-methyl-2-butanol and two ternary systems: water + 1-pentanol + 2-butyloxyethanol and water + 2-methyl-2-butanol + 2-butyloxyethanol at 20 degrees C and 30 degrees C are presented in this paper. The experimental results were correlated with the UNIQUAC model by fitting the effective UNIQUAC binary interaction parameters as a function of temperature. Agreement between the calculated and experimental data was very good.