Liquid-liquid equilibrium (LLE) data were experimentally determined and correlated for the aqueous solutions of a series of carboxylic acids (i.e. formic, acetic, propionic, and butyric acids) with ethylbenzene at a temperature of 298.15 K and p = 101.32 kPa. The ternary mixtures containing of the acids exhibit type-1 LLE behavior. The quality of the observed tie-lines was checked using: the Othmer-Tobias equation. The correlations were Carried out using the thermodynamic and statistical modeling. The activity coefficient, models of UNIQUAC and NRTL were applied to fit the tie lines and values of the binary interaction parameters between each pair of components were obtained. The correlation of the tie lines was also carried out by a GMDH type-NN, which are in agreement with those obtained experimentally. In this Work, experimental distribution coefficients and separation factors were estimated. Moreover, the Kamlet-Taft LSER model was employed to correlate these quantities and was interpreted in terms of intermolecular interactions.