The phase equilibria of aromatics separation from the multicomponent system [paraffins: (tetradecane + hexadecane + heptadecane) and aromatics (ethylbenzene + 1,3,5-trimethylbenzene + butylbenzene)] using N-methyl-2-pyrrolidone (NMP), as an extracting agent, have been studied. The aromatics in the multicomponent mixture were extracted at different temperatures (293-323 K) and different solvent to feed ratios (0.99-1.89). Such a system is found in the removal of aromatics from middle distillates in petroleum processing. The effects of temperature, solute concentration in the feed, and solvent to feed ratio on solubility, distribution coefficient, selectivity, and yield were investigated. The abilities of nonrandom two liquid (NRTL) and universal quasi-chemical (UNIQUAC) models to predict liquid-liquid equilibria were evaluated. The experimental data of the studied system were regressed to estimate the interaction parameters between each of the seven pairs of components using the two models as a function of temperature. The calculated results were comparable with the experimental data. Minimum major cost parameters and maximum yield of operation were analyzed through an optimization model to investigate the effects of temperature and solvent to feed ratio. Optimum operating conditions for enhanced aromatic extraction were unveiled.