Glycerin is an important by-product in biodiesel production. To increase its quality to be suitable for use it in other operations, e.g., the pharmaceutical industry, it needs to be purified. Therefore, the purification of glycerin by liquid-liquid extraction of methanol using different solvents was investigated. It was shown that, in terms of separation, petroleum ether was more effective than toluene and toluene was more effective than n-butanol. In addition to the experimental investigations, the NRTL and UNIQUAC thermodynamic models were used to predict the compositions of ternary mixtures of glycerin + methanol + organic solvent in glycerin-rich and organic solvent-rich phases. The results showed the high accuracy of the presented models and their consistency with the measured data.