Using the available interaction parameters for organic carbonate + alkane mixtures, the ability of the. DISQUAC, and modified UNIFAC group contribution model to predict solid-liquid equilibria (SLE). and liquid-liquid equilibria (LLE) is investigated. Six sets of the SLE and LLE temperatures for dimethyl carbonate + n-alkane (octadecane,,eicosane, docosane, tetracosane, hexacosane, and octacosane) systems have been measured by a dynamic method from 278.65 K to the; melting point of the long-chain n-alkane and to the upper critical temperature of two coexisting phases. The SLE data have been correlated by three equations: Wilson, UNIQUAC, and NRTL. The existence of a solid-solid first-order phase transition in n-alkanes has been taken into consideration in the solubility calculations. The relative standard deviations of the solubility temperature correlation for all measured data vary from 0.2 to 1.3 K and depend on the particular equation used. The LLE coexistence curves' are very asymmetrical with respect to mole fraction, with the asymmetry increasing with the size of the n-alkane. The critical solution points vary almost linearly with the number of carbon atoms of the n-alkane. The SLE curves are usually well predicted by DISQUAC and modified UNIFAC models with an average standard deviation of less than 1.6 K.