In this paper, a thermodynamic model based on solid solution model is developed to predict the solid–liquid equilibrium (SLE) of certain binary and multi component mixtures (paraffinic) in atmospheric pressure to very high pressure. In this approach, the solid phase activity coefficient is calculated by Wilson activity coefficient model. The fugacity coefficient in liquid phase is calculated by the NB and PR equations of state using van der Waals mixing rules. Appropriate binary interaction parameters from Jaubert et al. are used with the van der Waals mixing rules to characterize the liquid phase more accurately. The developed model describes the SLE of hydrocarbon systems quite well from low to high pressures. This model is capable of predicting wax formation temperature for a vast range of pressures. The predictions of the developed model are favorably compared to the experimental data.