In this study, the performances of Peng-Robinson Equation of State combined with the classical mixing rules were evaluated to calculate solid-vapor equilibrium (SVE) and solid-liquid equilibrium (SLE) of CH 4 -CO 2 system. The evaluation was performed by comparing the calculated values with the literature data. In the calculation of SVE, the new binary interaction parameter values (k ij ) of CH 4 -CO 2 mixtures were proposed in this work based on the experimental data. The proposed k ij obtained in this work might increase the accuracy of Peng-Robinson Equation of State by reducing average absolute deviation in the temperatures between calculated values and literature data from (2.18% to 0.26%), (0.88% to 0.70%) and (0.61% to 0.44%) at CO 2 composition of 1%, 1.91% and 2.93%, respectively. Significant improvement was found at CO 2 composition of 1%. In the calculation of SLE, new parameters were not proposed since the calculation using the existing (literature) k ij gives good results with an average absolute deviation of 0.5%.