A two-dimensional numerical simulation of the melting process in a rectangular enclosure for different inclination angles, has been carried out. Galium as a phase change material (PCM) with low Prandtl number is used. A numerical code is developed using an unstructured mesh, finite-volume method and an enthalpy porosity technique to solve for natural convection coupled to solid–liquid phase change. The validity of the numerical code used is ascertained by comparing our results with previously published results. The effect of the inclination angle on the flow structure and heat transfer characteristics is investigated in detail. It is found that the melting rate inside the rectangular cavity increases by decreasing the inclination angle from 90° to 0°