Phase change material PCM is a promising strategy for reducing energy consumption in various applications. Among the large number of PCMs studied in the literature, paraffin are considered to be promising for latent heat thermal energy storage LHTES due to its appropriate thermal properties and their chemical stability. The interest of this work is to carry out an experimental procedure to visualize the phase change process of paraffin in a square cavity at different inclination angles. This article reveals how the melting rate could be affected by changing three orientations 90° (vertical heating), 0° (bottom horizontal heating) and 45° (inclined heating). The enclosure is heated on one side while the other walls are thermally insulated. The numerical photos, infrared thermal image and thermocouples-temperatures recorded during the melting processing are used to calculate the melting fractions and to estimate the intensity of heat transfer in different angles. The results show that the inclination angle has a great influence on the behavior of natural convection, affecting the front melting propagation and heat transfer rate. When the inclination angle decreases from 90° to 0° the convection currents in the cavity progressively evolve from a dominant single-cell movement to an unstable Rayleigh-Benard movement. The total melting time for the bottom and inclined heating cavities were, on average, 56% and 45% less than that of the vertical heating, respectively.