Abstract This paper presents an experimental investigation of the solid–liquid phase change process of three natural paraffin waxes, which show slightly different melting temperature: 53 °C, 57 °C, and 59 °C, at three heat fluxes: 6.25, 12.5, and 18.75 kW m −2 . Furthermore, the use of copper foams to improve the phase change process is experimentally studied by employing three different samples with 5, 10, and 40 PPI and constant porosity equal to 0.95. The experimental results clearly show that the presence of the foam matrix improves the heat transfer capabilities of the passive system allowing for lower surface temperature compared to no-foam case, at the same imposed heat flux. A direct video visualization of the process also permitted to show the effects of the porous medium on melting and solidification processes.