Abstract The interaction between laminar Rayleigh–Benard convection and non-isothermal melting process is studied for the case of ice slurry kept in a rectangular cavity heated from the bottom. Clear visualization of the Rayleigh–Benard convective cells and their interaction with the melting front are obtained. It is observed that the convective cells are characterized by zones of up-flow and down-flow, resulting in the development of a nonplanar interface. Because of the continuous advancement of the solid/liquid interface, the effective solid height of the cavity keeps decreasing. The results include also the evolution of the solid–liquid interface, the local temperature and the ice mass fraction inside the storage tank.