This paper reports basic heat transfer data during melting of n-octadecane from an isothermal vertical wall of a rectangular cavity. The shadowgraph technique was used to measure local heat transfr coefficents at the heat source surface and the solid-liquid interface motion during phase change was recorded photographically. Experimental results clearly showed that, except in the very early stages of melting, the rates of melting and of heat transfer were greatly affected by the buoyancy-driven convection in the liquid. Initial subcooling of the solid substanially impeded the phase change process. A numerical simulation of the corresponding two-dimensional melting in the presence of natural convection was performed, and the numerical predictions are compared with experimental data.