In an attempt to increase the heat transfer rate and reduce the convective currents during freezing in PCM storage tank, externally finned circular tubes submersed in PCM were studied both theoretically and experimentally. The analytical formulation of the problem was done by applying control volume technique to the enthalpy formulation of the phase change problem controlled by conduction. The equation obtained is applicable to the phase change material in the solid, liquid phase as well as to the metallic fins. Numerical calculations were done using ADI approach for finned and for one- dimensional unfinned cylinder. The parameters analyzed include: number of fins, fin length, fin width, compactness ratio and degree of superheat. An experimental rig was designed and instrumented to permit comparing with the numerical results and establish the validity of the model proposed. The numerical results were found to agree well with experiments. 281292