The heat transfer behaviour of a latent heat store is a key aspect influencing its utility in practical applications. With this in view, the present paper describes experimental investigations undertaken to determine the thermal performance characteristics of a prototype latent heat storage module employing a finned heat-pipe heat exchanger and filled with a fatty acid as the heat storage material. Results obtained from measurements during charging of the latent heat store, including the influence of major operating parameters on the thermal response of the store, are discussed in detail in the first part of the paper. The store thermal behaviour during two other operation modes of storage discharging and bypass is then briefly described. Finally, the modular feature of the storage concept is examined by comparing the heat transfer characteristics during charging of a single module with that during discharging of a 4-module latent heat storage unit.