Shape-stabilized phase change material (PCM) is a kind of novel thermal energy storage material. Its thermal conductivity is low, which limits its application in many conditions. In this paper, additives with high thermal conductivities were doped in it to improve its thermal conductivity. The thermal conductivity was measured by a thermal probe at room temperature. The experimental results show that the thermal conductivity of the shape-stabilized PCM can be improved greatly by adding exfoliated graphite. An empirical equation was developed for calculating the effective thermal conductivity of the shape-stabilized PCM with different mass fraction of graphite additive. By using the so-called numerical element method, a theoretical equation was obtained for predicting the effective thermal conductivity, which agrees well with the experimental results. The empirical equation and the theoretical prediction are useful for "designing" and controlling the thermal conductivity of the shape-stabilized PCM. (c) 2005 Elsevier B.V. All rights reserved.