The system urea-sodium acetate trihydrate has been mentioned in the literature as an energy storage system. Due to its low melting point (30degreesC), the system is not suitable for use in a hot climate. Modifying the system composition is shown in the present work through adding lead acetate trihydrate to the binary mixture in the ratio of 16.6% with the object of raising its melting point to a practical value. A melting point of 44.5degreesC could be reached for the new system. The mixtures of urea-sodium acetate trihydrate and urea-sodium acetate trihydrate-lead acetate trihydrate are tested in the present work as phase change storage mixtures and comparison between both mixtures was carried out. The results showed that the system composed of urea-sodium acetate-lead acetate stored 286 kJ/kg of the storage mixture. (C) 2003 Published by Elsevier Science Ltd.