Abstract: The compatibility of Ba(OH)₂·8H₂O with aluminum alloy and copper was studied by SEM and X ray energy dispersive spectrometer analysis methods after 50 thermal cycles. Results show that Ba(OH)₂·8H₂O displays a certain amount of corrosion in combination with aluminum alloy. Ba(OH)₂·8H₂O and copper present excellent compatibility. A simple method of successive vacuum absorption and padding was employed to prepare Ba(OH)₂·8H₂O/copper foam phase change composites. An experimental setup was built to study the heat transfer performances of Ba(OH)₂·8H₂O with and without copper foams. The steady state and transient heat transfer performances of Ba(OH)₂·8H₂O/copper foam composites were experimentally measured at room temperature. The results show that Ba(OH)₂·8H₂O/copper foam phase change composites have higher heat transfer rate, better heat transfer performance and lower supercooling degree than the pure Ba(OH)₂·8H₂O. The heat transfer experiments indicate that the thermal storage capacity of the composites decreases with the increase of ambient temperature in the high-temperature thermotank. When the ambient temperature is higher than the phase change temperature, some insulation measures should be considered for the phase change composites.