Abstract: Metal foam is a kind of porous material with good heat transfer performance. The application of metal foam as a wick is expected to improve the heat transfer performance of heat pipes. A sodium heat pipe with a metal-foam wick was developed, and its start-up performance and isothermal performance were experimentally studied and compared to a wickless sodium heat pipe. The results show that the lowest heating temperature needed for successfully starting up a sodium heat pipe with a metal-foam wick is lower than that of a wickless sodium heat pipe. Also, the start-up time of the metal-foam wick sodium heat pipe is shorter than the wickless one at the same heating temperature. Meanwhile, the start-up time of the sodium heat pipe decreases with the increase in heating temperature, and the axial temperature distribution becomes more uniform. The start-up performance and isothermal performance of sodium heat pipe with metal-foam wick appeared to be better than the wickless one. The advantages of using a metal foam as a wick for high-temperature heat pipes are preliminarily proved by experimental research.