Although metal alloys and intermetallic compounds have been researched extensively as possible negative electrodes for lithium batteries, only recently have efforts been made to monitor the phase transitions that occur during their reaction with lithium by in situ X-ray diffraction. These studies have lead to attempts to exploit those systems that show strong structural relationships between a parent structure and its lithiated products. In this paper, an overview of several systems is presented, particularly those that operate by lithium insertion/metal displacement reactions with a host metal array at room temperature. An analogy between these reactions and the high-temperature electrochemical reaction of sodium/nickel chloride cells, which is 100% efficient, is provided. On this basis, a prognosis for using intermetallic electrodes in lithium-ion cells is given.