The limited capacity of insertion materials due to their structure, as well as the decohesion phenomena of the Li-alloying materials due to the huge volume change, have attracted the attention toward a new type of electrochemical reactivity, which emerged in these last few years: the so-called conversion mechanism. The conversion reaction of metal oxides and sulfides are good candidates as anode materials for Li-ion and Na-ion batteries because they offer high specific capacity. This book describes the synthesis, characterization, and studies on electrochemical behavior w.r.t lithium and sodium based conversion reactions of certain ternary molybdates oxides, ternary iron oxides, and ternary sulfides as anode materials for Li-ion and Na-ion batteries.