Corrosion of nickel, copper, and 316 stainless steel in aluminum chloride/1-ethyl-3-methylimidazolium chloride ionic liquid (IL) is investigated by means of electrochemical techniques. SEM analyses are performed to examine the reaction mechanisms. While Ni shows good stability, Cu has high corrosion susceptibility in this IL. For 316 steel, pitting corrosion occurs at a lower potential than that of passivation. In the non-aqueous, low-oxygen, and high-ion-containing IL, the material corrosion properties are totally different from those found in conventional environments. Since ILs have found increasing potential in diverse applications, new corrosion prevention strategies are needed to overcome the IL-derived material corrosion problems.