Lithium aluminum deuteride is a substance in which the hydrogen ions in lithium aluminum hydride are replaced by deuterium, which is composed of hydrogen isotope deuterium and lithium aluminum. Its chemical formula is LiAlD4. It is a white to yellow odorless crystalline solid, hygroscopic and soluble in methanol and ether. Lithium aluminum deuteride is mainly used in deuteration reactions in organic synthesis. It can be used as a deuteration agent to replace hydrogen atoms in carbonyl compounds with deuterium atoms to study reaction kinetics or trace reaction paths. In addition, lithium aluminum deuteride is also used as a hydrogen source and a compound of deuterium sources, which can replace hydrogen in some chemical reactions and be used to synthesize some organic compounds. It is also commonly used in the study and preparation of hydride materials.