Ammonium tetrachloroaurate, also known as gold ammonium chloride, is a compound used in various applications in chemistry and materials science. It is commonly utilized as a precursor for the synthesis of gold nanoparticles, which have applications in fields such as nanotechnology, biomedical research, and catalysis. Additionally, it is employed in the preparation of solutions for gold plating, a process used to coat objects with a thin layer of gold for decorative or functional purposes. Ammonium tetrachloroaurate also finds use in chemical analysis, particularly in the detection and quantification of certain compounds.