Methyltrioctylammonium hydrogen sulfate is a quaternary ammonium salt primarily employed as an extraction solvent and phase transfer catalyst in various chemical reactions. It serves as an electrolyte in electrochemical devices such as batteries and fuel cells, and as a foundational material for synthesizing pharmaceuticals and agrochemicals. MTOAHS is a versatile compound due to its reactivity, stability, and ability to selectively extract specific compounds from mixtures, offering numerous potential industrial applications.