It is commonly used in chemical synthesis as a phase-transfer catalyst and as a reagent in organic reactions especially where ionic interactions are required.

Its main purpose is to facilitate reactions between compounds in different phases (such as organic and aqueous) and to enhance reaction efficiency by improving the transfer of reactive species.

Tetramethylammonium bisulfate is a quaternary ammonium salt composed of a tetramethylammonium cation and a bisulfate anion typically appearing as a crystalline solid that is soluble in water and polar solvents.