Tetrabutylammonium hydroxide is widely used as a phase-transfer catalyst in organic synthesis, facilitating reactions between compounds in different phases, such as aqueous and organic layers. It is particularly effective in nucleophilic substitution reactions, where it enhances the reactivity of anions in organic solvents. In analytical chemistry, it serves as an ion-pairing agent in chromatography, improving the separation of ionic compounds. Additionally, it is employed in the preparation of siloxanes and other organosilicon compounds, where it acts as a strong base. Its use in electrochemical applications includes functioning as an electrolyte additive in batteries and fuel cells to optimize performance.