Used as a phase-transfer catalyst in organic synthesis, facilitating reactions between reagents in different phases by transferring ions into organic solvents. Employed in the preparation of fine chemicals and pharmaceuticals where mild and selective reaction conditions are required. Also applied in electrochemistry as a supporting electrolyte due to its good solubility and stability in polar solvents. Its hydrated form helps improve handling and solubility in aqueous systems. Additionally, the tetraethylammonium cation serves as a potassium channel blocker in biological and pharmacological research, particularly for studying ion channels in nerve and muscle cells, enabling clearer investigation of bioelectric cellular functions.