N1,N1,N1,N6,N6,N6-Hexamethylhexane-1,6-diaminium chloride dihydrate (hexamethonium chloride dihydrate) is a bis-quaternary ammonium salt. It is primarily used in pharmacological and biomedical research as a ganglionic blocking agent, antagonizing nicotinic acetylcholine receptors at autonomic ganglia to inhibit sympathetic and parasympathetic neurotransmission. This property makes it valuable for studying autonomic nervous system functions and as a tool in experimental hypertension models. In synthetic chemistry, it serves as a phase-transfer catalyst to enhance reactions between immiscible phases. Its cationic nature also enables applications as a surfactant, antimicrobial agent, and in formulation of ionic liquids or electrolytes.