The new asymmetric water-soluble phosphine (S)-(−)-(3-diphenylphosphino-2-hydroxypropyl)trimethylammonium chloride was synthesised from the accessible (S)-(−)-(3-chloro-2-hydroxypropyl)trimethylammonium chloride by means of a one pot reaction between this ionic compound and sodium diphenylphosphide in liquid ammonia. The palladium complex (L)PdCl3 (L = (S)-(−)-(3-diphenylphosphino-2-hydroxypropyl)trimethylammonium) was prepared by reaction between this ligand and PdCl2(PhCN)2 and was characterised by spectroscopic methods.