Abstract: A process for producing tertiary amine-sulphur trioxide complexes of the general formulaR.sub.3 N:SO.sub.3where R is a either methyl, ethyl, or propyl or the group R.sub.3 N is pyridyl comprising forming a reaction mixture of chlorosulfonic acid, pyridine or other tertiary amine R.sub.3 N, where R is previously defined and a chlorinated organic solvent. Gaseous ammonia is passed into the reaction mixture in order to recover amine from amine hydrochloride which is formed as a by-product of the reaction. Since the amine is more soluble in the chlorinated solvent than ammonium chloride that is co-produced, the reaction of the amine with chlorosulfonic acid to produce R.sub.3 N:SO.sub.3 is favored.