Abstract: A process for the manufacture of stable, concentrated solutions of water-soluble tertiary ammonium salts of disazo dyestuffs is described, which comprises diazotizing 2 moles of the same primary aromatic amine or 1 mole each of different primary aromatic amines and reacting the diazo mixture with 1 mole of a compound which is able to couple with diazonium salt in at least 2 positions, in the presence of at least 2 moles of a tertiary amine and optionally other assistants. The resulting solutions prove stable even on prolonged storing at room temperature and are not affected by frost. The solutions are miscible in any ratio with water or, in part, also with suitable water-miscible organic solvents.