A water-soluble monoazo compound of the formula ##STR118## in which D is phenyl or naphthyl and both are substituted by 1, 2 or 3 substituents selected from the set consisting of three sulfo, two carboxy, two alkyl of 1 to 4 C-atoms, two alkoxy of 1 to 4 C-atoms, one bromine, two chlorine and two groups of the formula --SO.sub.2 --Z in which Z is .beta.-hydroxyethyl or a group Y of the meaning indicated below,
- R is carboxy,
- R.sup.1, R.sup.2 and R.sup.3 are identical to or different from one another and
- R.sup.1 is hydrogen or alkyl of 1 to 4 C-atoms,
- R.sup.2 is hydrogen, alkyl of 1 to 4 C-atoms, alkoxy of 1 to 4 C-atoms or chlorine,
- R.sup.3 is hydrogen, alkyl of 1 to 4 C-atoms or alkoxy of 1 to 4 C-atoms,
- Y is vinyl or ethyl substituted in the .beta.-position by a substituent which is eliminated as an anion under alkaline conditions, and
- Hal is chlorine.