Abstract: Water-soluble monoazo compounds of the general formula (1) ##STR1## in which D is a phenyl radical or naphthyl radical, either of which is substituted and mandatorily contains at least one group which imparts solubility in water and D is substituted, for example by 1, 2 or 3 substituents which can be selected from the set consisting of 1 sulfamoyl, 1 carbamoyl, 1 trifluoromethyl, 1 benzothiazol-2-yl, 1 sulfobenzothiazol-2-yl, 1 methylbenzothiazol-2-yl, 1 methylsulfobenzothiazol-2-yl, 1 styryl, 1 nitrostyryl, 1 sulfostyryl and 1 nitrosulfostyryl group and, preferably, three sulfo groups, two carboxy groups, two alkyl groups of 1-4 C atoms, two alkoxy groups of 1-4 C atoms, 1 bromine atom and two chlorine atoms and one or two groups of the formula --SO.sub.2 --Z with Z of the meaning below, and the group --SO.sub.2 --Z can also be bonded to one of the substituents and Z represents the .beta.