The invention comprises monoazo dyes of formula <FORM:0826405/IV(c)/1> wherein the benzene nucleus X may be substituted but is free from hydroxy groups in all positions and from carboxyl groups ortho to the azo group, the benzene nucleus Z may be substituted other than by hydroxyl groups, Y is a methyl, carboalkoxy or carboxyl group, the dichloro-s-triazinylamino group is attached to X in meta- or para-position to the azo group or to Z in meta- or para-position to the nitrogen atom of the pyrazolone ring and the molecule contains at least two carboxyl and/or sulphonic acid groups. The dyes are prepared by reacting at least one molecular proportion of cyanuric chloride with a monoaminoazo compound of formula <FORM:0826405/IV(c)/2> wherein the amino group is attached to the nuclei X and Z in the way defined for the dichloro-s-triazinylamino group above and Y and the substituents in X and Z and the final product are as defined above. Alternatively the dyes are prepared by coupling a diazonium compound of the benzene series with a 1-phenyl-3 - methyl -, carboalkoxy - or carboxy - 5-pyrazolone wherein either the diazonium compound or the pyrazolone contains in the benzene ring, in meta- or para-position to the attached nitrogen atom, a 4 : 6 - dichloro - s - triazin - 2-ylamino group and the diazonium and pyrazolone components are so chosen that the final product is substituted as defined above. The aminoazo compounds of formula II wherein the amino group is in the nucleus X are prepared by diazotizing a suitable monoamine of the benzene series containing a nitro or acylamino group meta or para to the amino group, coupling with a 1-phenyl-3-methyl, carboalkoxy- or carboxy-5-pyrazolone free from hydroxyl, amino, nitro or acylamino groups and reducing the nitro group or hydrolysing the acylamino group of the resultant monoazo dye, the final product having at least two carboxyl and/or sulphonic acid groups. Specified components are: m- or p-nitroaniline, 3-nitroaniline - 6 - sulphonic acid, m - or p - aminoacetanilide, 4 - or 3 - aminoacetanilide - 3 or 4 - sulphonic acid and 4 - amino - 2 - acettoluidide - 5 - sulphonic acid; 1 - (61 - chloro - 31-methyl - 41 - sulphophenyl) - or - (41 - chloro-21 - sulphophenyl) - or - (21 - chloro - 41-methyl - 51 - sulphophenyl) - or (41 - methyl-21 - sulphophenyl) - or - (21:51 - or 31 : 51 - disulphophenyl) - or - (41 - ethoxy - 21 - sulphophenyl) - or - (21:41 - dichloro - 51 - sulphophenyl) - or - (61 - chloro - 31 - sulpho - 21-methylphenyl) - or (31 - or 41 - carboxyphenyl)-3 - methyl - 5 - pyrazolone, 1 - (61 - chloro - 41-sulpho - 21 - methylphenyl) - 3 - carboethoxy-5 - pyrazolone and 1 - (41 - sulphophenyl) - or - phenyl - or - p - tolyl - 3 - carboxy - 5-pyrazolone. The aminoazo compounds of formula II wherein the amino group is in the nucleus are prepared by coupling a suitable amine of the benzene series with a 1-(31- or 41 aminophenyl) - 3 - methyl, carboalkoxy - or carboxy - 5- pyrazolone, the final product having at least two carboxyl and/or sulphonic acid groups. Specified components are: orthanilic and sulphanilic acids, 4-methyl-2-sulphoaniline, 4- or 5-chloro-, 5- or 4-methyl-2-sulphoaniline, 5 - methoxy - 2 - sulphoaniline, and 2 : 5 - dichloro - 4 - sulphoaniline ; 1 - (31 - or 41-aminophenyl) - 3 - methyl -, carboxy - and carboethoxy - 5 - pyrazolones and 1 - (41-amino - 31 - carboxyphenyl) - 3 - methyl - 5-pyrazolone. The components used in the coupling method for the preparation of the compounds of formula I are prepared by reacting at least one molecular proportion of cyanuric chloride with a 1-(31- or 41-aminophenyl)-3-methyl, carboalkoxy- or carboxy-5-pyrazolone such as those specified above or a phenylene diamine such as 2-sulpho-1 : 4-phenylenediamine, 6 - sulpho - 1 : 3 - phenylenediamine and 2 : 4-diaminotoluene-5-sulphonic acid. The reaction of cyanuric chloride with amino compounds is preferably carried out in aqueous medium at between 0 DEG and 5 DEG C. and in the presence of an acid-binding agent such as sodium carbonate. The dyes are preferably isolated at a pH of 6-8 and dried at 20 DEG to 45 DEG C. in the presence of buffering agents such as mixtures of disodium hydrogen phosphate and sodium dihydrogen phosphate or of disodium hydrogen phosphate and potassium dihydrogen phosphate. The dyes may be used to colour silk, wool, regenerated protein, polyamide, polyacrylonitrile, cotton, linen and rayon in yellow to orange shades. In examples, cyanuric chloride is reacted with aminoazo compounds obtained from the following components with reduction of nitro groups or hydrolysis of acylamino groups where necessary, to give dyestuffs of formula I : diazo components: aniline - 2 : 5 - disulphonic acid, 4 - nitroaniline - 2 - sulphonic acid and 5-acetylamino - aniline - 2 - sulphonic acid; coupling components: 1 - (3 - aminophenyl)-or - (21 - methyl - 51 - sulphophenyl) - or - (21-or 41 - sulphophenyl) - or - (21:51 - dichloro-4 - sulphophenyl) - or - (61 - chloro - 41 - sulpho-21 - methylphenyl) - or - (21 - chloro - 51 - sulphenyl) - 3 - methyl - 5 - pyrazolone and 1 - (41-sulphophenyl) - 3 - carboxy - 5 - pyrazolone. Specifications 209,723, [Class 2 (iv)], 486,660, 515,066, [both in Group IV], and 797,946 are referred to.