The invention comprises disazo dyestuffs of formula:-<FORM:0760347/IV(b)/1> where R1, R3 and Y are benzene residues, R1 having in para-position to the azo linkage a hydroxy group and in ortho position to the hydroxy group a carboxylic acid group, R3 being bound in the 1:2:4-position to the azo linkage, the carboxylic acid group and X, R2 is a benzene or naphthalene residue wherein the azo linkage and the bridge member X are in a para - position and X is an - NH - CO - NH - bridge or triazine residue bound to R2 and R3 by -NH- groups and copper complexes thereof. They are prepared by reacting the two aminoazo dyestuffs of formul : R1-N=N-R-NH2 (2) and <FORM:0760347/IV(b)/2> with phosgene, or by reacting a phenyl-urethane of one dyestuff with the other dyestuff or by means of a cyanuric halide to form the corresponding urea or triazine derivative, the final dyestuff (1) or the intermediate dyestuff (3) being treated with a copper-yielding agent if desired. The reaction with phosgene gives a mixture of dyestuffs, the asymmetrical derivative predominating. The asymmetrical derivative is formed alone when one of the aminoazo dyestuffs preferably of formula (3) is converted, by reaction with chloroformic acid phenyl ester, into the phenyl-urethane and the latter condensed with the other aminoazo dyestuff. The reaction of the aminoazo dyestuffs with a cyanuric halide, preferably cyanuric chloride, is advantageously carried out in stages the dyestuffs being condensed successively. The third halogen atom attached to the triazine ring may be replaced by a hydroxyl group or it may be further reacted e.g. with ammonia or aniline. Aminoazo dyestuffs of formula (3) are prepared by coupling a diazotized orthocarboxy-aminobenzene containing para to the amino group a substituent convertible to an amino group, with a 2-phenylamino-8 - hydroxynaphthalene - 6 - sulphonic acid which may contain in the phenyl residue further substituents such as chlorine atoms or methyl, methoxy, sulphonic acid, carboxylic acid or sulphonamide groups, and converting the aforesaid substituent into an amino group. Specified diazo components are 4-nitro-or-acetylamino-1-aminobenzene-2-carboxylic acid and specified coupling components are 2-phenylamino-8-hydroxy-naphthalene-6:31- or 6:41- disulphonic acid and 2 - phenylamino - 8 - hydroxynaphthalene - 6 - sulphonic acid - 31 - or - 41 - carboxylic acid. The aminoazo dyestuff of formula (2) may contain in R1 advantageously in ortho-position to the hydroxy group further substituents such as a halogen atom or a methyl or sulphonic acid group. The residue R2 may also contain substituents such as a halogen atom or a methyl, methoxy or sulphonamide group. Specified aminoazo dyestuffs of formula (2) are 4 - amino - 41 - hydroxy - 1:1 - azobenzene - 31 - carboxylic acid, 2 - chloro - 2 - methyl - 5 - methoxy -, 51 - sulpho - and 2 -methyl - 5 - methoxy - 51 - sulpho - 4 - amino - 41 - hydroxy - 1:11 - azobenzeneazobenzene - 31 - carboxylic acid and 4 - amino - 41 - hydroxybenzene - 11 - azo - 1 - naphthalene - 31 - carboxylic acid - 6 - or 7 - sulphonic acid. The dyestuffs form copper complexes in substance or on the fibre by known methods. The ortho - hydroxy-carboxy grouping is preferably not metallized but if during complex formation two or more atoms of copper are present per mole of dyestuff, coppering takes place at the ortho - hydroxy - carboxy group. Also, coppered dyestuffs which are not coppered at the hydroxy - carboxy grouping may be further coppered in the dye bath or on the fibre. Sparingly soluble coppered dyestuffs of the invention may be used in the dyeing processes described in Specification 732,925 and 737,800. The dyestuffs may be used for dyeing and printing wool, silk leather and especially fibres of natural or regenerated cellulose. They dye cellulose-containing fibres in brown tints. In examples: (1) the aminoazo dyestuff prepared by coupling diaotized 5 - acetylamino - 2 - aminobenzene-1-carboxylic acid with 2-phenylamino-8-hydroxynaphthalene - 6:31 - disulphonic acid and converting the acetylamine group to amino is mixed with 4-amino - 41 - hydroxy - 1:11 - azobenzene - 31 carboxylic acid or the 2 - chloro-derivative thereof, reacted with phosgene and the copper complex containing one atom of copper per molecule is prepared; (2) the aminoazo dyestuff prepared by reduction of the nitro group in 4-nitro-1-aminobenzene-2-carboxylic acid-->2-phenylamino-8-naphthol-6:31-disulphonic acid is reacted with cyanuric chloride the product is further reacted with 4-amino-41-hydroxy-1:11-azobenzene-31 -carboxylic acid and finally reacted with aniline to give the diazo dyestuff which is coppered; (3) 2 - chloro- - 4 - amino - 4 - hydroxy - 1:11 - azobenzene - 31 - carboxylic acid is reacted with chloroformic acid phenyl ester to give the corresponding phenyl-urethane which is further reacted with the dyestuff of formula (3) prepared as in (1); (4) as in (2) but reversing the order of condensation of the dyestuffs with cyanuric chloride and also using alternatively 2-phenylamino-8-naphthol-6-sulphonic acid-31- or 41-carboxylic acid in the preparation of the dyestuff of formula (3) and 2-chloro-4-amino-41-hydroxy-1:1 -azobenzene-31-carboxylic acid; (5) 4 - amino - 41 - hydroxy - 1 : 11 - azobenzene - 31 - carboxylic acid or the 2 - chloro - derivative thereof is condensed with cyanuric chloride and the product isolated and then reacted with the copper complex of a dyestuff of formula (3) wherein Y bears a sulphonic acid group in the 3-position; (6) cyanuric chloride is condensed first with 4-amino-41-hydroxy-1:11-azobenzene - 31 - carboxylic acid or the 2 - chloroderivative thereof and then with a dyestuff of formula (3) carrying no additional substituents and the resultant dyestuff isolated, the reaction of the third chlorine atom with aniline giving a similar dyestuff; (7) phosgene is reacted with a mixture of 4 - amino - 41 - hydroxy - 1:11 - azobenzene - 31-carboxylic acid and a dyestuff of formula (3) carrying no additional substituents; (8) cyanuric chloride is condensed first with 4-amino - 41 - hydroxybenzene - 11 - azo - 1 - naphthalene-31-carboxylic-7-sulphonic acid and then with a dyestuff of formula (3) wherein Y bears a sulphonic acid group in the 3-position.