Dioazo dyestuffs are manufactured by diazotizing a primary arylamine of the benzene or naphthalene series, optionally carrying one or more alkyl, substituted alkyl, alkoxy, halogen, nitro, sulphonic acid, acylamino, aroylamino, carboxy, b -hydroxyalkoxy, carboxymethoxy, carboxylic amide or sulphonamido substituents, coupling with a primary arylamine of the benzene or naphthalene series, capable of coupling in the p-position to the amino group and optionally carrying alkyl, alkoxy, hydroxyalkyl, acylamino, halogen or sulpho substituents, diazotizing the resulting aminoazo compound or a sulphonated derivative thereof, and coupling with 2-(31-amino-41-methoxybenzoyl) -amino-5-naphthol-7-sulphonic acid. The products should preferably contain at least two solubilizing groups such as sulphonic acid usually in the form of the alkali metal salt) or carboxy. Cellulosic materials, e.g. cotton or regenerated cellulose, are dyed with the disazo dyestuffs, which are then diazotized on the fibre and developed with an azoic coupling component, e.g. b -naphthol. Examples describe the manufacture of dyestuffs and the production therewith on cotton of dyeings diazotized and developed with b -naphthol, using the diazo compounds from the following aminoazo compounds: (1) and (2) aminoazotoluene sodium sulphonate (obtained by adding sodium nitrite to a mixture of o-toluidine and hydrochloric acid, sulphonating the resulting aminoazotoluene with oleum and salting out the sodium salt of the sulphonic acid from the diluted sulphonation mixture); (3) and (4) sulphanilic acid --> p-xylidine; (5) and (6) the disodium salt of 4-aminoazobenzene-3 : 41-disulphonic acid (obtained by sulphonating aminoazobenzene monosulphonic acid); (7) to (12) 3-aminotoluene-6-sulphonic acid, 4-chloroaniline-5-sulphonic acid, 4-aminobenzoic acid, aniline-2 : 5-disulphonic acid or 2-naphthylamine-6-sulphonic or -6 : 8-disulphonic acid --> aniline; (13) sulphanilic acid --> o-toluidine; (14) to (21) 4-, 3- or 2-aminobenzene-sulphonic acid, 4-chloroaniline-5-sulphonic acid, 3-methyl-4-chloroaniline-6-sulphonic acid, 2-aminotoluene-5-sulphonic acid, or 2-naphthylamine-6 : 8-disulphonic or -6-sulphonic acid --> m-toluidine; (22) and (23) sulphanilic acid --> 6-chloro-2-aminotoluene or m-anisidine; (24) aniline --> 3-aminosuccinanilide; (25) and (26) 1-naphthylamine-4-sulphonic acid or 2-amino-4-acetylaminobenzenesulphonic acid --> m-toluidine; (27) and (28) 3-amino-4-methoxybenzoic acid --> m- or o-toluidine; (29) and (30) sulphanilic acid --> mixed xylidines or acetyl-m-toluylenediamine; (31) to (34) metanilic acid, 4-aminobenzoic acid, 2 : 4 - dimethylaniline - 6 - sulphonic acid or 3 - aminosuccinanilide --> p-xylidine; (35) sulphanilic acid --> 2-methyl-5-methylolaniline; (36) to (42) 2-aminotoluene-5-sulphonic acid, 4-chloroaniline-5-sulphonic acid, 2-amino-4-acetylaminobenzenesulphonic acid, 2-naphthylamine-6-sulphonic or -6 : 8-disulphonic acid, 3 - amino - 4 - methoxybenzoic acid or 4-nitro - aniline-6-sulphonic acid --> p-xylidine; (43) sulphanilic acid --> 2 - methyl - 5 - isopropyl aniline; (44) metanilic acid --> o-anisidine; (45) and (46) 4-chloroaniline-3-sulphonic acid or 2-aminoanisole-4-sulphonic acid --> 3-amino-4-methoxybenzyl alcohol; (47) to (62) 4- or 3-aminobenzenesulphonic acid, 2 : 4-dimethylaniline-6-sulphonic acid, 2- or 4-amino-benzoic acid, 3-amino-6-hydroxybenzoic acid, 3-amino-4-methoxybenzoic acid, aniline-2 : 5-disulphonic acid, 2-aminotoluene-5-sulphonic acid, 4-chloroaniline-5-sulphonic acid, 3-methyl-4-chloroaniline-6-sulphonic acid, 2-amino-4-acetylaminobenzenesulphonic acid, 3 - amino - succinanilide or 2-naphthylamine-6-sulphonic or -6 : 8- or -4 : 8-disulphonic acid --> cresidine; (63) and (64) 2-naphthylamine-4 : 8- or -6 : 8-disulphonic acid --> 2 : 5-dimethoxyaniline; (65) 1-naphthylamine-3 : 8-disulphonic acid --> a -naphthylamine; (66) to (70) sulphanilic acid, aniline, p-phenetidine, 4-aminoacetanilide or 4-aminobenzanilide --> 1-naphthylamine-6-sulphonic acid; (71) 1-amino-2-methoxynaphthalene-6-sulphonic acid --> a -naphthylamine; (72) to (74) 3- or 4-amino-benzenesulphonic acid or 4-aminotoluene-5-sulphonic acid --> aniline. Additional components specified are: first components: cresidine, 5-nitro-2-aminoanisole, p-aminobenzamide, p-aminobenzenesulphonamide, p-aminobenzyl alcohol, b -(p-aminophenoxy)-ethanol, p-aminophenoxyacetic acid, 2-amino-5-sulphobenzoic acid, 4-chloro-5-amino-2-acetylaminoanisole, m-aminobenzotrifluoride and 5-chloro-2-aminobenzoic acid; middle component: formyl-m-phenylenediamine. 2-(31-Amino-41-methoxybenzoyl) -amino-5-naphthol-7-sulphonic acid is obtainable by treating 3-nitroanisic acid with thionyl chloride, condensing the resulting 3-nitroanisoyl chloride with J-acids and reducing the nitro group. Specifications 4768/09, 259,970, [both in Class 2 (iii) 390,529 and 469,562 are referred to.