For dyeing or printing textile and other dyeable materials by forming azo dyes in situ, use is made of neutral or alkaline compositions containing (a) a diazotized aromatic aminestabilized against reaction with a coupling component in a neutral or alkaline medium, and (b) a coupling component containing an azo group. Component (a) is stabilized by conversion into a diazoimino compound or a nitrosamine or an azosulphonate. The compositions may be produced in the form of powders, pastes or solutions, and after they have been applied to the material to be dyed, the colour is developed by treatment with an acid. The following examples are given: (1) the diazoimino compound from diazotized 4-chloro-2-aminoanisole and piperidine-a -carboxylic acid is mixed with the azo compound from diazotized m-nitraniline and 1-amino-7-naphthol, and the mixture is pasted with the aid of caustic soda solution, monopol oil, and starch-tragacanth thickener; cotton goods are printed with the paste and then treated with steam containing acetic and formic acid vapours, brown prints being obtained; (2) the diazoimino compound from diazotized 4-chloro-2-aminoanisole and methylglucamine is mixed with the azo compound from diazotized 4-chloro-2-aminoanisole and 1-amino-7-naphthol, and the mixture is pasted and applied as in example 1, brown prints being obtained; (3) a printing paste is prepared containing the nitrosamine from 4-chloro-2-aminoanisole, the azo compound from diazotized 4 - chloro - 2 - aminoanisole and 1 - amino - 7-naphthol, leucanol, aqueous caustic soda, and starch-tragacanth thickener; cotton goods are printed with the paste, and the colour is then developed by treating the goods either with steam containing acetic acid vapour or with a bath containing acetic acid and sodium chromate, brown prints being obtained; (4) a printing paste is prepared containing the diazoimino compound from diazotized 4-chloro-2-aminoanisole and piperidine-a -carboxylic acid, benzene-azo-resorcinol, aqueous caustic soda, monopol oil, and starch-tragacanth thickener, and the paste is applied as in example 1, brown prints being obtained; (5) as in example 4, except that benzene-azo-2 : 5-dioxynaphthalene is used in place of benzene-azo-resorcinol, brown prints being again obtained. A table is given also of compositions containing ingredients selected from the following lists: (a) arylamines from which diazoimino compounds are prepared: 4 - chloro - 2 - aminotoluene, aniline, 4-chloro-2-aminoanisole, and dianisidine; (b) stabilizers used in making the diazoimino compounds: piperidine - a - carboxylic acid, sarcosine, and methylglucamine; (c) coupling components: the azo compounds from 1-amino-7-naphthol and the diazo compounds of 4-chloro-2-aminoanisole, 5-nitro-2-aminoanisole, 2 : 5-dichloraniline, aniline, 3-chloraniline, 4-nitraniline, 4 - chloro - 2 - nitraniline, 2 : 5 - dichloro - 4-nitraniline, 2 : 4-dimethyl-6-nitraniline; 2 : 5-diethoxy - 4 - nitraniline, m - aminobenzotrifluoride, 4-chloro-2-aminotoluene, 4-nitro-2-aminotoluene, 3-nitro-4-aminotoluene, 4-nitro-2-aminoanisole, 3-nitro-4-aminoanisole, a -naphthylamine, b -naphthylamine, and a -aminoanthraquinone; the compositions yield black or brown shades. Other specified diazo compounds to be used in a stabilized form are those from o-chloraniline, 4-chloro-2-aminophenetole, 4 - chloro - 2 : 5 - dimethylaniline, 4-benzoylamino - 2 : 5 - dimethoxyaniline, 1-methoxy-2-naphthylamine, 4-chloro-2-aminodiphenyl ether, o-aminoazotoluene, 4 : 41-diaminodiphenylamine, and 3-aminocarbazole. Other specified reagents for the production of diazoimino compounds are 1 - methylaminoethane-2-sulphonic acid, proline, nipecotinic acid, benzyleneimino-p-sulphonic acid, 1-naphthylamine-2 : 4 : 8-trisulphonic acid, and 2-ethylamino - 4 - sulphobenzoic acid. Other specified coupling components are p-nitrobenzene - azo - phloroglucinol, 2 : 5 - dichlorobenzene-azo-2 : 7-dioxynaphthalene, p-methylbenzene - azo - 1 : 5 - dioxynaphthalene, 3 - (p-nitrobenzene) - azo - 4 : 41 - dioxydiphenyl, benzene - azo - 1 : 5 - dioxyanthracene, benzeneazo - m - phenylenediamine, benzene - azo - 1 : 5-diaminonaphthalene, p-chlorobenzene - azo - m-aminophenol, benzene - azo - 3 : 5 - dihydroxyaniline, 2 : 5 - dichlorobenzene - azo - 2 - amino - 7 - naphthol, 2 : 5-dichlorobenzene-azo-1-amino-5-naphthol, 2 - nitro - 4 - methylbenzene - azo - 2 - amino-6-naphthol, a -naphthalene-azo-1-amino-6-naphthol, benzene-azo-1 : 3-diamino-5-naphthol, and p-nitrobenzene - azo - 4 - amino - 1 : 5-dioxynaphthalene. Other specified materials which may be treated are regenerated cellulose, cellulose esters and ethers, wool, silk and leather. Other specified components of the compositions are ethyl alcohol, ethylene glycol monoethyl ether, and ethanolamine. Reference is made also to the production of pigments by acidifying the compositions in aqueous solution or suspension.