Hydroxydiazo compounds are obtained by diazotizing and dealkylating alkyl ethers of 2-aminophenols substituted in the 4- and 6-positions by nitro, sulphonic or sulphonamide groups; the sulphonamide groups may be substituted on the nitrogen atom by alkyl, aralkyl or aryl groups, which may be substituted. Dealkylation may be effected by heating after diazotization or by neutralizing the diazo solution with sodium carbonate in the cold; dealkylation may also occur during diazotization. The hydroxydiazo compounds are then coupled with any component capable of coupling in o-position to the auxochrome group; phenols, naphthols, naphthylamines, aminonaphthols, pyrazolones and b -diketones are specified as suitable components. The dyes obtained may be converted into metal compounds, in substance or on the fibre. In examples of the manufacture of dyes: (1) 1-methoxy-2-amino6 - nitrobenzene - 4 - (4<1>-sulphophenyl) sulphonamide is diazotized and then heated to 40 DEG C., whereby the o-hydroxydiazo compound is obtained in the form of its diazo oxide; the solution is treated with 1-phenyl-3-methyl-5-pyrazolone to yield a scarlet dye for wool; the dyeing is changed to orange by after-treatment with bichromate; (2) 1-ethoxy-2-amino-6-nitrobenzene - 4 - (4<1> - sulphonaphthyl - 1) sulphonamide is diazotized at 30 DEG C., whereby a solution of diazo oxide is obtained directly; the solution is treated with b -naphthol to yield a violet-brown dye for animal fibres; the dyeing is changed to violet by after-treatment with copper sulphate; (3) 1 - methoxy - 2 - amino - 6 - nitrobenzene - 4 - (2<1> - methyl - 4<1> - sulphophenyl)sulphonamide is diazotized and dealkylated as in example 2, and the product is coupled with m-toluylenediamine; the product, with the aid of a chromium auxiliary agent, gives brown dyeings on animal fibres; (4) the dye obtained in example 2 is heated with aqueous sodium acetate and chrome alum, and the chromium compound of the dye is p salted out; it dyes leather, wool, weighted or unweighted silk and other animal fibres in black shades; (5) the product of example 1 is heated with aqueous chromium sulphate and sulphuric acid, and then neutralized; the product dyes wool in orange shades; (6) the product of example 3 is heated with aqueous copper sulphate and sodium formate; the coppered dye gives brown shades on animal fibres. The following dyes have also been prepared:--(a) 2-amino-6-nitrophenol - 4 - sulphophenylethylamide --> 1-acetylamino - 8 - naphthol - 3 : 6 - disulphonic acid; this dye yields violet shades on wool, and its chromium and copper compounds yield green-black and violet shades respectively; (b) 2 - amino - 6 - nitrophenol - 4 - sulphomethylamide --> 2 - ethylaminonaphthalene - 6 - sulphonic acid; this dye gives red shades on wool, and its copper compound gives violet shades; (c) 2 - amino - 6 - nitrophenol - 4 - (5<1> : 7<1> - disulphonaphthyl - 2) sulphonamide --> ethylacetoacetate; this dye gives orange shades on wool, and its chromium and copper compounds give yellow-brown and yellow shades respectively; (d) 2 - amino - 6 - nitrophenol - 4 - (2<1> - methyl - 4<1> - sulphophenyl) sulphonamide --> acetoacetic o-chloranilide; this dye gives yellow shades on wool, and its chromium and copper compounds give yellow-orange and orange shades respectively; (e) 2 - amino - 6 - nitrophenol - 4 - (2<1> : 4<1> - dimethyl - 6<1> - sulphophenyl) sulphonamide --> 2 : 4-diaminotoluene; this dye gives brown-red shades on wool, and its chromium and copper compounds give brown shades; the chromium and copper compounds specified have been prepared in substance and on the fibre. In examples of dyeing processes: (7) uncarded wool is dyed with an aqueous solution of the product of example 4 in the presence of sulphuric acid; (8) weighted silk threads are dyed with an aqueous solution of the product of example 5 in the presence of sodium sulphate; (9) chrome leather is dyed with an aqueous solution of the product of example 6 in the presence of acetic acid. The Specification as open to inspection under Sect. 91 states that the starting materials are alkyl ethers of 2-aminophenols substituted in the 4- and 6-positions by electronegative substituents. This subject-matter does not appear in the Specification as accepted.