Abstract: The invention relates to a process for the preparation of 1:2 chromium, 1:2 cobalt, 1:2 nickel or 1:2 iron complex azo dyes diazotisation, coupling and metallizing, without isolation of the coupling product, which process comprises diazotizing at least one amine of the benzene or naphthalene series in aqueous solution and coupling the diazonium compound so obtained to at least one coupling component of the benzene or naphthalene series or of the heterocyclic series, such that the azo dye obtained as intermediate contains groups suitable for metal complex formation, and carrying out the diazotization or coupling in the presence of a chromium, cobalt, nickel or iron donor.The dyes obtained by the process of the invention are suitable for dyeing in particular wool or synthetic textile polyamide fibre materials as well as leather, and for use as wood mordant dyes.