The invention relates to a process for the preparation of aromatic hydroxy compounds, starting from the corresponding halogenated aromatic compounds and replacing the halogen atom or atoms by the hydroxyl group. The process comprises converting the halogenated aromatic compound into the hydroxy compound by treatment with concentrated sulfuric acid, with the addition of an aldehyde and at elevated temperature.The aromatic hydroxy compounds are used as intermediates, for example for the manufacture of disperse and vat dyes.