If the organic phase contains a large amount of the basic compound or water, acid cleavage of the organic phase gives the desired 2,6-dihydroxynaphthalene in a markedly decreased yield.Preferably, the water-insoluble or sparingly water-soluble organic solvent, especially a ketone, is added in an amount of 0.2 to 10 parts by weight, especially 0.3 to 5 parts by weight, per part by weight of the oxi