The present invention provides a process for the production of an aromatic dicarboxylic acid comprising the catalytic oxidation of a hydrocarbon precursor in an organic solvent, comprising the steps of: (i) separating a vent gas from an oxidation stage into an organic solvent-rich liquid stream and a water-rich vapour stream in a distillation stage; and (ii) separating an aqueous purification mother liquor comprising organic compounds from purified aromatic dicarboxylic acid crystals in a separation stage, characterised in that the process further comprises the steps of: (iii) transferring the aqueous purification mother liquor from the separation stage to an extraction stage; (iv) extracting said organic compounds from the aqueous purification mother liquor by contacting the aqueous purification mother liquor at a temperature of at least 90 DEG C with an organic liquid in the extraction stage to form an aqueous phase and an organic phase, wherein the concentration of said organic compounds in the aqueous phase is lower than the concentration of said organic compounds in the aqueous purification mother liquor; and (v) transferring the aqueous phase to said distillation stage. The present invention further provides an apparatus for carrying out the process.