This invention relates to a process for the manufacture of aromatic carboxylic acids by exothermic liquid phase oxidation of an aromatic feedstock. More particularly, this invention relates to the efficient energy recovery of the exotherm produced by the liquid phase oxidation of an aromatic feedstock. An apparatus useful in recovery of energy from the preparation of aromatic carboxylic acids by the exothermic liquid phase reaction of an aromatic feedstock is described where the primary means of energy recovery is by raising moderate pressure steam. This is coupled with a process to recovery low temperature energy using a process commonly known as an organic Rankine cycle and/or a heat pump. The combination of energy recovery methods increases the overall energy recovery and enables the recovery of reaction energy as either thermal energy (steam) or work or a combination of both.