PURPOSE: To obtain the title compound which is used to produce biphenyltetracarboxylic dianhydride readily in high yield with industrial advantage by effecting oxidative coupling of o-phthalic diester in the presence of a specific catalyst.

CONSTITUTION: Using a catalyst containing a palladium chelate salt, which is formed by allowing a palladium salt obtained by treating Pd with an acid together with a support such as silica, activated carbon or alumina, to react with a basic divalent ligand such as 1,10-phenanthroline, oxidative coupling reaction of o-phthalic acid diester is carried out in the absence of a solvent, at 50W300°C under normal to 300 atmospheric pressure, as a gas containing molecular oxygen is bubbled to give the subject compound. The coexistence of the support in the reaction mixture facilitates the efficient separation and recovery of Pd as a catalyst component, and regeneration to the catalyst and they are circulated in the course of the reaction, recovery, regeneration.