PURPOSE: To obtain the subject compound in high yield and selectivity, keeping excellent catalytic activity, without lowering the yield of phenolic compounds, by reacting an aromatic hydrocarbon with a carboxylic acid and molecular oxygen in the presence of a specific palladium-based catalyst.

CONSTITUTION: The objective compound is produced by reacting a carboxylic acid with an aromatic hydrocarbon (preferably benzene or naphthalene) and molecular oxygen in vapor phase or a mixture of vapor and liquid at 100-350°C in the presence of a catalyst produced by supporting a catalyst component containing a palladium component and one or more lanthanide components selected from a gadolinium component, an ytterbium component and a ruthenium component on a carrier. Preferably, the amount of the lanthanide component is 0.1-5,000mol per 100mol of the palladium component and that of the palladium component supported on the carrier is 0.001-10wt.%.