A utilization of heavy crude oils having a high total acid number (TAN) has been increased recently as a result of its lower price, and deacidification processes by esterification or thermal decarboxylation using heterogeneous catalysts can be a possible way to remove or neutralize acidic components in heavy oils. A conversion of benzoic acid as a model component of naphthenic acids was investigated using metal-modified H-form ferrierite in a batch reactor to verify the separate contributions of Bronsted and/or Lewis acid sites for esterification and decarboxylation reactions with methanol. The surface acid properties of metal-modified ferrierite with K, Zr, and P species significantly altered the extent of decarboxylation and esterification activities by showing a higher removal rate of benzoic acid on K-modified ferrierite. The amount of Lewis acid sites on metal-modified ferrierite was well-correlated with the conversion of benzoic acid. An increased esterification activity on K-modified ferrierite was mainly attributed to enhanced consecutive decarboxylation of methyl benzoate to form toluene selectively, which was formed by esterification of benzoic acid, as well as an enhanced decarboxylation of benzoic acid to benzene on the Bronsted and Lewis acid sites, respectively.