Acid-base bifucntional oxide catalyzed the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide. It is found that ZrO₂, H₃PO₄/ZrO₂ and CeO₂-ZrO₂ solid solution are effective to the selective synthesis of dimethly carbonate. From the investigation of zirconia, it is suggested that neighboring acid and base sites are the key for DMC synthesis. The addition of H₃PO₄ promoted the DMC formation. This is due to the weak Brønsted acid site which is formed from the interaction between H₃PO₄ and ZrO₂. In addition, it is recently found that the CeO₂-ZrO₂ solid solution is highly active at much lower temperature than ZrO₂ and CeO₂.