A bimodification synthesis method—“in situ oxidation at the interface (IOI) coupled with an ion exchange”—has been developed for the internal surface modification of mesoporous silicon oxide (MPS) templates. First, manganese oxide was formed at the internal surface of the MPS template through IOI. In the IOI method, high-valent oxo-anions of manganese (MnO4−) were used for the selective oxidation of poly(ethylene oxide) (PEO) groups of the Pluronic P123 (PEO20PPO70PEO20; PPO=poly(propylene oxide)) surfactant and they formed manganese oxide at the organic–inorganic (corona) interface. The oxide formation was restricted at the corona interface by a positively charged CTA+ (cetyltrimethylammonium) head group of the cationic surfactant CTABr. Then, the second modification of the MPS template was also performed by introducing promoter cations (Cs+, K+, or H+) through an ion exchange reaction between the cations and CTA+. The bimodified MPSMnX (X=Cs, K, or H) samples preserved the mesoporosity and high surface area of the MPS template. The bimodified MPSMnX samples were found to be more active, selective, and stable than the singly modified MPSMn sample for the gas-phase oxidation of toluene.