By a chemical vapor deposition method with regulating temperature of reactor under ambient pressure conditions (temperature regulated-chemical vapor deposition, TR-CVD), we were able to decorate the internal structure of a mesoporous Al₂O₃ bead (particle size of ~ 1 mm, Sasol) with iron oxide nanoparticles (with a mean lateral size of ~ 1 nm). The iron oxide-decorated Al₂O₃ showed a high catalytic activity for CO oxidation even at room temperature. Subtle deactivation of the CO oxidation activity was observed with increasing reaction time at ~ 100 ^oC. Additionally, the catalyst maintained the catalytic activity even after severe thermal treatment at ~ 900 ^oC, under ambient conditions. We show that our catalysts prepared by TR-CVD have potential for application as oxidation catalysts in industrial process due to the simplicity of their fabrication process as well as the high and stable catalytic performance.