A novel solution growth of metal oxide nanocrystals within an organized surfactant matrix was developed into mesoporous three-dimensional nanostructured frameworks with tunable mesoporosity. Mesoporous crystalline transition metal oxides, including CeO2 and TiO2, were synthesized. The new mesoporous crystalline TiO2 or CeO2-supported gold nanoparticles showed high reactivity and on-stream stability towards low-temperature CO oxidation even after treatment at 400°-500°C. The gold nanoparticles were directly deposited onto the mesoporous crystalline TiO2 or CeO2 via deposition-precipitation methods and then subjected to heat treatment of different temperatures. The 400°C-aged Au/mesoporous metal oxide catalyst remained very active, achieving 50% conversion around -45°C, which was comparable to T50 values of as-synthesized sample. Gold supported on standard TiO2 P25 and commercial CeO2 prepared under the same condition and calcined at 500°C had a much higher T50 value. Stability tests showed that high temperature-aged Au/mesoporous TiO2 or CeO2 catalyst could maintain its activity at 28°C over an extended period of time. This is an abstract of a paper presented at the 2007 AIChE Annual Meeting (Salt Lake City, UT 11/4-9/2007).