Uniform mesoporous rhodium oxide/alumina hybrid have been prepared following a facile one-pot self-assembly approach using P123 as template. Such hybrid nanomaterials display a high dispersion of both the noble metal oxide and the alumina within mesoporous structure in a broad Rh/Al mole ratio up to 8 : 1, which makes them attractive materials for catalytic applications. After coating on MEMS micro-heater, a catalytic combustion type methane gas micro-sensor was fabricated and investigated for its sensing performance. The mesostructure-based sensor demonstrated a short T90 response time, relatively high signal output, high enough signal/noise ratio and extraordinarily low power consumption.