A novel reverse microemulsion method was used to prepare SnO2/MgO and SnO2/CaO catalysts. It was found that both the catalysts were active for the reaction of catalytic oxidation of dimethyl ether (DME) in the temperature range of 275 to 300 ℃. SnO2/CaO catalyst exhibits much higher activity than SnO2/MgO. On SnO2/CaO catalyst, DME conversion of 21.8% was obtained at 300 ℃, while selectivities to methyl formate (MF) and dimethoxyethane (DMET) of 19.1% and 59.0% respectively were obtained at 275 ℃.