We have developed a metal oxide gas sensor based on a micro-heater structure on a membrane able to work until 550°C, with a power consumption equal to 60mW at this temperature. In this paper, we have presented the electro-thermal simulation of this structure with COMSOL TM , in order to check the temperature distribution on the surface, compare the maximum temperature between simulation and measurement for different power consumption, find the time necessary to obtain a stabilized temperature. The results obtained are: a good distribution of the temperature at the surface of the structure, the simulated and measured temperature curves in function of the power consumption are very close, the time required to stabilize the temperature of the membrane is about 60ms.