Résumé : It has been demonstrated that cobalt oxide prepared by oxalate decomposition in oxygen adsorbsboth carbon dioxide and methane.Even if our main concern is related to the development of catalytic sensors, the activation of bothmethane and carbon dioxide at room temperature is of interest for a number of heterogeneouscatalysis systems.In our case, the development of a deposition technique providing high surface area CO3O4depositon the sensor has been successful.