Two different ferritic stainless steels (AISI 409Nb and 434L) with different Cr level were manufactured through powder metallurgical techniques. These sintered steels are typically used for exhaust pipes and turbochargers. Both materials were uniaxially compacted and then vacuum sintered at 1225 and 1275 degreesC respectively. Microstructural features and physical properties (density, porosity) of as sintered materials were examined. Oxidation performance was evaluated through isothermal experiments in air and thermogravimetry techniques. Global weight gains are very similar for both steels in isothermal tests carried out at 700, 800 and 900 degreesC for 240 h. However, oxidation at 1000 degreesC is different for both steels. X-ray diffraction and scanning electron microscopy allow to explain the differences of kinetics in base of composition of scale layers. Finally, thermogravimetry gives information regarding the kinetics of oxidation processes.