Heat resistant cast stainless steels used as tooling for titanium sheet superplastic forming (SPF) are oxidised in near service thermal conditions. Those materials mainly develop chromium and mixed chromium manganese oxide scales which are partially adherent to the metal substrate and show significant spallation depending on the exposure time and thermal cycling. The oxidation and spallation kinetics of an austenitic and a ferritic materials are monitored using thermogravimetry. Acoustic emission technique is used to detect critical temperatures corresponding to spallation and geometric parameters of the spall residues are determined using image analysis of scanning electron micrographs. Thermoelastic and strain energy models are employed to address the preferential mode of spallation of the oxides depending on the exposure time and the conditions of thermal cycling. An attempt is made to estimate the fracture energy of the oxide / metal interface using microstructural consideration such as the interface degradation during the oxidation process.