Oxidation kinetics of platinum modified aluminide and overlay coatings on nickel base superalloys were investigated. Isothermal oxidation tests were carried out at 1050degreesC in synthetic air. Cyclic oxidation tests were performed with 2 cycle frequencies Short term cycles : 1h dwells at 1050degreesC in synthetic air x 1800 cycles Long term cycles : 300h dwells at 1050degreesC in laboratory air x 6 cycles (experiment planned to totalize at least 10 000 hours at high temperature) The mass gain curves point out a large effect of the cycle frequency at 1050degreesC for overlay NiCoCrAlYTa coating whereas the effect is less significant for Pt-modified nickel aluminide coating. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy was used to evaluate the effect of cycle frequency on microstructural evolution. A simple statistical spalling model [1,2], assuming that the parabolic rate constant k(p) and the spalling probability p are constant, is tentatively applied and discussed in view of the microstructural evolution complexity.