Coatings with high thermal stability and oxidation resistance are highly anticipated for various high-temperature applications. In this work we compare three different approaches to increase the oxidation resistance of nanocomposite TiAlSiCN coatings with exceptionally high thermal stability: (i) deposition of a thin Al top-layer, (ii) Al ion implantation into their topmost surface, and (iii) deposition of a thin AlOx, top-layer. The coatings were annealed in air at 1000, 1100, and 1200 degrees C for 1 h and their oxidation was studied using scanning electron microscopy and glow discharge optical emission spectroscopy. The obtained results demonstrate that the deposition of a thin top-layer of amorphous AlOx, increases the oxidation resistance of the TiAlSiCN coatings from 1000 to 1100 degrees C. This decreases the gap between the high thermal stability (1300 degrees C) and oxidation resistance of the TiAlSiCN coatings, which is particularly important for high-speed and dry cutting applications. In contrast, the deposition of either a thin Al top-layer or Al ion implantation resulted in a negative effect. The factors affecting the rapid oxidation of such coatings at 1000 and 1100 degrees C are discussed. (C) 2015 Elsevier B.V. All rights reserved.