The interface between the bond layer and ceramic layer as well as between the bond layer and the substrate in a duplex coating system consisting of a NiCrAl bond coat layer and an Al2O3 + 13 wt.% TiO2 ceramic coat layer has been investigated by scanning electron microscopy and transmission electron microscopy. The lamellar bond layer mainly consists of lamellae aligning approximately parallel to the substrate surface, in which the individual lamellae consist of a thin outer amorphous and nanocrystalline film, an intermediate layer of fine columnar and equiaxed grains and an inner microcrystalline region of big columnar grains. The morphology of the interfacial regions of the above two interfaces is shown to be similar and consists of a thickness of 0.7 mum, or far less, of a mixture of amorphous and nanocrystalline phases. However, besides a certain percentage of area of perfect contact, a small amount of area of non-contact has also been detected among the lamellae or at the interfaces.