In this research, YSZ-Alumina top coat was deposited on the Hastelloy substrate with a NiCrAlY bond coat by Atmospheric plasma spraying process. YSZ-10 wt-% Al 2 O 3 composite coatings with pyrolysed and un-pyrolysed Al 2 O 3 powder were deposited. High temperature oxidation and thermal shock resistance of both coatings were investigated. Thermal shock test results showed that the lifetime of the YSZ-10 wt-% Al 2 O 3 coating was increased by the pyrolysation of the un-pyrolysed Al 2 O 3 . The network of micro-segmented cracks produced by the pyrolysation of the un-pyrolysed Al 2 O 3 improved the strain accommodation, introducing it as the main enhancement mechanism for TBC life extension. Using of pyrolysed alumina, resulted increased in the flattening degree of the splats, and so reduction of porosity and intra-splat cracks. This, in turn, reduced the permeability of the top coat and decreased the rate of oxide growth on the bond coat.