<p>This study investigates the performance of composite thermal barrier coating (TBC) system in comparison with conventional TBC on non-heat-treated stainless steel substrates. Air plasma spray is used to deposit both conventional TBC comprising of 8 wt.% yttria-stabilized zirconia (YSZ) topcoat and NiCoCrAlY bond coat that is compared to composite TBC in which the topcoat consists of inner conventional TBC layer and composite outer layer of 8 wt.% YSZ + Al₂O₃ + TiO₂. Feedstock for the composite topcoat was prepared at laboratory scale through sintering and ball milling. These TBCs are characterized for the phases present, microstructure and elemental distribution and phase stability in as-deposited and thermally cycled conditions. The as-deposited composite and conventional configurations have shown uniform microstructure in the layers without any crack between them. The average nanoindentation hardness of composite topcoat was ≈ 27% higher than the conventional topcoat, due to addition of alumina and titania. The measured weight gain over time as the temperature changed from 25 to 1300&#xa0;°C, for conventional topcoat configuration was nearly 89% higher than composite topcoat configuration, indicating its greater thermal resistance. There is a higher elastic moduli mismatch between conventional topcoat and bond coat (30%) as compared to the composite topcoat and bond coat (13%) that resulted in higher crack density and average length of microcracks in conventional topcoat after thermal cycling. Therefore, this multilayer thermal barrier coating comprising of NiCoCrAlY and 8YSZ and a composite topcoat of 8YSZ + Al₂O₃ + TiO₂ could provide a balance of thermal insulation and mechanical durability for high-temperature applications.</p>