Spectrally-selective solar absorbers are widely used in solar hot water and concentrating solar power (CSP) systems. However, their performance a high temperatures (>450 °C) is still not satisfactory due to high infrared (IR) emittance and lack of long-term thermal stability. Here, we explore yttria-stabilized-zirconia (YSZ) cermet-based spectrally selective surfaces for high temperature solar absorber applications. The developed multilayer selective surface-comprises two sunlight-absorbing YSZ cermet layers with different metal volume fraction inside the YSZ matrix, two anti-reflection coatings (ARCs), and one tungsten IR reflection layer for reduced IR emittance and improved thermal stability, deposited on a polished stainless steel substrate. The fabricated solar absorbers are tested for their long term thermal stability at 600°C. We found a distinct change in surface morphology of the solar absorbers when oxygen is "highly deficient in the YSZ-ARC layers: The oxygen deficiency can be effectively overcome through increasing the oxygen partial pressure during sputtering, which leads to a stable solar absorber with an