In this study, we investigate the O K-edge spectra of Yb 2 Si 2 O 7 and Yb 2 SiO 5 , which are one of the most promising candidates for EBCs among rare-earth silicates; Yb 2 Si 2 O 7 and Yb 2 SiO 5 have a phase stability of high temperatures, moderate thermal expansion coefficients, and excellent water vapor corrosion resistance . Spectral simulations are performed based on DFT combined with a core-hole technique. Experimental spectra are obtained via EELS from a polycrystalline sample. For providing a benchmark for the employed calculation methodology, we first present the calculated O K-edge spectra for three polymorphs of Yb 2 O 3 and compare them to literature data.