| Experimental works | Eg (eV) |
| Optical absorption edge on single crystal BeO at 300 K | 10.33 |
| Normal-incidence reflectance of wurtzite BeO at room temperature (estimated band gap value) | 10.63 ± 0.101 |
| Far-ultraviolet reflectance at room temperature | 10.285 and 10.302 |
| Electron energy loss measurements for amorphous and polycrystalline BeO thin films | 9.65 |