| Oxidation State | Substances |
| Se-II | H2Se |
| Se0-I | Se cations clusters, exp: Se42+, Se82+ |
| SeI | Se2Cl2 , Se2Br2 |
| SeII | ? |
| SeIV | SeO2 , H2SeO3 , SeO32- (aq), |
| SeOF2 , SeOCl4 , SeOBr2 , SeF4 , | |
| SeCl4 , SeBr4 , SeBr62- | |
| SeVI | SeO3 ?, H2SeO4 , SeO42- (aq), |
| SeO2F2 , SeO2Cl2 , SeF6 |
