Cobalt(II) oxide, also known as cobaltous oxide, is a chemical compound. Its chemical formula is CoO. It contains cobalt in its +2 oxidation state as an ion. It also contains oxide. It can be green or red crystals. It can also be a grey or brown powder.
- CoCl2 + 2 NaOH → 2 NaCl + Co(OH)2
- Co(OH)2 → CoO + H2O