The decomposition behaviour of CuO is studied at high temperature and high pressure. Experimental pressure and temperature determine the result. In the region of higher temperature and pressure (≥5.5 GPa, ≥1400 °C), the product is just copper. In the region of lower temperature and pressure (< 5.0 GPa, < 1100 °C), CuO does not decompose. Between the two regions, the product is a mixture of Cu and Cu2O or a mixture of Cu2O and CuO.
