Carbon monoxide - CO

Carbon monoxide, CO, is a flammable, odourless gas that is highly toxic. It is mainly formed as an intermediate product when organic material, such as fossil fuels, is burned. The gas is released in combustion processes during incomplete combustion.

The gas plays a major role in many chemical reactions used in the chemical industry. When released into the ambient air, it is a temporary pollutant that eventually is oxidised to carbon dioxide.

Carbon monoxide is highly toxic because of its ability to interfere with haemoglobin to prevent the blood from carrying oxygen to the cells. This can cause headaches, weakness and vomiting, and at higher concentrations, loss of consciousness, convulsions and death.

Carbon monoxide poisoning is relatively common and is reported to be the most common type of fatal poisoning in many countries.


  • Molecular weight:

    28.01 g/mol

  • Gaseous phase:

    Gas density (0 °C, 1,013 bar): 1,250 kg/m3
    Gas density (25 °C, 1,013 bar): 1,145 kg/m3

  • Solid phase:

    Melting point (1,013 bar): -205,1 °C

  • Liquid phase:

    Boiling point (1,013 bar): -191,5 °C
    Liquid density at boiling point: 793,2 kg/m3