| IMO Class. | Description |
| Class 1 | Explosives |
| 1.1 | Substances and articles which have a mass explosion hazard. |
| 1.2 | Substances and articles which have a projection hazard but not a mass explosion hazard. |
| 1.3 | Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mas explosion hazard. |
| 1.4 | Substances and articles which present no significant hazard. |
| 1.5 | Very insensitive substances which have a mass explosion hazard. |
| 1.6 | Extremely insensitive articles which do not have a mass explosion hazard. |
| Class 2 | Gases: Compressed,Liquefied or Dissolved under Pressure |
| 2.1 | Flammable gases |
| 2.2 | Non-Flammable gases |
| 2.3 | Toxic gases |
| Class 3 | Flammable Liquids |
| 3.1 | Low flash-point group of liquids (flash-point below -18°C.) |
| 3.2 | Intermediate flash-point group of liquids (flash-point of -18°C. up to but not incl. +23°C.) |
| 3.3 | High flash-point group of Liquids (flash-point of +23°C. up to and incl.+61°C.) |
| Class 4 | Flammable Solids or Substances |
| 4.1 | Flammabel solids |
| 4.2 | Substances liable to spontaneous combution |
| 4.3 | Substances which, in contact with water, emit flammable gases. |
| Class 5 | Oxidizing Substances (agents) and Organic Peroxides |
| 5.1 | Oxidizing substances (agents) by yielding oxygen increase the risk and intensity of fire. |
| 5.2 | Organic peroxides - most will burn rapidly and are sensetive to impact or friction. |
| Class 6 | Toxic and infectious Substances |
| 6.1 | Toxic substances |
| 6.2 | Infectious substances |
| Class 7 | Radioactive Substances |
| Class 8 | Corrosives |
| Class 9 | Miscellaneous dangerous substances and articles |
| MHB | Materials hazardous only in bulk |
