Organic peroxides pose a hazard because of their ability to chemically oxidise matter, including living tissue. Strong oxidisers can greatly enhance the flammability of other material. Organic peroxides are substances which may be considered derivatives of hydrogen peroxide. Organic peroxides are thermally unstable and may emit heat and give off harmful or flammable gases or vapours whilst undergoing exothermic, self-accelerating decomposition. The rate of decomposition increases with temperature and varies with the organic peroxide formulation. Additionally, they may be liable to explosive decomposition, burn rapidly, be sensitive to impact or friction, react dangerously with other substances, or cause damage to eyes.

All Division 5.2 substances are assigned to UN Packing Group II. 

The substances of Class 5.2 are subdivided as follows: 

  • P1 Organic peroxides, not requiring temperature control; 

  • P2 Organic peroxides, requiring temperature control.


Division 5.2 organic peroxides when packaged for transport are assigned to an alphabetical classification system whereupon type A is the highest risk and is forbidden for transport, and type G poses the least risk and is exempt from the requirements of the ADG Code. Organic peroxides of types B-F must be transported in accordance with NSW Dangerous Goods Road & Rail Transport regulations.

Some organic peroxides are required to be desensitised by organic liquids or solids, inorganic solids, or water. Others are required to be subjected to temperature control during transport. 


Commonly Transported Division 5.2 materials:

  1. Acetyl acetone peroxide

  2. Benzoyl peroxide (bleaching agent)

  3. Butyl peroxydicarbonate

  4. Dibenzoyl peroxide

  5. Organic Peroxide, liquid

  6. Organic Peroxide, solid

  7. Peracetic acid

  8. Peroxyacetic acid

  9. Peroxybenzoic acid