Dicumyl peroxide is an organic compound with the formula (C6H5CMe2O)2 (Me = CH3).

Classified as a dialkyl peroxide, it is produced on a large scale industrially for use in polymer chemistry.

It serves as an initiator and crosslinking agent in the production of low density polyethylene.

Alternatively, it can be produced by the addition of hydrogen peroxide to α-methylstyrene.

Upon heating, it breaks down by homolysis of the relatively weak O-O bond.