Phenoxathiin (dibenzooxathiane) C<sub>12</sub>H<sub>8</sub>OS is a heterocyclic compound of molecular weight 200.25632 g/mol with the CAS Registry Number 262-20-4.
Diphenyl ether is a starting material in the production of phenoxathiin via the Ferrario reaction. Phenoxathiin is used in polyamide and polyimide production.