Thioxanthone is a heterocyclic compound that is a sulfur analog of xanthone.

Thioxanthone can be prepared by the reaction of diphenyl sulfide with phosgene in the presence of catalytic aluminium chloride.

Thioxanthone dissolves in concentrated sulfuric acid to give a yellow colored liquid with intense green fluorescence.

A mixture of the thioxanthone derivatives of 2- and 4-isopropylthioxanthone (ITX) is used in the printing industry.

Pharmaceutical drugs that are derivatives of thioxanthone include hycanthone and lucanthone.