1,5-Dithiacyclooctane (DTCO) is an organosulfur compound with the formula (CH2CH2)CH2S)2.

This cyclic dithioether is a colorless oil that is soluble in polar solvents.

It forms a variety of transition metal thioether complexes.

DTO can be oxidized to the bicyclic dication.

[1] DTCO was first prepared in 4% yield by dialkylation of 1,3-propanedithiol with 1,3-dibromopropane.