Photinus luciferin is a 1,3-thiazolemonocarboxylic acid consisting of 3,5-dihydrothiophene-4-carboxylic acid having a 6-hydroxybenzothiazol-2-yl group at the 2-position. It has a role as a luciferin. It is a member of benzothiazoles, a 1,3-thiazolemonocarboxylic acid and an imidothioate. It is a conjugate acid of a Photinus luciferin(1-). It is an enantiomer of an ent-Photinus luciferin.