Boroxine () is a 6-membered heterocyclic compound composed of alternating oxygen and singly-hydrogenated boron atoms. Boroxine derivatives (boronic anhydrides) such as trimethylboroxine and triphenylboroxine also make up a broader class of compounds called boroxines. These compounds are solids that are usually in equilibrium with their respective boronic acids at room temperature. Beside being used in theoretical studies, boroxine is primarily used in the production of optics.