C6H4O3

The molecular formula C6H4O3 may refer to:
 * 2,5-Diformylfuran
 * 2,4-Diformylfuran
 * 3,4-Diformylfuran
 * Monohydroxybenzoquinone
 * 2-Hydroxy-1,4-benzoquinone
 * 3-Hydroxy-1,2-benzoquinone
 * 4-Hydroxy-1,2-benzoquinone
 * 4-Cyclohexene-1,2,3-trione
 * 2,5-Oxepindione
 * 2,7-Oxepindione