The title compound [systematic name: (E)-2-hy­droxy-5-(phenyl­diazen­yl)cyclo­hepta-2,4,6-trien-1-one], C13H10N2O2, is essentially planar with an r.m.s. deviation of 0.036 (2) Å and a dihedral angle of 1.57 (8)° between the phenyl and tropolone rings. In the crystal, mol­ecules are linked by pairs of O—H⋯O hydrogen bonds into inversion dimers. The dimers are further connected by C—H⋯O hydrogen bonds and π–π stacking inter­actions, with centroid–centroid distances of 3.6934 (9) and 3.6282 (9) Å.