Yellow–green fluorescent crystals of the title compound, C19H18O3, were obtained by the reaction of hydroxyacetophenone and 4-tert-butylbenzaldehyde with hydrogen peroxide as oxidant. The plane of the benzene ring is slightly twisted to the mean plane of the 4H-chromene-4-one moiety (r.m.s. deviation = 0.0191 Å) by 10.53 (8)°. In the crystal, molecules are linked by pairs of O—H...O hydrogen bonds, forming inversion dimers with an R22(10) ring motif. The dimers are linked via C—H...π interactions, forming sheets parallel to (10-1).