Edited by E. R. T. Tiekink, University of Malaya, MalaysiaIn the structure of the title compound, C 12 H 12 O 3 , the dihydropyran ring is fused with the benzene ring. The dihydropyran ring is in a half-chair conformation, with the ring O and methylene C atoms positioned 1.367 (3) and 1.504 (4) Å , respectively, on either side of the mean plane formed by the other four atoms. The methoxy group is coplanar with the benzene ring to which it is connected [C bCb-O m -C m torsion angle = À0.2 (4) ; b = benzene and m = methoxy], and similarly the aldehyde is coplanar with respect to the double bond of the dihydropyran ring [C dh -C dh -C a -O a = À178.1 (3); dh = dihydropyran and a = aldehyde]. In the crystal, molecules are linked by weak methyl-methoxy C-HÁ Á ÁO hydrogen bonds into supramolecular chains along the a-axis direction.