The title compound, C11H12O, has been prepared as a side product in the attempted room-temperature synthesis of (E)-1-phenylpent-2-en-1-one. The molecular structure consists of an approximately planar indanone core (r.m.s. deviation = 0.042 Å) with the ethyl group protruding from this plane. In the crystal, centrosymmetrically related molecules are linked into dimers by pairs of C—H...O hydrogen bonds, forming rings of R22(10) graph-set motif. The dimers are further connected by C—H...π interactions into chains running parallel to [-101].
