The detection of ketene (H₂CCO) in Sgr B2 was reported in 1977 by Turner. Observations of several rotational lines were made using the NRAO 36 Foot Telescope at Kitt Peak. The facility was closed in 2000. Ketene was subsequently found in the cold dust cloud TMC-1 by Matthews & Sears, with further confirmation by Irvine et al.

Ketene is a cousin to aldehydes like formaldehyde, but does not possess the full -CHO group. It is one of the numerous carbon-chain molecules that have been observed in the interstellar medium. Ketene is toxic and unstable, but it is employed industrially for acetylation.