Formaldehyde (H₂CO) was one of the first astromolecules to be detected with radioastronomy, by Snyder et al. in 1969. The C(13) substituted variant was reported later in the same year. Singly- and doubly-deuterated H₂CO were reported in 1979 and 1990, respectively. Enrichment of deuterium and other rare isotopes is well-known for both interstellar species and carbonaceous chondrites, such as the Murchison meterorite. Formaldehyde was found in comets in the early 90s.

Formaldehyde is a cousin of a number of other observed astromolecules, including methyl formate (one H replaced with a methoxy group), acetone (both Hs replaced with methyl groups), formamide (one H replaced with an amide group), formic acid (one H replaced with a hydroxyl group), the HCO formyl radical (one H removed), thioformaldehyde (O is replaced with S), and methyleneimine (O replaced with NH).

Commonly known for its role as a preservative with a distinctive odor and should be avoided for safety reasons. However, formaldehyde may have contributed to the origin of life on Earth as a precursor to sugars and other chemical processes.