Yes, formaldehyde (HCHO) reacts with hydrogen cyanide (HCN) in a nucleophilic addition reaction to form formaldehyde cyanohydrin, also known as glycolonitrile.

Reaction:

HCHO + HCN → HOCH₂CN

This reaction is an example of cyanohydrin formation. The cyanide ion (CN^-) acts as a nucleophile, attacking the electrophilic carbonyl carbon of formaldehyde. The proton from HCN then protonates the oxygen atom, resulting in the formation of the cyanohydrin.

Source:

• Cyanohydrin Reaction
• Cyanohydrin Reaction