2-Chlorobenzaldehyde (o-chlorobenzaldehyde) is an organic compound with the formula ClC6H4CHO. It is one of three isomeric monochlorinated benzaldehyde. 3-Chlorobenzaldehyde and 4-chlorobenzaldehyde are the other isomers. Whereas benzaldehyde is prone to autoxidation, the 2-chloro derivatives are more air-stable.