The haloform reaction is a chemical reaction where a haloform (CHX₃, where X is a halogen) is produced by the exhaustive halogenation of a methyl ketone (a molecule containing the R–CO–CH₃ group) in the presence of a base. R may be alkyl or aryl. The reaction can be used to produce chloroform (CHCl₃), bromoform (CHBr₃), or iodoform (CHI₃).