[‚hī‚dräk′sil·ə‚mēn ‚hī·drə′klȯr‚īd] (organic chemistry) (NH2OH)Cl A crystalline substance with a melting point of 151°C; soluble in glycerol and propylene glycol; used as a reducing agent in photography and in synthetic and analytic chemistry, as an antioxidant in fatty acids and soaps, and as a reagent for enzyme reactivation.