EDC.HCl (CAS 25952-53-8) is a water-soluble carbodiimide reagent commonly employed in peptide synthesis and other bioconjugation reactions. It facilitates amide bond formation by activating carboxyl groups, enabling their coupling with primary amines in aqueous media. The coupling mechanism involves initial activation of the carboxylic acid by EDC.HCl, generating an unstable intermediate that reacts readily with amines to produce amide linkages, and ultimately EDC is converted into a urea byproduct. Besides peptide synthesis, the reagent is also utilized for nucleotide synthesis, esterification, and lactonization reactions. EDC.HCl can be quantitatively monitored via spectrophotometric methods. Currently, no in vivo or clinical data are reported.