1H-Benzotriazol-5-ol, commonly known as HOBt, is a specialty chemical primarily used as a coupling additive in peptide synthesis and amide bond formation. It is employed with carbodiimides (such as DCC or EDC) to enhance reaction efficiency, suppress racemization, and minimize side reactions during the production of peptides, proteins, and pharmaceuticals.

HOBt is essential in solid-phase peptide synthesis (SPPS) and solution-phase synthesis for research, drug development, and biotechnology applications. Its triazole moiety facilitates the activation of carboxylic acids into active esters.

Additionally, due to its structural similarity to benzotriazole, HOBt exhibits mild corrosion inhibition properties for copper and its alloys in certain aqueous environments, though this is not its primary application. It may also find use as a chelating agent in metal surface treatments and as an intermediate in organic synthesis.