It is a white crystalline powder, which as a commercial product contains some water (~11.7% wt as the HOBt monohydrate crystal).

It is mainly used to suppress the racemization of single-enantiomer chiral molecules and to improve the efficiency of peptide synthesis.

[3] Due to reclassification as UN0508, a class 1.3C explosive, hydroxybenzotriazole and its monohydrate crystal are no longer allowed to be transported by sea or air as per 49CFR (USDOT hazardous materials regulations).

However, UNECE draft proposal ECE/TRANS/WP.15/AC.1/HAR/2009/1 has been circulated to UN delegates and, if implemented, would amend current regulations thus allowing for the monohydrate crystal to be shipped under the less-stringent code of UN3474 as a class 4.1 desensitized explosive.

[4] The sensitization potential of HOBt was shown to be low (non-sensitizing at 1% in LLNA testing according to OECD 429[5]).