S-Benzylisothiourea hydrochloride is widely used in organic synthesis as a reagent for the preparation of thiols and sulfides. It serves as a key intermediate in the production of various pharmaceuticals, particularly in the synthesis of compounds with potential antimicrobial and antiviral properties. The chemical is also employed in the development of peptide mimetics and enzyme inhibitors, where its thiourea moiety plays a critical role in binding interactions. Additionally, it finds application in the modification of biomolecules and polymers, enhancing their functional properties for use in drug delivery systems and material science. Its ability to act as a protecting group for thiols further extends its utility in complex synthetic pathways.