H-D-Ser-OBzl.HCl is the hydrochloride salt of the benzyl ester of D-serine. In peptide synthesis, the benzyl (OBzl) group serves as a protective group for the α-carboxylic acid, enabling selective coupling via the free N-terminal amino group. This makes it ideal as a C-terminal building block or for solution-phase fragment condensations. The HCl salt enhances its stability and solubility, improving handling in organic synthesis. It is commonly used in custom peptide production for research, particularly in pharmaceutical development and biochemical studies requiring D-serine residues. Its role supports precise and efficient peptide chain assembly.