2-([(Benzyloxy)carbonyl]amino)-2-hydroxyacetic acid, also known as Z-Hydroxyglycine-OH or Cbz-hydroxyglycine, is a protected derivative of the non-proteinogenic amino acid hydroxyglycine. It features a benzyloxycarbonyl (Cbz or Z) group protecting the amine functionality and a free carboxylic acid group. This structure makes it a valuable chiral building block. This compound is primarily used in peptide synthesis and medicinal chemistry research as a specialized amino acid synthon. The presence of the α-hydroxy group adjacent to the amino acid backbone introduces unique conformational and hydrogen-bonding properties into peptide chains, which can be exploited to modulate peptide stability, bioavailability, and biological activity. It serves as a key intermediate for constructing peptides containing hydroxyglycine residues or for studying structure-activity relationships. As a Cbz-protected amino acid, it is a stable solid suitable for standard peptide coupling reactions. It falls under the category of non-natural or modified amino acids, which are crucial tools in the development of peptide-based therapeutics, enzyme inhibitors, and biochemical probes.