O-Phospho-D-Serine is primarily used in biochemical research as a substrate or reference compound in studies involving enzymes like phosphatases and kinases, which play critical roles in cellular signaling pathways. It is also employed in the investigation of metabolic processes, particularly those related to amino acid phosphorylation and dephosphorylation. Additionally, this compound finds application in the development of assays to measure enzyme activity or to understand the mechanisms of phosphorylation-related diseases. Its role in studying protein interactions and modifications makes it valuable in proteomics and molecular biology research.