1-Naphthyl phosphate monosodium salt monohydrate is utilized as a phosphorylating agent in organic synthesis, particularly for preparing phosphate esters in biochemical and pharmaceutical applications. It functions primarily as a chromogenic substrate in phosphatase assays, such as those for alkaline phosphatase, where enzymatic dephosphorylation releases 1-naphthol, enabling colorimetric detection of enzyme activity. The naphthyl group enhances its solubility and stability in aqueous-organic solvent mixtures, supporting homogeneous reaction conditions. It is also applied in enzyme kinetic studies and the development of analytical methods for investigating dephosphorylation in cellular signaling and protein regulation pathways.