(3-Hydroxypropyl)phosphonic acid diethyl ester is primarily utilized as an intermediate in the synthesis of various organic compounds, particularly in the production of flame retardants. Its phosphonic ester group makes it valuable in modifying materials to enhance their fire-resistant properties. Additionally, it is employed in the development of corrosion inhibitors, where it helps protect metal surfaces by forming a protective layer. In the field of agriculture, it serves as a precursor for certain agrochemicals, contributing to the formulation of pesticides or herbicides. Its versatility also extends to the pharmaceutical industry, where it is used in the synthesis of active pharmaceutical ingredients (APIs) with specific therapeutic properties.