Diphenylphosphine oxide is widely used as a key intermediate in organic synthesis, particularly in the production of organophosphorus compounds. It serves as a precursor for the synthesis of phosphine ligands, which are essential in catalytic processes, including cross-coupling reactions and hydrogenation. Additionally, it is employed in the development of flame retardants, where its phosphorus content enhances the fire-resistant properties of materials. In polymer chemistry, it acts as a stabilizer and modifier, improving the thermal and mechanical properties of plastics. Furthermore, it finds applications in the pharmaceutical industry for the synthesis of bioactive molecules and drug candidates. Its role in coordination chemistry is also notable, as it forms complexes with metals for use in various catalytic systems.