Triphenyl phosphite, with the chemical formula (C6H5O)3P, is a chemical compound that appears as a clear, colorless to pale yellow liquid. It is an organophosphorus compound and is often used as a versatile reagent in various chemical reactions and industrial processes. Triphenyl phosphite is known for its role as a reducing agent, stabilizer, and antioxidant in the production of polymers and plastics. It plays a crucial role in improving the thermal and oxidative stability of these materials, making it a valuable additive in the plastics and polymer industries.

In addition to its use in polymer production, triphenyl phosphite finds applications in the synthesis of various organic compounds and as a key component in the manufacture of antioxidants and flame retardants. It is known for its ability to scavenge free radicals and prevent the degradation of polymers during processing and use. This makes it an important ingredient in the production of high-quality plastics, rubber, and other polymer-based materials.