Trimorpholinophosphine oxide is primarily used as a flame retardant in various polymer materials, including plastics and textiles. It works by promoting char formation and reducing the release of flammable gases during combustion, thereby enhancing fire safety. Additionally, it finds application in the synthesis of specialty chemicals, where it acts as a catalyst or intermediate in organic reactions. Its stability and compatibility with different matrices make it suitable for use in coatings, adhesives, and electronic components, where fire resistance is critical.