In this paper a reactive organophosphorous substance will be presented as f
lame retardant for epoxy resins. This halogen-free material is harmless reg
arding toxicology and there is no formation of corrosive fire effluents in
case of a fire. As the flame retardant can be reacted with the resin, it is
very suitable for applications requiring good mechanical properties of the
final product. This is shown by a composite and an adhesive application.