Tri(acryloyloxyethyl)phosphate (TAEP) and di(acryloyloxyethyl)ethyl phosphate (DAEEP) were used as reactive-type flame-retardant monomers along with commercial epoxy acrylate and polyurethane acrylate oligomers in ultraviolet (UV)-curable resins. The concentrations of the monomers were varied from 17 to 50 wt %. The addition of the monomers greatly reduced the viscosity of the oligomers and increased the photopolymerization rates of the resins. The flame retardancy and thermal degradation behavior of the UV-cured films were investigated with the limiting oxygen index (LOI) and thermogravimetric analysis. The results showed that the thermal stability at high temperatures greater than 400° C and the LOI values of the UV-cured resins, especially those containing epoxy acrylate, were largely improved by the addition of the monomers. The dynamic mechanical thermal properties of the UV-cured films were also measured. The results showed that the crosslink density increased along with the concentrations of the monomers. However, the glass-transition temperature decreased with an increasing concentration of DAEEP because of the reduction in the rigidity of the cured films, whereas the glass-transition temperature increased with the concentration of TAEP because of the higher crosslink density of the cured films. © 2005 Wiley Periodicals, Inc.