Phosphorus-containing epoxy systems were prepared from isobutylbis(hydroxypropyl)phosphine oxide (IHPO) and diglycidyl ether of bisphenol A (DGEBA). Diethyl-N,N-bis(2-hydroxyethyl) aminomethyl phosphonate (Fyrol 6) could not be incorporated into the epoxy backbone by a reaction with either epichlorohydrin or DGEBA because intramolecular cyclization took place. The curing behavior of the IHPO-DGEBA prepolymer with two primary amines was studied, and materials with moderate glass-transition temperatures were obtained. V-0 materials were obtained when the resins were tested for ignition resistance with the UL-94 test. (c) 2005 Wiley Periodicals, Inc.