Advanced epoxy resins containing naphthalene and flame retardant moiety [tetrabromobisphenol-A (TBBA) or cyclicphosphineoxidediol] in the backbone were synthesized. T(g)s of epoxy resins containing naphthalene structure are higher than that of the diglycidyl ether of bisphenol-A (DGEBA), and a T-g of 237 degrees C was obtained when the tetrafunctional naphthalene-containing epoxy resin was used. In air, TGA of the phosphorus-containing thermosets displayed 11.5-22.2 wt% char yield at 800 degrees C, while the TBBA-containing network was oxidatively decomposed to nearly zero residue. The efficiency of phosphorus as a flame retardant was found to be much higher than that of bromine. The combination of tetrafunctional naphthalene-containing epoxy resin with cyclic phosphine oxide diol has resulted in high Tg (239 degrees C) and high limited oxygen index (LOI) 35. (C) 2000 Elsevier Science Ltd. All rights reserved.