Modified novolac resins with benzoxazine rings were prepared. The synthetic method involved the preparation of 1,3,5-triphenylhexahydro-1,3,5-triazine as an intermediate that further reacts with the novolac resin. The catalytic effects of phenols, carboxylic acids, and Lewis acids on the benzoxazine ring-opening polymerization were shown. The curing behavior of the benzoxazine compounds and the thermal properties of the cured resin were studied, and the results indicated improved degradation behavior for flammability. V-0 materials were obtained when the materials were tested for ignition resistance using the UL-94 test. (C) 2003 Wiley Periodicals, Inc.