A novel benzoxazine containing benzoxazole structures (Boz-BOA) was synthesized and its thermoset [P(Boz-BOA)] was prepared. For comparison, another benzoxazine-based 4,4'-diamine diphenyl methane (Boz-MDA) was also synthesized using a simplified procedure. The structure of Boz-BOA and Boz-MDA was confirmed by Fourier transform infrared (FTIR) and 1H-NMR. Using FTIR and differential scanning calorimetric scans method, the curing behavior of Boz-BOA was probed, and the structure of P(Boz-BOA) was addressed, which was similar to that of P(Boz-MDA). Data of dynamic mechanical analysis showed that P(Boz-BOA) exhibited a better modulus retention at high temperature than P(Boz-MDA), which was attributed to benzoxazole structure restricting the mobility of chains, even at high temperature. P(Boz-BOA) also exhibited high glass transition temperature (Tg), excellent thermal stability, and low coefficient of thermal expansion value at wide temperature range. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012