Monofunctional and difunctional benzoxazines with ortho-norbornene functionality have been synthesized via Mannich condensation. The structure of synthesized monomers has been confirmed by H-1 nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The ortho-norbornene functional benzoxazine resins show excellent features both in the synthesis of benzoxazine monomers and the properties of the corresponding thermosets. The benzoxazines containing norbornene groups can polymerize with multiple polymerization mechanisms rather than the single mechanism common to traditional 1,3-benzoxazine resins. The polymerization mechanisms are monitored by in situ FT-IR and differential scanning calorimetry (DSC). Activation energy of polymerization is also studied by DSC. Moreover, the thermoset derived from the difunctional benzoxazine monomer exhibits high thermal stability with the glass transition temperature of 365 degrees C and a high T-d5 of 463 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.