A novel phosphorus-containing vegetable oil (PETR) was prepared through phospha-Michael addition of a diphenyl phosphine oxide to the enone derivative of high-oleic sunflower oil (ETR). The reaction was investigated using the enone derivative of methyl oleate under conventional thermal heating and microwave irradiation. The kinetic study showed a great enhancement of reaction rate for the microwave-initiated addition. The crosslinking of ETR with diaminodiphenylmethane (DDM) via aza-Michael addition was also investigated under microwave irradiation, showing a noticeable acceleration of the curing. The new phosphorus-containing triglyceride was crosslinked with DDM to obtain phosphorus-containing vegetable oil-based thermosets of different phosphorus contents. Limiting oxygen index values from 26.4 to 35.0 for the final materials were obtained, demonstrating that the flame retardant properties of vegetable oil-based thermosets can be improved by adding covalently bonded phosphorus to the polymer. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012