Microwave-absorbing catalyst H3PW12O40 center dot xH(2)O/C (HPW/C) was prepared for biodiesel synthesis using cottonseed oil and methanol as feed materials. The hot spot temperatures in the catalyst were calculated by considering the absorbed microwave power, temperature rise, and heat transfer between catalyst and liquid phase. The intrinsic kinetics model for heterogeneous transesterification was established on the basis of the Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism, and the model parameters were decided by using the kinetics experimental data and the calculated results under the hot spot temperatures. Results showed that the hot spot temperatures of the catalyst were far higher than the temperature of bulk liquid, and the simulated kinetics results agreed well with the experimental data.