Transient multiphysics simulations are performed to investigate the thermal and electric performance of a thermoelectric generator (TEG) module placed between hot and cold blocks. Effects of heat radiation, thermal and electric contact on the TEG are examined and the simulated results are compared with experimental data. The predicted temperature difference across the TEG module and the electric voltage and power are in very good agreement with the experimental data. The radiation effect on the thermal and electric performance is negligible and the temperature at the interface of the TEG module substrates is predicted to be non-uniform. The peak temperatures are found in the both ends of the legs, and the maximum Joule heat is generated at the leg ends connected with the hot substrate.