In this paper, a numerical and experimental study on the compression and transfer molding of rubber materials will be presented. A three dimensional analysis is used for the numerical study. The program developed in this study can predict the flow pattern, temperature, degree of cure and pressure change during filling and post-filling. Of particular interest is the change of pressure and press force during post-filling due to the thermal expansion of a material in conjunction with the cross-linking effect on the viscosity. PVT, viscosity and curing kinetics data of the rubber material were measured for accurate calculation of pressure during molding. Some other experimental data such as filling patterns, press force and cure distribution at the molded sample were also obtained for validation of the simulation results. The comparison shows reasonable agreement between simulation and experiment.