In this study, the temperature evolution during stereolithography (SL) processing of a commercial epoxy resin is experimentally measured and numerically simulated. Experimental tests were performed in a SL equipment to evaluate the temperature increase during laser-activated photopolymerization. Temperatures on the resin surface were measured with a thermal video system in both static and moving laser experiments. For the moving laser experiments, the effect of the energy dose was tested by using different velocities of the scanning laser. The experimental results were compared with numerical model prediction obtained by numerical solution of heat transfer equations coupled with an original mathematical model developed for cationic photopolymerization kinetics. The results obtained from numerical simulation were in good agreement with experimental data for the scan performed at the lower energy dose. The process model describes both the temperature increase and the evolution of chemical reaction, providing information about the penetration depth and the cured linewidth.