The graphic interface (GUI) from the WESST-OT Simulator was validated using quantitative and qualitative human computer interaction (HCI) methods. In order to achieve this, surveys were applied. Also, GUI design principles were analyzed in the context of WESST-OT. Finally, the goals, objects, methods and rule selection quantitative model (GOMS) was applied. The information acquired was used to enhance WESST-OT’s GUI and at the end was validated following the same methodology. Results show that a better GUI was developed.