Nowadays, more and more electrical motors are being used in mobile applications, such as hybrid cars for the automotive sector or even in aeronautics applications. A typical example is the solar impulse airplane which is propelled with four electrical motors powered only with solar cells. This example is for now an exception, but it is very likely it will become more and more common in coming years. The importance of having a light and ecient motor for such applications is obvious. This report presents a way to design optimal electrical motors in terms of minimal mass and maximal eciency. The goal of this project is to test the capability of genetic algorithms to optimize electrical motors.