This thesis deals with study and thermal analysis of electric motors for high-performance applications, where focus is placed on electric traction motors for e-mobility and railway applications. Calculations are done in COMSOL, a simulation software for Fluid Dynamic Computational calculation. The thesis can be divided in five main topics. In the first chapter, focus is on different cooling layouts for electric motor, operating conditions of traction motor and finally different thermal modelling methods. At the chapter 2, numerical modelling of cooling flow is presented. First an introduction is given on different Computational Fluid Dynamic (CFD) methods including finite element and finite volume.