Space exploration represents one of the most difficult and inspiring challenges in the history of human progress. In the pursuit of this goal, the spacecraft propulsion system is one of the key components. High-power Hall thrusters, in particular, represent the right compromise between thrust-to-weight ratio and specific impulse, making them suitable for deep-space missions. The aim of the following thesis work is to analyse the operation of Hall thrusters and to perform a thermal analysis of the 20 kW class thruster produced by SITAEL: the HT20k. Thermal analysis was performed using the student version of the ANSYS Workbench software. An axisymmetric 2D model and a 3D model were created to compare the results of the two analyses.