The purpose of this paper is the development of a numerical model to predict DC Hall thruster performance. The model is almost ideal, since secondary losses are usually neglected, but still useful to understand and calculate the main power losses in the thruster, together with the most important performance parameters such as required power, specific impuse, thrust and consumption. In particular, modellization takes into account the difficulties in vacuum testing, so all the efficiencies are calculated starting from easily measurable quantities. Discharge chamber is modelled in 1-D in order to simplify the study of the plasma physics, ionization and acceleration regions, with a focus on the differences between dielectric and metallic walls discharge chamber.