The study of a low power arcjet propulsion system and its application to north-south .station keeping of geostationary telecommunication satellites was carried out at Centrospazio in the framework of the arcjet propulsion system development program conducted by BPD Difesa e Spazio under the Italian Space Agency sponsorship. In order to carry out this study, models were developed for all of the main components of the spacecraft. These included: arcjet thruster, propellant storage and feeding systems, power conditioning, solar arrays and batteries. The relevant characteristic parameters and variables, as well as their mutual-relationships, were defined in order to characterize each of the above components in terms of its performance, mass, electrical consumption and heat flux. The modules describing the different spacecraft systems were integrated in a code capable to simulate the system performance in a given mission and to optimize its design parameters on the basis of a properly chosen criterion.