Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the European Space Agency, into the development of hydrogen peroxide monopropellant thrusters using advanced catalytic beds. The present paper focuses on the design of two different demonstration thrusters with nominal ratings of 5 N and 25 N. Design requirements and specifications are presented, followed by the main results of a concept study, which was conducted to define the approximate dimensions needed. Some details about the specific design of the two prototypes and the choice of the main components are provided, with particular regard to the sensors and transducers to be used during the experimentation. Different catalytic bed configurations, including pure silver gauzes and pellets coated with manganese oxide or platinum, are going to be tested in the prototype thrusters, in order to find the optimum one for further industrial development. A dedicated test bench, designed and realized by Alta S.p.A. for tests on the thruster prototypes, is also illustrated.