In this paper, design and physical configuration of various components of a 10N Monopropellant Hydrazine Thruster focusing on design calculations and optimization of catalytic combustion chamber. According to this design, a prototype of the thruster will be manufactured. The mentioned thruster has been designed as a three-piece modular thruster, including an injection system, catalytic combustion chamber and nozzle. Based on analyzes done for each module, the propulsion characteristics of monopropellant thruster system have been identified and used for the next module as necessary inputs. The combustion chamber dimensions are selected based on criterion of maximum decomposition of 40% ammonia and Mach number of 0.02. Also, the third module is the nozzle, designed as a simple cone. The exterior body design of these three modules and their connections to each other, based on considerations of sizing and weight limitation, as well as being dual purpose for use in the cold and hot tests, has been performed.