This thesis deals with the work on ESA-uProp program sponsored by the European Space Agency (ESA) that aims at developing a CubeSat Test Platform (CTP) for the verification and qualification of miniaturized electric propulsion systems. The goal of the project is to assess the mutual interactions between the current CubeSat technologies and the new propulsion systems, in order to improve the Technological Readiness Level (TRL). The thesis is focused on the first phase of design of ESA-uProp 3 project: the heritage of the previous project ESA-uProp 2, the analysis of the objectives and the drivers that define the product, the preliminary design, development tests and the beginning of integration of the prototype.