The power supply of advanced hand exoprostheses is a critical aspect for ensuring continuous operation, safe energy delivery, and effective management of transient power demands. In this context, Hybrid Energy Storage Systems (HESS) represent a promising solution, as they combine a main energy source with an auxiliary storage element able to support short-duration current peaks generated by the actuation system. This thesis was carried out within a broader research activity focused on the development of the external power system for a hand exoprosthesis. Starting from a previous prototype developed by the research team, the work contributed to the prototyping and optimization of the hardware platform through the validation of selected power modules, the review and functional verification of the implemented circuit sections, and support to component selection.