This paper describes the design process of the Actuation System for the HEXAFLY-Int hypersonic glider, composed by two control surfaces, hereafter named elevons. In the first part, the high-level architecture of the Actuation System is presented. Then, the requirements generation process is briefly laid out; attention is paid to the procedure used to obtain a reference trajectory compliant with both the mission requirements and the maximum hinge moment not to exceed, coming from the experimental tests. The second part deals with the mechanical design of the Actuation System of each control surface, which is mainly composed of a servo-actuator, a titanium actuation lane, a CMC torsion bar – elevon assembly. A particular attention is dedicated to the innovative design of the torsion bar in terms of CMC manufacturing and mechanical interface with the actuation lane to increase the maximum hinge moment and to minimize its torsional thermo-mechanical deformation for an easier control of the vehicle. This paper concludes with the results of the preliminary ground tests of the torsion bar – elevon assembly.