Supercritical CO2 power cycles have gained growing interested in the last years, thanks to the particular properties of the carbon dioxide when kept above its critical point, i.e., intermediate between the ones of fluids and those of gases. Thanks to that, sCO2 Brayton loops lead to relevant improvements with respect to the well-known Rankine steam cycles, both in terms of efficiency and size. Their possible applications are multiple, such as concentrated solar power, nuclear secondary circuits, waste-to-energy, and high temperature fuel cells; the interest of this thesis is more centred on the first application. The present work, developed in collaboration with Universitat Politècnica de Catalunya (Barcelona, Spain), focuses on the dynamic modelling of a regenerative sCO2 Brayton cycle using the Modelica language, well known in the field of modelling of complex physical systems, involving, for instance, mechanical, electronics, hydraulic and thermal aspects, with controls.