High-temperature Solid Oxide Fuel Cells have a flexible fuel supply and high energy performance. When fed with biofuels, such as biogas, they provide an attractive, ecofriendly and efficient energy system. The Internal Reforming that uses the high temperature of the same fuel cell makes them suitable to biogas, whose carbon dioxide content can be exploited. The fuel cell is characterized by an Internal CO2 Dry Reforming that converts the CH4 in the biogas into an H-2 rich stream, owing to the role of CO2, acting as reforming promoter. The paper presents the formalization and the implementation in Matlab of a steady state-zero dimensional numerical model which describes the various processes of a global self-sustained Indirect Internal CO2 Reforming Solid Oxide Fuel Cell System fed by biogas. In addition to the energy core of the system with reforming and electrochemical section, the plant scheme considers the preheating of fresh gases, partial recirculation of the fuel cell exhausted gases and combustion of the expelled ones. The model aims at assessing energy performance and at monitoring carbon deposition. (C) 2017 Elsevier Ltd. All rights reserved.