A fuel cell is an electrochemical device that converts so direct and continuous chemical energy of a fuel into electricity. Because of this direct conversion, we can achieve high returns by failing to follow a thermodynamic cycle as happens to the engines of internal conversion would be limited by the income tax by the Carnot cycle. In the case that concerns us here, fuel cells and solid oxide cells can be fed with large numbers of fuel, largely due to the high temperatures of the stack to allow the reformed fuels such as methane at the anode. These high temperatures involve a number of advantages as can be the greatest tolerance to impurities in the fuel or the possibility of integration with a thermal machine to exploit its residual heat. Its main disadvantages are corrosion and problems resulting from the thermal expansion of materials. Through the development of a model of behavior of the system to cover the operating range of the stack, is aimed to provide a theoretical analysis and have a tool that serves to the simulation of other energy systems based on solid oxide cells. It uses Matlab®, because of its flexibility and ability to integrate different numerical models. With a mathematical model of the stack thermoelectric proceed to the calculation, calculating curves tension-current density and power-power density, the electrical performance of the stack, as well as the energy obtained by the system