Hybrid systems, such as the Solid Oxide Fuel Cell (SOFC)/Gas Turbine (GT), are a promising technology due to its high efficiency and clean way to produce energy. For a better understanding of SOFC/GT hybrid system, various experiments were conducted and analyzed with the main objective of obtain the response and behavior on the solid oxide fuel cell for future system identification. For this project, a solid oxide fuel cell model coupled with a gas turbine as real hardware developed at the U.S. Department of Energy NETL in Morgantown, West Virginia was used.  First, a characterization of the fuel cell model was conducted for different fuel compositions. Each fuel composition was managed to properly match the fluid and energy demand of the turbomachine   as an integrated hybrid system. A composition was chosen and a test was conducted to analyzed system behavior.  The test consisted in changes of opening on the hot air bypass valve. Finally, the data was analyzed and the results shown a big correlation between solid temperatures and current density on the fuel cell.  Diffusion losses and current density were highly correlated as well, showing almost the same behavior at the beginning and end of the fuel cell.