As a concept of the storage of electrical energy from renewable sources, the concept power-to-gas (PtG) is being considered for the energy turnaround. In this process the electrical energy is converted into the gaseous fuels hydrogen or methane. The structure of a power-to-gas plant is divided into the electrolysis and the methanation. The master thesis contends the development of a simulation model for a methanation as a part of a power-to-gas concept. The simulation model was developed in a design and an offdesign case. The design case calculates the reactor dimensions and the output stream for a specific input stream with a defined fraction, temperature and pressure. The second case, the offdesign, uses the design reactor and calculates the output after a defined amount of operating hours. If necessary it changed input fraction, temperature or pressure. For the implementation of the calculation the simulation model was separated into components, these were used from the Design case as well as the offdesign case. The components are the gibbs model, kinetic model, heat loss and degradation model. For the interconnection between the components is a step model in use. Last part is the successfully validation of the simulation model and illustration of selected simulation results. For the simulation comparing different pressures, inlet temperatures, compositions and catalyst age were performed.