In this study different concentrations of methane in hydrogen have been fed into a microtubular SOFC while determining the cell performance over time. Also the effect of adding water to the gas as a reforming agent has been analyzed with respect to power output and cell stability. In addition to the characterization by measuring the power with time gas chromatography and impedance spectroscopy were used in order to obtain further information about the cell behavior. Post mortem electron microscopy and atomic force microscopy analysis has shown the influences of the blends on the anode microstructure after different test series. Also the influence of the working temperature and of the rate of fuel utilization on the cell performance was investigated. Depending on the working conditions stable cell performance could be achieved but also three different degradation mechanisms could be found.