Cobalt catalysts are tested in methane decomposition reaction at 475-600 degrees C and pressure similar to 1 bar to evaluate their catalytic properties in non-oxidative methane conversion via an accumulation of carbon. Catalyst preparation method, a nature of a support and temperature regimes are found to strongly influence this process. The best performances are found with the coprecipitated 60-75 wt% Co-alumina catalysts at 500 degrees C. XRD, EXAFS and TEM investigations indicate a close similarity between the Co and Ni catalysts previously studied. However, in contrast to nickel, the carbon filaments with a hollow-like core morphology are produced on the Co catalysts. Data further point that an accumulation of the filamentous carbon is a promising route to utilize methane as a main component of the natural gas.