Efficient conversion of methane to higher hydrocarbons via oxidative coupling of methane "OCM" is one of the dream reactions in heterogeneous catalysis. Promising yields of C-2 hydrocarbons were reported for nanostructured catalysts based on MniNa/W-SiO2. However, the exact role of the nanostructure could not be studied so far due to collapse of the pore structure of the SiO2 support at typical OCM temperatures. We investigate porous SiC as an alternative catalyst support for OCM catalysis. Mn/Na/W/SiC catalysts with different pore size were synthesized via impregnation, calcined under different atmospheres and then studied in OCM. The calcination critically impacts the pore structure and surface area of the obtained catalysts. Calcination in nitrogen preserves the support's structure significantly better than calcination in air. However, the nitrogen-calcined catalysts show a strong loss of porosity during OCM testing. The loss of porosity is caused by the presence of Na, which induces a melting of the surface layer that typically protects SiC against bulk oxidation. OCM tests suggest that the activity and C-2 yield of Mn/Na/W/SiC catalysts depend critically on the supports stability, i.e. the surface area retained under reaction conditions. (C) 2017 Elsevier B.V. All rights reserved.