Mn-Na-W silica supported catalysts are highly selective toward ethylene and ethane in the oxidative coupling of methane (OCM) process. However, they present lower activities than La/Sr/Ca catalysts and subsequently a lower ethylene productivity. Optimisation of the Mn-Na-W catalysts has been focused within the range of 2-8 wt% of active elements relative to the support, while silica is partially converted into inert cristobalite. This study focused on the increase of the activity of Mn-Na-W catalysts while maintaining their intrinsically high C-2 selectivity. The increase in the concentration of the active elements with respect to the support revealed that the improvement of the catalyst activity was possible but limited. A high concentration of Mn-Na-W favours the formation of a smooth cristobalite phase and strongly decreased the number of active sites. The silica support was replaced by silica-free supports to limit the formation of cristobalite. The use of SiC as a support led to the formation of cristobalite near the surface of the catalysts but the porous SiC skeleton, which remained non-oxidised at the core of the catalysts, allowed maintaining a high surface area. SiC supported catalysts thus presented higher activities than silica catalysts. The use of alpha-alumina support led to catalysts with lower performances and revealed that exposed alumina was detrimental for the catalyst performance. (C) 2014 Elsevier B.V. All rights reserved.