The oxidative coupling of methane (OCM) was carried out in a polytropic fixed-bed reactor applying a Zr/La/Sr catalyst developed by the Neste company. Over this catalyst the OCM reaction follows a complex reaction scheme which includes primary parallel reaction steps to CO, CO2 and C2H6 and consecutive reactions of ethane to ethylene or COx. Yield of higher hydrocarbons C2+ Obtained with this catalyst strongly depended on reaction conditions, i.e. low partial pressures of methane and oxygen obtained by diluting the feed gas with nitrogen and high reaction temperatures promoted C2+ selectivity and yield. The maximum yield amounted to 21.4% (20 Vol-% CH4, 9 Vol-% O-2, 71 Vol-% N-2, T = 860 degrees C; X(CH4) = 41.8%, SC2+, = 52.5%). This result belongs To the highest yields reported in the open literature.(1)).