Oxidative coupling of methane over a La2O3/CaO catalyst was investigated in laboratory-scale fluidized-bed reactors (LD = 5 and 7 cm) in the following range of reaction conditions : T = 700 - 880 degrees C, P-CH4 = 41 - 72 kPa and P-O2 = 6 - 29 kPa. The maximum C-2+ selectivity and yield amounted to 73.8% (T = 800 degrees C; X(CH4) = 13.1%, Y-C2+ = 9.7%) and 16.0% (T = 840 degrees C, X(CH4) = 34.0%, S-C2+ = 47.2%), respectively. Axial gas concentration profiles revealed that C-2+ selectivity was not only influenced by oxidative consecutive reactions, but also by steam reforming of ethylene. When diluting the catalytic bed (m(cat) = 145 g) with quartz (m(SiO2) = 200 and 400 g), a slight decrease of the selectivity (1-2%) was observed. The dilution of the feed gas with nitrogen only led to only a small increase (< 2%) of the C-2+ selectivity.