The oxidative dehydrogenation of ethane over NiO-loaded MgO with high surface area was carried out using a fixed-bed flow reactor at 600 degrees C under atmospheric pressure. At 600 degrees C, the oxidative dehydrogenation of ethane (C2H6/O-2 = 1) without dilution with an inert gas resulted in C2H6 conversion of 68.8% and a high C2H4 selectivity of 52.8%, which corresponds to a C2H4 yield of 36.3%. In addition, the catalytic activity did not decrease for at least 10 h. X-ray photoelectron spectra of the catalysts after the reaction exhibited that the initial valence state of Ni2+ (NiO) was maintained during the oxidative dehydrogenation of ethane. However, when NiO-Ioaded MgO was reduced with H-2 prior to the reaction, C2H4 selectivity decreased to nearly zero and high CO and H-2 selectivities were observed with the C2H6 conversion of 50 %, indicating that partial oxidation of C2H6 proceeded. Therefore, it seems important to keep Ni species as an oxide phase on the support, and for this purpose, use of the high surface area of MgO is essential. (c) 2006 Elsevier B.V All rights reserved.