Experiments of oxidative dehydrogenation of ethane in the presence of a Pt/gamma -Al2O3 catalyst were performed at high temperatures and short contact rimes under isothermal and adiabatic conditions. High ethene yields were observed. The comparison of the catalytic data with the results of gas-phase experiments and with the predictions of a detailed kinetic model of homogeneous oxidative pyrolysis of hydrocarbons suggested that radical reactions had a fundamental role in the synthesis of olefins, while the catalyst phase mostly behaved as heat supplier through combustion routes. (C) 2001 Elsevier Science B.V. All rights reserved.