Unsupported Fe, Co and Ni catalysts are active in the oxidative dehydrogenation of ethane (ODHE) at low temperature. A conversion of 1% is achieved at 585, 438 and 487 K, respectively. The selectivity towards ethylene is found to be ca. 60% at low conversion. As the reaction temperature increases, the selectivity remains nearly constant for Ni whilst it decreases for Fe and Co. This behaviour has been explained by comparing the catalytic properties of Co and Ni towards ethane and ethylene oxidation. The ODHE intrinsic activity sequence (Co>N>Fe) is similar to that observed for the homomolecular exchange of oxygen, confirming that these catalysts are in an oxidized state in the course of the ODHE reaction. The study of the reduction and oxidation of unsupported and silica-supported nickel catalysts using magnetic methods has shown that the catalytic activity is not related to the ease of the Ni2+-Ni-0 transition. TAP experiments carried out over Ni have revealed that the oxygen species involved in the reaction are irreversibly held by the catalyst at 573 K (possibly O-) from which a reaction mechanism is proposed. Furthermore, this series of experiments have shown that ethane is irreversibly adsorbed and that CO2 originates from a parallel-consecutive scheme.