Lithium cobalt nitrides Li3−2x Co x N (0.1≤ x ≤0.44) have been prepared and investigated as negative electrode in the 1/0.02V potential window. The evolution of the unit cell parameters and unit cell volume with the Co content show a solid solution behaviour. Whatever the Co content, all these nitrides are electroactive with a single step around 0.6V/0.7V for the discharge and charge processes, respectively. The electrochemical behaviour observed is typical of a Li intercalation compound and involves the Co2+/Co+ redox couple in the interlayer plane combined with the reversible accommodation of Li+ ions in the cation vacancies located in Li2N− layers. XRD experiments performed after discharge, charge and cycling tests clearly indicate the hexagonal layered structure of the host lattice is maintained. This intercalation process explains the excellent capacity retention found after 50cycles. A specific capacity of 180mAhg−1 at C/20 and 130mAhg−1 at C/5 rate (100mAcm−2) is achieved for Li2.23Co0.39N. ac impedance measurements have allowed to characterize the kinetics of the reaction.