Abstract We report observation of a first order thermal depolarization peak at 190 K in NiO single crystals which we attribute to the reorientation of Ni 3+ Ni V 2+ dipoles. Analysis of the data in terms of these bound polarons, using a non-adiabatic hopping model, yields values of activation energy, E = 0.31eV and the polaron band width, J = 8.6 × 10 −6 eV.