The growth dynamics and the thermal stability of a Ni nanocrystalline nanowire (NNW) model system fabricated using electrochemical deposition has been investigated using X-ray diffraction, scanning and transition electron microcopy, and differential scanning calorimetry (DSC). It has been found that the thermal stability of the Ni-NNW is dominated by the microstructure movement and the grain boundary rotation mechanism at temperature ranging from 400 to 600 degrees C. The Ni-NNW experiences the Rayleigh instability at temperature approaching the melting point. The observed fragment separation in the Rayleigh phase-transition is much greater than that expected theoretically. (C) 2011 Elsevier B.V. All rights reserved.