Nanocrystalline Ni produced by pulsed electro deposition (PED) was investigated by perturbed gamma gamma -angular correlation spectroscopy (PAC) using radioactive In-111. The stabilisation of the Ni grains by oxygen against growth during thermal treatment was investigated using different electrode materials or a modified FED process. In Ni samples not intentionally doped with oxygen, the conversion from nano- to polycrystalline Ni was observed to occur up to 1070 K.