In the present study, Ni-30 vol pct Al2O3 in-situ nanocomposite was developed by reactive milling of NiO-Al-Ni powder mixture followed by spark plasma sintering (SPS). During milling, fcc to hcp transformation was observed in Ni(Al) phase and it transformed back to fcc phase around 773 K (500 °C). The hardness and yield strength of Ni-30 vol pct Al2O3 nanocomposite are approximately two times higher than that of pure Ni of similar grain size. The improved mechanical properties of nanocomposite are attributed to the presence of alumina particles of nanometer size. © 2011 The Minerals, Metals & Materials Society and ASM International.