Ni-33.3at%Si elemental powder mixtures were mechanically alloyed by a high-energy ball mill, followed by CIP (cold isostatic pressing) and HIP (hot isostatic pressing) for different processing conditions. Only elemental phases (Ni and Si) were observed for the 15 min mechanically alloyed (MA 15 min) powder. but Ni 2 Si and elemental phases were observed to coexist for the 30 min mechanically alloyed (MA 30 min) powder. Elemental Ni and Ni 2 Si phases were observed for the HIPed compact of MA 15 min powder at 100 and 150 MPa for 2 hr at 800 ? C . Only the Ni 2 Si phase was, however, observed for the HIPed compacts of MA 30 min powder. For the HIPed compacts, the highest sintered density was obtained to be 99.5% of theoretical density by a HIP step at 1100 ? C at 150MPa for 2hr. The hardness values of the HIPed Ni 2 Si compacts at 1100 ? C at 100/150 MPa for 2 hr were higher than HRC 66. The densification and mechanical property of HIPed Ni 2 Si compacts were found to depend on more HIP temperature than HIP pressure.