In this work, synthesis of NiAl-Al2O3 nanocomposite powders via the mechanosynthesis route and by using Ni, NiO and Al is investigated. Ignition of the reaction inside the ball-mill vial happens after 110 min; NiO is totally finished and NiAl and Al2O3 as product phases are formed. After 10 h of ball milling, raw materials are totally used in the reaction and only product phases exist in the vial. By continuing the ball milling process to 60 h, better mixing of the synthesized phases and decrement in their crystallite sizes plus partide size are observed. Crystallite sizes of the product phases are in the nanometer range in all ball milling times. Crystallite sizes of NiAl and Al2O3 after 10 h are around 11 nm and 19 nm respectively, and these are reduced to around 8 nm for both phases after 60 h of ball milling. (C) 2018 Elsevier B.V. All rights reserved.