High-energy ball milling is a promising and effective technique for the production of aluminium nanoparticles. Elemental aluminium powder of 325 mesh, 99.5% purity is taken for this investigation. A planetary ball mill, PM 100, with tungsten carbide balls of diameter 9.5 mm was used. The vial containing 62 g of powder and 620 g of tungsten carbide balls in the ratio 1:10 (wt/wt) was utilized. Toluene was used as a wet grinding media in order to reduce the heat produced during ball milling operation. Ball milling was carried out for 70 hours and the obtained nano-particles were characterized using wide angle X-Ray diffraction technique. The peaks were analyzed by using PANalytic X'pert HighScore software. Optimum milling time for producing nanoparticles of size 20-21 nm was found to be 50-60 hours. © 2018 IAEME Publication.