In the present work, the 2024 aluminum alloy (Al-2024) alloy has been produced by mechanical alloying (MA). The alloy was then strengthened by dispersion of carbon nanotubes (CNTs) during different times. Thus, the effect of CNTs concentration and milling time on the microstructure of the Al-2024-CNTs composites was studied. The results show a homogeneous dispersion of CNTs into the Al-matrix phase by mechanical milling (MM). It was observed that the increment in the milling time, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MA. The finest particle size was obtained at 20 h of milling. These observations were confirmed by scanning and transmission electron microscopy. After 10 h of milling, Cu, Mg and other alloying elements constituting the Al-2024 alloy, form a solid solution and only some remnant Mn particles were observed but not detected by X-ray diffraction. (C) 2011 Elsevier B.V. All rights reserved.