Both the cryomilled Cu powder and the gas-atomized Cu powder were sprayed onto aluminum substrate using the cold spray process. This study focused on the formation and tribological behavior of the nanocrystalline (NC) Cu coating in comparison to its coarse-grained (CG) Cu counterpart. The results showed that the as-sprayed deposit presented a dense microstructure. The mean grain size of the NC Cu coating was about 30 nm. Investigations on the worn surface of the NC coating revealed that the plastic deformation with grooves and some debris were prominent with no visible cracking. Nanocrystalline Cu coating showed a good wear resistance with a low friction coefficient. The enhancement of the wear properties of the NC Cu was attributed to the grain refinement and the superior hardness. (C) 2012 Elsevier B.V. All rights reserved.