The Ni-W alloy coatings with tungsten content from 32.5 to 61.2 wt.% were prepared in this study by electrodeposition. Experimental results show that the grain size of Ni-W coatings evaluated by XRD decreased with increasing tungsten content in coatings, however, the micro-hardness increased with increasing tungsten content. As-deposited Ni-61.2 wt.%W coating has amorphous-like structure and the grain size is around 1.5 nm, after annealing at 500 degrees C, the hardness of the coating is promoted to 1293 Hv owing to formation of Ni(4)W and NW precipitates. In addition, the heat-treated Ni-W coatings show a better wear resistance than the as-plated Ni-W coatings. (C) 2010 Elsevier B.V. All rights reserved.