A supergravity field offers several advantages during electrodeposition. Electrodeposition assisted by a supergravity field was employed to produce nickel-cobalt (Ni-Co) alloy coatings. The grain size, surface morphology, preferred crystal orientation, microhardness and wear resistance of the deposited Ni-Co coatings were studied systematically, and all were found to be dependent on the Co concentration in the plating bath and current density. Under a supergravity field, the surface morphology was found to be smoother than that obtained in a normal gravity field. Grain sizes of the as-prepared Ni-Co coatings were refined, and an average grain size of 15 nm was obtained. A Co content of 40.56 wt% was obtained using a low Co concentration in the bath. Ni-Co alloy coatings with a maximum microhardness of 660 HV were prepared, and the hardness value was significantly higher than that for coatings prepared by conventional electrodeposition. A minimum friction coefficient of 0.14 and a very low wear weight loss of 2.5 mg were achieved in our experiments.