The present work involves synthesis, characterization and evaluation of hardness and sliding wear resistance of electrodeposited nanocrystalline Ni-W alloys. Crystallite size reduced with an increase in current density due to an increase in the W content. Ni-W alloy with 9.33 at.% W plated at 75 °C exhibited the maximum hardness of 638 HV. Alloys plated at 75 °C followed direct Hall-Petch relation. However, alloys plated at 85 °C exhibited an inverse Hall-Petch relation below a crystallite size of 15 nm. Wear resistance of alloys plated at 75 °C increased due to an increase in hardness with a reduction in the crystallite size up to 20 nm. It reduced due to brittle fracture of the coating below 20 nm. Wear resistance of alloys plated at 85 °C increased with a reduction in the crystallite size in the direct Hall-Petch region and decreased in the inverse Hall-Petch region. Ni-W coatings with 6-8 at.% W exhibited superior wear resistance. © 2005 Elsevier B.V. All rights reserved.