XRD, XRD in situ XPS, electrochemical and AFM studies of an unknown phase formed during electrochemical deposition of Ni-W alloy in a citrate electrolyte were carried out. It has been determined that a thin, highly textured film of nonstoichiometric NiWO4 was formed during codeposition of nickel and tungsten. The amount of the nickel tungstate was higher on the coating electrodeposited in electrolyte containing amine acid-asparagine. The quantity of the nickel tungstate grew in the electrodeposition period of similar to 60 min and subsequently kept constant although the thickness of Ni-W alloy continued to increase. The quantity of the nickel tungstate formed increased with the temperature of electrolyte, however it decreased with the pH and current density. (c) 2006 Elsevier B.V. All rights reserved.