A NiOx film with varying crystallinity across film thickness has been prepared by reactive radio frequency magnetron sputtering. The main research achievement is that the electrochemical cycling stability of the NiOx film has been radically improved as compared with NiOx films deposited by the conventional technologies. At the same time, the optical modulation has been also improved, whereas other electrochromic parameters, such as the switching rate and high coloration efficiency have been preserved at the required level. (C) 2018 Elsevier B.V. All rights reserved.