Electrochromic Ni-oxide-based films were prepared by cathodic electrodeposition and, for comparison, also by reactive sputtering. The films were characterized by cyclic voltammetry, spectrophotometry, and infrared absorption spectroscopy. Explorative magnetic measurements, performed at low temperatures using SQUID technology, exhibited a well-defined Curie–Weiss behavior with a transition temperature that was depressed by proton extraction. ©1997 American Institute of Physics.