Uniform nickel oxide film is grown on a conducting glass substrate with an aqueous solution of saturated NiF2 center dot 4H(2)O and H3BO3. The quality of NiO is improved after thermal annealing at 300 degrees C in air from the decrease in oxygen vacancy and better F ion passivation on the defects and the dangling bonds. The transmittance of as-deposited NiO/indium tin oxide (ITO)/glass with a thickness of 100 nm is about 78% and is improved to 88% after annealing at a wavelength of 550 nm. By the electrochromic cycling test done 50 times on the annealed NiO film, the transparency ratio is kept at 48% between the fully colored state and the fully bleached state at it wavelength of 550 nm. By the memory time test, the annealed liquid phase deposition-NiO film has a shorter memory time. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3187911] All rights reserved.