NiO thin films were prepared by electrode position technique onto fluorine-doped tin oxide-coated glass substrates (FTO glass). For these films, a comparative study for the influence of various cleaning processes, deposited voltages, and molar concentrations on adhesion, homogeneity, electrochromic properties, and optical properties were studied. Adhesion and homogeneity properties were studied using intermediate magnification microscope (100x and 400x). Electrochromic (coloration efficiency, reversibility, switching time and stability) properties was investigated using chronoamperometry, cyclic voltametry and transparency during chronoamperometry. Transparency spectrum in the range between 200 nm and 1000 nm, was also used to investigate some optical parameters ( transparency, film thickness and optical energy band gap). Best adhesion and homogeneous properties were observed, for films prepared using dish washing liquid soap followed by successive immersion of substrates into sonicated isopropanol, aceton and ethanol. These films were soacked in diluted HCL, before finally rinsed with deionized water and dried at 100 ᵒC. Highest electrochromic and optical properties was obtained for films prepared on pre-cleaned FTO/Glass substrate, prepared at -700 mV and molar concentration of 0.8 M.