Layered Li CoO and Li NiO thin films (x | 1) were prepared by a peroxo wet chemistry route x 2 x 2 from Li(I), Co(II) and Ni(II) acetate precursors and the addition of H O . Structural changes during the 2 2 processing of xerogel to final oxide were followed by X-ray diffraction and infrared spectroscopy. Electrochromic properties were determined with in-situ potentiodynamic, potentiostatic and galvanostatic spectroelectrochemical measurements. Single dipped films with composition Li Co O or Li Ni O 0.99 1.01 2 0.94 1.06 2 exhibited stable voltammetric response in 1 M LiClO / propylene carbonate electrolyte after about 60 cycles. 4 22 The total charge exchanged in a reversible charging / discharging cycle was about 630 mC cm for 22 Li Co O and 620 mC cm for Li Ni O oxide films. Galvanostatic measurements showed that 0.99 1.01 2 0.94 1.06 2 1 about 1 / 2 (x | 0.5) and 2 / 3 (x | 0.3) of Li ions could be reversibly removed from the structure of Li Co O and Li Ni O films, respectively. Practical applicability of Li Co O and 0.99 1.01 2 0.94 1.06 2 0.99 1.01 2 1 1 Li Ni O oxide films was studied in electrochromic devices with WO i(H )Li ormolyteiLi Co O 0.94 1.06 2 3 0.99 1.01 2 1 1 and WO i(H )Li ormolyteiLi Ni O configuration. The monochromatic transmittance T (l 5 633 nm) 3 0.94 1.06 2 s of dark blue coloured devices was extremely low (T | 3%), whereas in bleached state the value reached s around T | 70%.