Niobium oxide films are promising cathodic electrochromics that in many aspects can compete with the more frequently studied WO3 films. The films reported herein were prepared using the sol-gel route from a NbCl5 precursor. The electrochromic properties were pronounced for crystalline films that are heat-treated at 500 degrees C and exhibited transmittance changes between coloured and bleached states of 60 % in the UV and 80 % in the VIS-NIR regions. Improved bleaching and more reversible electrochromism of thick niobium oxide films (d > 250 nm) were obtained by lithiation.