Different colouration states of W03 and NiO H have been analyzed by optical spectroscopy and characterized with The films were produced by reactive evaporation. Electrochromic (EC) behaviour were investigated in liquid electrolyte experiments and as a part of allsolid -state devices. Changes in optical properties were determined as a function of injected charge. Spectral colouration efficiencies (CE) are presented for both materials. A linear relationship between macroscropic optical behaviour and change in oxidation state is proved for W03 up to a certain amount of injected charge.