New conductive materials involving Cu+ ions are proposed for electrochromic devices. They are liquid ammoniates which can be used from room temperature up to 80°C, and whose conductivity and p(NH3) can be modulated according to requirements. The synthesis does not require strong acids or complexing agents such as halide ions. The principle of operation of the electrochromic material is the reduction of Cu+ to Cu at the transparent cathode while Cu+ is oxidized to Cu2+ (thus developing a blue color) at the transparent anode. The bleaching is realized by the reverse reactions.