A memristor device is disclosed comprising: a first electrode; a second electrode; a cathode metal layer disposed on a surface of the first electrode; and an active region disposed between and in electrical contact with the second electrode and the cathode metal layer, the active region comprising at least one layer of an amorphous metal oxide, wherein when a switching voltage is applied between the first and second electrodes, the active region exhibits a resistive switching behaviour. A method of fabricating a memristor device is also disclosed.