We investigated the effect of top metals on the bipolar resistive switching of Metal/amorphous TiO2/Al devices to understand the role of interface chemical reaction between top metal electrode and titanium oxide layer. The Al device of the highest oxygen affinity showed superior memory performance to other devices, which can be attributed to fast formation of interfacial layer (Al-Ti-O), as confirmed by high resolution transmission electron microscopy and electron dispersive spectroscopy. We concluded that diffusion kinetics of the oxygen ions between top metal electrode and amorphous TiO2 layer determine the device performance of Metal/amorphous TiO2/Al as well as thermodynamics (Heat of formation). (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3622295] All rights reserved.