The electrochemistry of binuclear tungsten salt, K3[W2Cl9], was examined in the Lewis acidic 66.7-33.3 mole percent (m/o) aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl3- [EtMeIm]Cl) room-temperature ionic liquid as it pertains to the electrodeposition of the Al-W alloy. We revealed that Al-W alloy without chloride contamination can be electrodeposited from the 66.7 m/o AlCl3-[EtMeIm]Cl with the K3[W2Cl9]. Interestingly Al- W alloy having an amorphous phase as well as W-rich Al alloy over 96 atomic present (a/o) W were successfully produced. However the Al-W alloy became covered with powdery deposits with increasing the W content in the alloy. The resulting Al-W alloy showed a favorable chloride-induced pitting potential comparable to that produced by a usual sputtering method if the W content was less than ca. 3 a/o W. Copyright © 2012 by The Electrochemical Society.