Ionic liquids [ILs] are solvents of interest for applications such as electroplating, winning, and refining of metals. In this study, the conductivity of the AlCl3-trihexyl(tetradecyl) phosphonium chloride ([P-14,P-6,P-6,P-6]Cl) system was characterized over a wide range of AlCl3 concentration and temperature. Cyclic voltammetry was used to determine the electrochemical window of the neat IL using a Pt substrate. The anodic and cathodic potentiodynamic polarization behavior of Al was measured in AlCl3-[P-14,P-6,P-6,P-6]Cl at an AlCl3 concentration of 0.67 mol fraction (X-AlCl3). Aluminum was electrodeposited at a constant potential over a range of potentials (0.3-0.75V); the deposit morphology, current efficiency, and power consumption are provided. The presence and effects of impurities such as H2O and HCl in the ionic liquid are also addressed. (c) 2007 The Electrochemical Society.