The cathodic dissolution of aluminum and aluminum alloys is a potentially important but poorly understood phenomenon. In this work, the dissolution of pure Al and AA6061 aluminum alloy under cathodic polarizations was investigated. The dissolution rates of the base metal and minor alloying elements were measured in real time using atomic emission spectroelectrochemistry. These data were used to verify the stoichiometry of 4.62 +/- 0.22 hydroxides per dissolved Al ion for pure Al. It was found that at high cathodic currents, the cathodic dissolution of SiO2 was observed while Mg2+ species precipitated on the surface perhaps in the form of MgSiO3. These precipitated solid phases did not alter the OH/Al stoichiometry, The Al-n[Fe-m,Mn1-m]Si phases appear to serve as local cathodes accelerating Al dissolution leading to the formation of "trenches" around the intermetallic particles. (C) 2013 Elsevier Ltd. All rights reserved.