In continuation of a previous study (1) of the dissolution of commercially pure aluminum (99.2% Al) in alkaline solutions, the effect of impurities, concentration of sodium hydroxide, temperature, agitation, and the effect of an external current on the dissolution of a series of aluminum specimens ranging in composition from 99.2 to 99.998 per cent Al was investigated. Increasing quantities of impurities (iron being the most effective) increase the rate of dissolution. The largest increase is at the concentration of iron representing the limit of solubility of iron in solid aluminum. During the dissolution process the impurities in aluminum accumulate on the surface and accelerate the rate of dissolution.