Disclosed is a basic aluminum material having enhanced antiperspirant activity, the material having the empirical formula Al₂(OH) 6-a X a , where 0.5 ≦ a ≦ 5.0, and X is a univalent complex oxoanion of nitrogen, chlorine and other halogens, which forms salts with Al³⁺ in aqueous solution so that these salts are essentially completely dissociated, which is readily soluble in water with metallic ions in the solution, and which forms conjugate acids that are strong acids; and wherein the material is characterized by:

(a) size exclusion high performance liquid chromatography peaks corresponding to peak 3 and peak 4 of size exclusion chromatograms formed by HPLC technique;
(b) a peak 4 relative area of at least 25%, a peak 3 relative area of less than 60%, the sum of the relative peak 3 and peak 4 areas being at least 50%; and
(c) less than 10% chromatographic peaks eluting at shorter retention times than peak 3, corresponding to peaks 1 and 2.

Illustratively, the univalent oxoanion can be ClO₃⁻, ClO₄⁻, IO₄⁻, and preferably NO₃⁻. The material is characterized by having et least 25% by weight thereof in the form of Al b polyhydroxyaquoaluminum species. Also disclosed are antiperspirant compositions including the basic aluminum material, a zirconium, hafnium, titanium and/or tin antiperspirant active material and a neutral amino acid, and methods of forming the basic aluminum material and the antiperspirant composition. The basic aluminum material can be formed at relatively low temperatures, without first forming a dilute solution of a basic aluminum compound, and the basic aluminum material has a stable enhanced activity in aqueous solution over a relatively long period of time.