Mechanically induced reactivity of gibbsite in an attrition mill is focused in this paper. Reactivity of milled gibbsite, assessed in terms of its dehydroxylation and dissolution in alkali solution, is found to increase with the increase in milling time. Besides analysing the increased reactivity in terms of the changes in physicochemical characteristics, an attempt has also been made to correlate the reactivity with physicochemical changes. Changes in the physicochemical characteristics of gibbsite during milling in an attrition mill and corresponding change in reactivity are compared with that observed for gibbsite milled in a planetary mill, described in Part 1; thus a comparison of two different types of mills in terms of their efficiency in bringing out structural/reactivity changes is illustrated using the same feed stock, gibbsite. (C) 2014 Elsevier B.V. All rights reserved.