Dissolution of mechanically activated Panzhihua ilmenite was carried out at 100 degrees C with a 50% sulfuric acid solution. The particle size, specific surface area, crystallite size, lattice strain and mechano-chemical reaction of milled ilmenite were measured. The cleavage induced by energetic milling occurred more preferentially along the a-axis of ilmenite unit cell. It was found that the defects formed in milling process, especially the lattice strain in the c-axis of ilmenite unit cell, greatly enhanced the leaching reaction. At low temperatures, the leaching reaction is likely to start along the direction of the basal plane (0001) of milled ilmenite. With the mechanically activated ilmenite, leaching conversion at 100 degrees C reached 82.1%. However, the leaching kinetic tests revealed that the ball milling only partially activated the ilmenite. The initial rapid dissolution is due to the leaching of both the fine powders and highly reactive crystal faces. In the later stage, the dissolution exhibited essentially the same behavior as non-activated ilmenite. (c) 2006 Elsevier Ltd. All rights reserved.