Cupric sulfide, CuS, was ground by a planetary ball mill under various experimental conditions, including variations in rotation speed and grinding time. The changes in crystal structure, lattice parameter, particle size, pore structure, and specific surface area in the ground powders were determined. With regard to the CuS ground at 700 rpm, the changes of the crystal structure were more remarkable than those of the CuS ground at 300 rpm. The crystallite size decreased (from 18.5 to 8.4 nm) and the lattice strain increased (from 1.60% to 3.09%) in the CuS ground at 700 rpm. Moreover, the lattice parameter a increased, while the lattice parameter c decreased. Grinding at 300 rpm is favorable for inducing changes of the physical properties, such as the growth of pore volume and specific surface area. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.