To investigate the effects of grinding media shapes on the grinding kinetics of ball mill cement clinker, the grinding effects with 4)20 mm balls and phi 20 x 20 mm cylinders on six different size fractions, i.e. -4.75+4.00 mm, -4.00+335 mm, -335+236 mm, -236+2.00 mm, -2.00+1.70 mm and -1.70+1.18 mm of cement clinkers, were studied in a laboratory scale ball mill. The specific rate of breakage and the primary breakage distribution function were compared for the balls and cylinders. Result shows that cement clinker obeys first-order grinding kinetics in the case of both balls and cylinders. The specific rate of breakage of cylinders is higher than that of balls. The primary breakage distribution parameters are dependent on the initial feed size. The phi value of cylinders is higher than that of balls. (C) 2012 Elsevier B.V. All rights reserved.