High-purity alumina powders with different particle morphology were prepared for the study of the evaluation of the activation energy of sintering. In this investigation, the evaluation of the activation energy is based on nonisothermal and isothermal sintering, in which the evaluated values were higher for the former than the latter. The abnormally higher value of the activation energy based on the nonisothermal sintering for the classified powder compact may be resulted from the low heating rate, which is attributed to the fact that the relative contribution of D-l and D-b to densification is different. Pore morphology also plays a role in evaluating the activation energy of sintering. (C) 2002 Elsevier Science B.V. All rights reserved.