Results of investigations of the effect of particle size composition of the raw material and the amount of wetting liquid supplied to the bed on the energy needed for growth and consolidation of granules during wet drum granulation process are presented in the paper. Energy consumption at subsequent stages of the granulation process was determined on the basis of the instantaneous values of torque recorded every 1 s on the granulator shaft. (C) 2004 Elsevier B.V. All rights reserved.