The Fe2O3 particles were reduced with CO in a fluidized bed and the sticking time as a process parameter was defined based on the pressure drop to describe the sticking. Influences of fluidized conditions (CO concentration, reduction potential, gas velocity and temperature) on the sticking time were compared. The order is temperature> CO concentration > reduction potential > gas velocity. On account of increasing iron-iron contact area when particles collided together, which resulted from increase of the metallization ratio and the specific surface area of particles, the sticking time decreased with increasing CO concentration and reduction potential. On the other hand, the sticking time increased with gas velocity for enhancing momentum of particles. Due to increase of the surface energy of precipitated iron, as a dominant source of driving force for sticking, the sticking time decreased with increasing temperature. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.