Moisture capacity is a new measure for representing the ability of iron ores to hold water, and was introduced, along with the equipment for measuring it, in previous studies. In practice, the time for the mixing and granulation of raw materials is limited. Therefore, the kinetics of water absorption into the mixture is of importance. The mathematical model, which refers to the capillary tubes, open pores, and closed pores was developed for explaining the water absorption rate curves. The calculations by the mathematical models were used to compare with the measurements. It was found that the kinetics of water absorption increases with the size of the capillary tube and the size of the closed pores, while the open pores have little effect on water absorption kinetics. The ores with greater particle size can absorb water more easily and faster than the ones with small particles because of the greater capillary tube formed. The ores with high pore volume slow the water absorption rate. Neither the capillary tube model nor the closed pore model can give the full and exact explanations of the measurement. Only the combination of the two models can give a very good simulation of the measurements. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.